S-8351/52 Series. Rev.1.0_10. Features. Packages. Applications SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR

Transcription

1 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Features The S-8351/8352 Series is a CMOS PFM-control step-up switching regulator that mainly consists of a reference source, an oscillator, and a comparator. The PFM controller allows the duty ratio to be automatically switched according to the load (light load: 5%, high output current: 75%), enabling products with a low ripple over a wide range, high efficiency, and high output current (product types A, B, and D). Products with a fixed duty ratio of 75% are also available (product type C). With the S-8351 Series, a step-up switching regulator can be configured by using an external coil, capacitor, and diode. The built-in MOS FET is turned off by a protection circuit when the at the CONT pin exceeds the limit to prevent it from being damaged. This feature, along with the mini package and low current consumption, makes the S-8351 Series ideal for applications such as the power supply unit of portable equipment. The S-8352 Series, which features an external transistor, is suitable for applications requiring a high output current. Low operation: Low input current: Startup at.9 V min. () guaranteed During maximum operation: 2 µa (V OUT = 3.3 V, typ.) During shutdown:.5 µa (max.) Duty ratio: 5/75%, built-in auto-switching-type PFM controller (product types A, B, D) 75%, built-in fixed-type PFM controller (product type C) External parts: Coil, capacitor, diode : Settable to between 2. to 6.5 V (product types A, B, C) or 1.5 to 6.5 V (product type D) in.1 V steps, accuracy of ±2.4% Shutdown function (product type A) V DD /V OUT separate type (product type D) External transistor type available (S-8352 Series) Packages SOT-23-3 (package drawing code: MP3-A) SOT-23-5 (package drawing code: MP5-A) SOT-89-3 (package drawing code: UP3-A) Applications Power supply for portable equipment such as digital cameras, electronic notebooks, and PDAs Power supply for audio equipment such as portable CD/MD players Constant power supply for cameras, video equipment, and communications equipment Power supply for microcomputers 1

2 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 Applications 1. Function List Product Name Control System (Duty Ratio (%)) Switching Frequency (khz) Shutdown Function V DD/V OUT Separate Type Power MOS FET Package Application S-8351AxxMC PFM (5/75) 1 Yes Built-in SOT-23-5 Application requiring shutdown function S-8351BxxMA PFM (5/75) 1 Built-in SOT-23-3 Application not requiring shutdown function S-8351CxxMA PFM (75) 1 Built-in SOT-23-3 Application not requiring shutdown function S-8351CxxUA PFM (75) 1 Built-in SOT-89-3 Application not requiring shutdown function Application in which output is S-8351DxxMC PFM (5/75) 1 Yes Built-in SOT-23-5 adjusted by external resistance S-8352AxxMC PFM (5/75) 1 Yes External SOT-23-5 Application requiring shutdown function S-8352BxxMA PFM (5/75) 1 External SOT-23-3 Application not requiring shutdown function S-8352CxxMA PFM (75) 1 External SOT-23-3 Application not requiring shutdown function S-8352CxxUA PFM (75) 1 External SOT-89-3 Application not requiring shutdown function S-8352DxxMC PFM (5/75) 1 Yes External SOT-23-5 Application in which output is adjusted by external resistance 2. Product Name S-835 X X XX XX XXX T2 IC direction in tape specification Product name Package name MA; SOT-23-3 (without shutdown function) MC; SOT-23-5 (with shutdown function or V DD /V OUT separate type) UA; SOT-89-3 (without shutdown function) 1 (15 for output value 1.5) Product type A ; With shutdown function B ; Automatic duty ratio switching type C ; Duty ratio fixed type (75%) D ; V DD /V OUT separate type Series name 1; Built-in power MOS FET 2; External power MOS FET 2

3 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR 3. Product Name List Voltage S-8351AxxMC S-8351BxxMA S-8351CxxMA S-8351DxxMC Series Series S-8351CxxUA Series Series 3. S-8351A3MC-J2P-T2 S-8351B3MA-J4P-T2 3.3 S-8351A33MC-J2S-T2 3.5 S-8351A35MC-J2U-T2 5. S-8351A5MC-J3J-T2 5.5 S-8351A55MC-J3O-T2 Voltage S-8352AxxMC S-8352BxxMA S-8352CxxMA S-8352DxxMC Series Series S-8352CxxUA Series Series 2. S-8352D2MC-K8F-T2 3. S-8352A3MC-K2P-T2 S-8352B3MA-K4P-T2 5. S-8352A5MC-K3J-T2 Remark Please consult our sales staff if you require a product with an output other than those specified above. 3

4 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 Block Diagrams (1) S-8351 Series A type (with shutdown function) (2) S-8352 Series A type (with shutdown function) CONT Protection circuit IC internal power supply VOUT V REF VOUT IC internal power supply V REF PFM controller EXT PFM controller VSS VSS ON/OFF ON/OFF (3) S-8351 Series B, C type (without shutdown function) (4) S-8352 Series B, C type (without shutdown function) CONT Protection circuit IC internal power supply VOUT V REF IC internal power supply VOUT V REF PFM controller EXT PFM controller VSS VSS (5) S-8351 Series D type (V DD/V OUT separate type) (6) S-8352 Series D type (V DD/V OUT separate type) CONT VDD VOUT VDD VOUT IC internal power supply Protection circuit V REF IC internal power supply V REF PFM controller EXT PFM controller VSS VSS Figure 1. Block Diagrams 4

5 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Pin Assignment Top View Top View Top View SOT-23-5 SOT-23-3 SOT-89-3 Figure 2. Pin Assignment A type (with shutdown function) B, C type (without shutdown function) PKG: SOT-23-5 PKG: SOT-23-3 Pin No. Pin Name Functions Pin No. Pin Name Functions Shutdown pin 1 VOUT pin and IC power supply pin 1 ON/OFF 2 VOUT H : Normal operation 2 VSS GND pin (step-up operating) L : Step-up stopped CONT *1 External inductor connection pin (entire circuit stopped) 3 (S-8351 Series) pin and IC power EXT *2 External transistor connection pin supply pin (S-8352 Series) 3 (N.C.) 4 VSS GND pin 5 CONT *1 EXT *2 External inductor connection pin (S-8351 Series) External transistor connection pin (S-8352 Series) D type (V DD /V OUT separate type) PKG: SOT-23-5 Pin No. Pin Name Functions 1 VOUT pin C type (without shutdown function) 2 VDD IC power supply pin PKG: SOT (N.C.) Pin No. Pin Name Functions 4 VSS GND pin 1 VSS GND pin CONT *1 External inductor connection pin 2 VOUT pin and IC power 5 (S-8351 Series) supply pin EXT *2 External transistor connection pin CONT *1 External inductor connection pin (S-8352 Series) 3 (S-8351 Series) EXT *2 External transistor connection pin (S-8352 Series) *1. Open-drain output *2. CMOS output 5

6 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 Absolute Maximum Ratings Table 1. Absolute Maximum Ratings (Unless otherwise specified, Ta = 25 C) Parameter Symbol Ratings Unit VOUT pin V OUT V SS.3 to V SS 12 ON/OFF pin (A type) V ON/OFF V SS.3 to V SS 12 VDD pin (D type) V DD V SS.3 to V SS 12 CONT pin V CONT V SS.3 to V SS 12 EXT pin V EXT D type V SS.3 to V DD.3 Other than above V SS.3 to V OUT.3 CONT pin current I CONT 3 EXT pin current I EXT ±5 SOT Power dissipation P D SOT mw SOT Operating temperature T opr 4 to 85 Storage temperature T stg 4 to 125 Caution Although the IC contains a static electricity protection circuit, static electricity or that exceeds the limit of the protection circuit should not be applied. V ma C 6

7 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Electrical Characteristics 1-1. S-8351 Series Table 2. Electrical Characteristics (Unless otherwise specified, Ta = 25 C) Parameter Symbol Conditions Min. Typ. Max. Unit Test Circuit V OUT V OUT(S) V OUT(S) V.976 OUT(S) 1.24 V 1 Input V IN 1 V 1 Operation start V ST1.9 V 1 No external parts, applied to VOUT Oscillation start V ST2 CONT pulled up to VOUT via 3 Ωresistor.8 V 2 S-8351x15 to Input current without load I IN I OUT = ma S-8351x3 to µa 1 S-8351x5 to S-8351x15 to S-8351x2 to Current consumption 1 I SS1 V OUT =.95 S-8351x3 to S-8351x4 to µa 2 S-8351x5 to S-8351x6 to S-8351x15 to S-8351x2 to Current consumption 2 I SS2 V OUT =.5 S-8351x3 to S-8351x4 to µa 2 S-8351x5 to 59 S-8351x6 to Current consumption during shutdown (A type) I SSS Shutdown pin = V.5 µa 2 S-8351x15 to S-8351x2 to S-8351x25 to Switching current I SW V CONT =.4 V S-8351x3 to ma 2 S-8351x4 to S-8351x5 to S-8351x6 to Switching transistor leakage No external parts, V I CONT = V OUT = 1 V SWQ current Shutdown pin = V.5 µa 2 CONT limit V CONTLMT Apply to CONT pin, confirm oscillation stop.9 V 2 Line regulation V OUT1 V IN = V OUT(S).4 to mv 1 Load regulation V OUT2 I OUT = 1 µa to V OUT(S)/ mv 1 temperature VOUT coefficient Ta VOUT Ta = 4 C to 85 C ±5 ppm/ C 1 Maximum oscillation V f OUT =.95, measure waveform at OSC frequency CONT pin khz 2 Duty ratio 1 Duty1 V OUT =.95, measure waveform at CONT pin % 2 Duty ratio 2 (A, B, D type) Duty2 Measure waveform at CONT pin with light load 5 % 1 V V OUT =.95, judge oscillation at SH.75 Shutdown pin input CONT pin (A type) V 2 V SL1 V OUT =.95, When V OUT 1.5 V.3 V SL2 judge stop at CONT pin When V OUT < 1.5 V.2 Shutdown pin input I SH Shutdown pin = 1 V.1.1 current (A type) I SL Shutdown pin = V.1.1 µa 2 Efficiency EFFI S-8351x3 86 S-8351x5 88 % 1 External parts Coil: CDRH6D28-11 (1 µh) from Sumida Corporation Diode: MA2Z748 (Schottky type) from Matsushita Electronic Components Co., Ltd. Capacitor: F93 (16 V, 47 µf tantalum type) from Nichicon Corporation) V IN = V OUT(S).6 applied, I OUT = V OUT(S) / 25 Ω Shutdown function built-in type (A type): ON/OFF pin is connected to V OUT V DD/V OUT separate type (D type): VDD pin is connected to VOUT pin Remarks 1. V OUT(S) specified above is the set output value, and V OUT is the typical value of the actual output. 2. V DD/V OUT separate type (D type) A step-up operation is performed from V DD =.8 V. However, 1.8 V V DD 1 V is recommended to stabilize the output and oscillation frequency. (V DD 1.8 V must be applied for products with a set value of less than 1.9 V.) 7

8 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._ S-8352 Series Table 3. Electrical Characteristics (Unless otherwise specified, Ta = 25 C) Parameter Symbol Conditions Min. Typ. Max. Unit Test Circuit V OUT V OUT(S) V OUT(S) V.976 OUT(S) 1.24 V 3 Input V IN 1 V 3 Operation start V ST1.9 V 3 Oscillation start V ST2 No external parts, applied to VOUT.8 V 4 S-8352x15 to S-8352x2 to Current consumption 1 I S-8352x3 to SS1 V OUT =.95 S-8352x4 to µa 4 S-8352x5 to S-8352x6 to S-8352x15 to S-8352x2 to Current consumption 2 I SS2 V OUT =.5 S-8352x3 to S-8352x4 to µa 4 S-8352x5 to 59 S-8352x6 to Current consumption during shutdown (A type) I SSS Shutdown pin = V.5 µa 4 S-8352x15 to S-8352x2 to S-8352x25 to I EXTH V EXT = V OUT.4 V S-8352x3 to ma 4 EXT pin output current S-8352x4 to S-8352x5 to S-8352x6 to S-8352x15 to S-8352x2 to S-8352x25 to I EXTL V EXT =.4 V S-8352x3 to ma 4 S-8352x4 to S-8352x5 to S-8352x6 to Line regulation V OUT1 V IN = V OUT(S).4 to mv 3 Load regulation V OUT2 I OUT = 1 µa to V OUT(S)/ mv 3 temperature coefficient Maximum oscillation frequency Duty ratio 1 VOUT Ta VOUT f OSC Duty1 Ta = 4 C to 85 C ±5 ppm/ C 3 V OUT =.95, measure waveform at EXT pin V OUT =.95, measure waveform at EXT pin khz % 4 Duty ratio 2 (A, B, D type) Duty2 Measure waveform at EXT pin with light load 5 % 3 Shutdown pin input V SH V OUT =.95, measure oscillation at EXT pin.75 (A type) V SL1 V OUT =.95, When V OUT 1.5 V.3 V 4 V SL2 judge stop at EXT pin When V OUT < 1.5 V.2 Power off pin input I SH Shutdown pin = 1 V.1.1 µa 4 current (A type) I SL Shutdown pin = V.1.1 Efficiency EFFI S-8352x3 83 S-8352x5 85 % 3 External parts Coil: CDRH6D28-11 (1 µh) from Sumida Corporation Diode: MA2Z748 (Schottky type) from Matsushita Electronic Components Co., Ltd. Capacitor: F93 (16 V, 47 µf tantalum type) from Nichicon Corporation Transistor: CPH321 from Sanyo Electric Co., Ltd. Base resistor (Rb): 1 kω Base capacitor (Cb): 22 pf (ceramic type) V IN = V OUT(S).6 applied, I OUT = V OUT(S) / 1 Ω Shutdown function built-in type (A type): ON/OFF pin is connected to V OUT V DD/V OUT separate type (D type): VDD pin is connected to VOUT pin Remarks 1. V OUT(S) specified above is the set output value, and V OUT is the typical value of the actual output. 2. V DD/V OUT separate type (D type) A step-up operation is performed from V DD =.8 V. However, 1.8 V V DD 1 V is recommended to stabilize the output and oscillation frequency. (V DD 1.8 V must be applied for products with a set value of less than 1.9 V.) 8

9 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Test Circuits Cb CONT VSS VOUT (VDD) (ON/OFF) V Rb EXT VOUT (VDD) VSS (ON/OFF) V 2. 3 Ω 4. CONT (ON/OFF) VSS VOUT (VDD) A Oscilloscope Oscilloscope (ON/OFF) EXT VSS VOUT (VDD) A Figure 3. Test Circuits 1, 2, 3, and 4 9

10 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 Operation 1. Step-up DC/DC Converter The is a DC/DC converter that uses a pulse frequency modulation method (PFM) and features low current consumption. This series is an especially efficient DC/DC converter at an output current of 1 µa or lower. In conventional fixed-duty PFM DC/DC converters, although a low duty ratio allows a lower ripple when the current load is light, the efficiency is decreased when the output load current is large. Conversely, a high duty ratio increases the output load current and efficiency, but increases the ripple when the output load current is low. In the A, B, and D types, the duty ratio is automatically switched 75% when the output load current is high to secure the load drive capability, and 5% when the output load current is low to control the load drive capability to decrease pulse skipping. This suppresses a drop in the ripple frequency, enabling control of the increase in the ripple. The C type adopts a 75% fixed-duty PFM method. The ripple increases more than that of the duty switching type with the load is low, but the efficiency is better. In the A, B, and D types, the duty ratio is not rapidly changed, but rather smoothly switched in the intermediate area between 5% and 75%. Therefore, fluctuation of the ripple caused by duty switching is minimized. Figures 4 and 5 show the ripple characteristics versus the output current. These figures show that the ripple decreases as the output load current (I OUT ) changes from large to small. The ripple becomes particularly small when I OUT is in the coil current discontinuous region of 2 ma or less. S-8351A3MC Vrp-p (mv) Ta = 25 C V IN = 2 V I OUT (ma) Figure 4. Ripple Voltage Characteristics vs. Current (S-8351A3MC) S-8351A5MC Vrp-p (mv) Ta = 25 C 4 V IN = 2 V 2 V IN = 3 V I OUT (ma) Figure 5. Ripple Voltage Characteristics vs. Current (S-8351A5MC) Shutdown pin: Stops or starts step-up operation. (Only for product type A) Setting the shutdown pin to the L level stops operation of all the internal circuits and reduces the current consumption significantly. DO NOT use the shutdown pin in a floating state because it has the structure shown in Figure 6 and is not pulled up or pulled down internally. DO NOT apply a of between.3 V and.75 V to the shutdown pin because applying such a increases the current consumption. If the shutdown pin is not used, connect it to the VOUT pin. The shutdown pin does not have hysteresis. 1

11 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR VOUT Shutdown Pin CR Oscillator Voltage H Operating Fixed L Stopped V IN * * Voltage obtained by subtracting the drop due to the DC resistance of the inductor and the diode forward from V IN. ON/OFF VSS Figure 6. Shutdown Pin Structure V IN L Di ON/OFF CONT VOUT C L OSC M1 Figure 7. Step-Up Switching Regulator Circuit for Basic Equation The following are the basic equations [(1) through (7)] of the step-up switching regulator (see Figure 7). Voltage at CONT pin at the moment M1 is turned ON (current (I L ) flowing through L is zero), V A : V A = V S... (1) (V S : Non-saturated of M1) The change in I L over time: di L dt V L = = L V IN V S L... (2) Integration of the above equation (I L ): I L = V IN V S L t... (3) I L flows while M1 is ON (t ON ). The time of t ON is determined by the oscillation frequency of OSC. The peak current (I PK ) after t ON : I PK = V IN V S L The energy stored in L is represented by 1/2 L (I PK ) 2. When M1 is turned OFF (t OFF ), the energy stored in L is emitted through a diode. Then, the reverse (V L ) is generated: t ON... (4) V L = (V OUT V D ) V IN... (5) (V D : Diode forward ) 11

12 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 The at CONT pin rises only by V OUT V D. The change in the current (I L ) flowing through the diode into V OUT during t OFF : di L dt V L = = L V OUT V D V IN L... (6) Integration of the above equation is as follows: I L = I PK VOUT VD VIN L t... (7) During t ON, the energy is stored in L and is not transmitted to V OUT. When receiving the output current (I OUT ) from V OUT, the energy of the capacitor (C L ) is consumed. As a result, the pin of C L is reduced, and goes to the lowest level after M1 is turned ON (t ON ). When M1 is turned OFF, the energy stored in L is transmitted through the diode to C L, and the of C L rises rapidly. V OUT is a time function, and therefore indicates the maximum value (ripple : V P P) when the current flowing through into V OUT and load current (I OUT ) match. Next, the ripple is determined as follows: I OUT vs. t 1 (time) from when M1 is turned OFF (after t ON ) to when V OUT reaches the maximum level: V OUT V D V IN I OUT = I PK t L 1... (8) t 1 = (I PK I OUT) L V OUT V D V IN... (9) When M1 is turned OFF (t OFF ), I L = (when the energy of the inductor is completely transmitted): Based on equation (7), VOUT VD VIN When substituting equation (1) for equation (9), L = toff IPK... (1) t 1 = t OFF I OUT I PK t OFF... (11) Electric charge Q 1 which is charged in C L during t 1 : t1 V OUT V D t1 V IN t1 Q 1 = ILdt = I PK dt tdt L V OUT V D V IN 1 2 = I PK t 1 t 1... (12) L 2 When substituting equation (12) for equation (9): Q1 = IPK 1 IPK IOUT (IPK IOUT) t1 = t (13) A rise in (V P P) due to Q 1: VP-P = Q1 = 1 IPK IOUT t1 C L C L (14) 12

13 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR When taking into consideration I OUT to be consumed during t 1 and the ESR (Equivalent Series Resistance) of C L, namely R ESR : VP-P = Q 1 = 1 I PK I OUT t I PK I OUT 1 RESR CL CL 2 2 I OUT t 1 CL... (15) When substituting equation (11) for equation (15): (I V P-P = PK I OUT) 2 t OFF IPK IOUT R ESR 2I PK CL 2... (16) Therefore to reduce the ripple, it is important that the capacitor connected to the output pin has a large capacity and a small ESR. 13

14 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 External Part Selection 1. Inductor To minimize the loss due to inductor DC resistance, select an inductor with the smallest possible DC resistance (less than 1 Ω). Set the inductance value to around 22 µh to 1 mh. To make the average value of the output (V OUT ) constant, it is necessary to supply the energy corresponding to the output current (I OUT ) from the inductor. The amount of charge required for I OUT is I OUT (t ON t OFF ). Because the inductor can supply energy only during t OFF, the charge is obtained by integrating equation (7) with t OFF, namely, I PK 2 t OFF Thus, I PK 2 t OFF = I OUT (t ON t OFF )....(17) t I PK = 2 ON t OFF I OUT... (18) t OFF When the oscillation duty ratio of OSC is 75%, I PK = 8 I OUT. Therefore, an I PK current which is eight times I OUT flows into transistor M1. The S-8351 Series includes a switching current controller which monitors the current flowing into the CONT pin by the (CONT control ) and controls the current. This controller prevents destruction of the IC due to excess current. If an inductor with a large L value is selected, both I PK and I OUT decrease. Since the energy stored in the inductor is equal to ½ L (I PK ) 2, the energy decreases because I PK decreases in steps of squares offsetting the increase of L. As a result, stepping up at a low becomes difficult and the minimum operating input becomes high. However, the DC resistance loss of L and the M1 transistor decreases by the amount I PK decreased, and the inductance efficiency improves. On the other hand, if an inductor with a smaller L value is selected, both I PK and I OUT increase. Accordingly, the minimum operating input becomes low but the inductance efficiency deteriorates. Caution An excessively large I PK may cause magnetic saturation for some core materials, leading to the destruction of the IC. Use a core with material that satisfies I sat > I PK (I sat : Level of current that causes magnetic saturation). 2. Diode Use an external diode that meets the following requirements: Low forward : V F <.3V High switching speed: 5 ns max. Reverse : V OUT V F or more Rated current: I PK or more 14

15 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR 3. Capacitors (C IN, C L ) A capacitor at the input side (C IN ) improves the efficiency by reducing the power impedance and stabilizing the input current. Select the C IN value according to the impedance of the power supply used. The capacitor value should be around 1 µf. A capacitor at the output side (C L ) is used for smoothing the ripple. Therefore, select a capacitor with a small ESR (Equivalent Series Resistance) and a large capacitance. The capacitor value should be 1 µf min. A tantalum electrolytic capacitor and an organic semiconductor capacitor are especially recommended because of their superior low-temperature and leakage current characteristics. 4. External transistor (S-8352 Series) For the S-8352 Series, connecting an external transistor increases the output current. A bipolar (NPN) transistor or an enhancement (Nch) MOS FET transistor can be used as the external transistor. 4.1 Bipolar transistor A circuit example using a bipolar transistor (NPN), the CPH321 (h FE = 2 to 56) from Sanyo, is shown in Figure 12 and 13. The h FE and R b values of the bipolar transistor determine the driving capacity to increase the output current using a bipolar transistor. A peripheral circuit example of the transistor is shown in Figure 8. Pch VOUT Cb 22 pf I PK Rb EXT 1 kω Nch S-8352 Figure 8. External Transistor Peripheral Circuit The recommended R b value is around 1 kω. Actually, determine the required base current Ib from the bipolar transistor h FE assuming I b = I PK /h FE, and select the smaller R b value: R b = V OUT.7 I b.4 IEXTH VDD.7.4 ( R b = ) IEXTH I b A small Rb value can increase the output current, but reduces the efficiency. Since a current may flow on the pulse and the may drop due to wiring resistance or other factors, a test should be performed to determine the optimum value. If the speed-up capacitor (C b ) is inserted in parallel with the R b resistor as shown in Figure 8, the switching loss is decreased and the efficiency is improved. Select the C b value according to: C b 1 2π Rb f OSC.7 However, the best C b value varies depending on the characteristics of the bipolar transistor to be used, so determine the optimum value via testing. 15

16 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 4.2 Enhancement MOS FET type V OUT Figure 9 is a circuit example using a MOS FET transistor (N-channel). An N-channel power MOS FET should be used for MOS FET. In particular, the EXT pin of the S-8352 can drive a MOS FET with a gate capacitance of around 1 pf. Because the gate and current of the external power MOS FET are supplied from the stepped-up output V OUT, the MOS FET is driven more effectively. EXT (ON/OFF) VSS VOUT Figure 9. Circuit Example Using MOS FET A large current may flow during startup, depending on the MOS FET selection. The S-8352 Series does not feature overcurrent protection for the external MOS FET, so perform sufficient evaluation using the devices to be actually used. Since the on-resistance of the MOS FET might affect the output current as well as the efficiency, the threshold should be low. When the output is as low as 2. V, like in the S-8352A2, the circuit operates only when the MOS FET has a threshold lower than 2. V. 5. V DD /V OUT separate type ( D type) The D type provides separate internal circuit power supply and output setting pins (VDD and VOUT, respectively), making it ideal for the following applications. <1> Changing the output value using an external resistor <2> Setting a high output value, such as 15 V In this case, observe the following points when using this product. i) A step-up operation is performed from V DD =.8 V. However, 1.8 V V DD 1 V is recommended to stabilize the output and oscillation frequency. (V DD 1.8 V must be applied for products with a set value of less than 1.9 V.) If VDD is within the above range, the VDD pin can be connected to either the input pin VIN or the output pin VOUT. ii) There is impedance between the VOUT pin and VSS pin in the IC, so select external resistors R a and R b so that there are no negative effects when setting the output. The internal resistance between the VOUT and VSS pins are as follows. <1> S-835XD MΩ to 1 MΩ <2> S-835XD2 MΩ to 12.3 MΩ <3> S-835XD5 3.8 MΩ to 1.4 MΩ iii) If unstable operation such as oscillation of the output occurs, add capacitor C c in parallel with the R a resistor. Determine the C c value using the following equation. Cc (F) = 1 2 π R a 2 khz 16

17 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Standard Circuits (1) S-8351 Series A, B, C type L CONT SD VOUT VIN Protection circuit VREF CIN PFM controller CL VSS (ON/OFF) Figure 1. Standard Circuit (1) (2) S-8351 Series D type VIN CIN L CONT SD Protection circuit IC internal power supply PFM controller VDD VREF VOUT C C R a R b CL VSS Figure 11. Standard Circuit (2) 17

18 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 (3) S-8352 Series A, B, C type SD VOUT VIN CIN 22 pf 1 kω EXT PFM controller VREF CL VSS (ON/OFF) Figure 12. Standard Circuit (3) (4) S-8352 Series D type SD VIN CIN 22 pf 1 kω EXT IC internal power supply PFM controller VDD VREF C c R a R b CL VSS Figure 13. Standard Circuit (4) Caution The above connection diagram and constants do not guarantee correct operation. Perform sufficient evaluation using the actual application to set the constants. 18

19 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Power Dissipation of Package 6 SOT-89-3 Power dissipation P D (mw) 4 2 SOT-23-5 SOT Ambient temperature Ta ( C) Figure 12. Power Dissipation of Package (Before Mounting) Cautions Mount the external capacitors, diode, and coil as close as possible to the IC. Ripple and spike noise occur in switching regulators. Because they largely depend on the coil and the capacitor used, check these parameters using the actually mounted model. Seiko Instruments shall not be responsible for any patent infringement by products including S-8351/8352 Series in connection with the method of using S-8351/8352 Series in such products, the specification of such products, or the country of destination thereof. Ensure that the dissipation of the switching transistor (especially at high temperatures) does not exceed the allowable power dissipation of the package. When the impedance of the power supply is high, the shutdown pin is switched from L to H, or VIN is connected to the power supply, note that the power supply drops temporarily because a rush current flows into the power supply. 19

20 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 Characteristics (All Data Indicates Typical Values) 1. Current consumption vs. Power supply Power supply input current no load I IN [µa] (Ta = 25 C) S-8351A3MC S-8351A5MC V IN [V] I SS1 vs. V OUT, Ta S-8351A (Ta = 25 C) 8 I SS1 [µa] I SS1 [µa] S-8351A S-8351A3MC S-8351A5MC I SS1 [µa] S-8352A I SS2 vs. V OUT, Ta V OUT [V] (Ta = 25 C) V OUT [V] (Ta = 25 C) I SS1 [µa] Ta [ C] S-8352A S-8352A3MC S-8352A5MC Ta [ C] 5 4 S-8351A3MC S-8351A5MC I SS2 [µa] 3 2 I SS2 [µa] V OUT [V] Ta [ C] 2

21 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR 2. Oscillation frequency, duty ratio vs. Temperature S-8351A3MC S-8351A5MC f OSC [khz] Duty1 [%] Ta [ C] S-8351A3MC S-8351A5MC Ta [ C] Duty2 [%] S-8351A3MC S-8351A5MC Ta [ C] 3. Switching current vs., temperature I SW vs. V OUT, Ta (Ta = 25 C) 3 I SW [ma] V OUT [V] I SW [ma] 4. EXT pin output current vs., temperature I EXTH vs. V OUT, Ta (Ta = 25 C) 35 I EXTH [ma] V OUT [V] I EXTH [ma] Ta [ C] S-8351A3MC S-8351A5MC Ta [ C] S-8352A3MC S-8352A5MC 21

22 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 I EXTL vs. V OUT, Ta I EXTL [ma] (Ta = 25 C) V OUT [V] I EXTL [ma] 4 S-8352A3MC 3 S-8352A5MC Ta [ C] 5. Operation start, retention vs. Temperature V ST1 vs. Ta V HLD vs. Ta V ST1 [V] Ta [ C] S-8351A3MC S-8351A5MC V HLD [V] Ta [ C] S-8351A3MC S-8351A5MC Reference Data (1) 1. Transient response characteristics The conditions for external parts are the same as those specified in the electrical characteristics. 1.1 Power-on (Ta = 25 C) S-8351A3MC Input (.5 V/div) V (.5 V/div) V IN = 1.8 V, R L = 25 Ω 1.8 V 3 V S-8351A5MC Input (1 V/div) V (1 V/div) V IN = 3 V, R L = 25 Ω 3 V 5 V V t (.2 ms/div) V t (.2 ms/div) S-8352A3MC Input (.5 V/div) V (.5 V/div) V IN = 1.8 V, R L = 25 Ω 1.8 V 3 V S-8352A5MC Input (1 V/div) V (1 V/div) V IN = 3 V, R L = 25 Ω 3 V 5 V 22 V t (.2 ms/div) V t (.2 ms/div)

23 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR 1.2 Power supply fluctuation (Ta = 25 C) S-8351A3MC Input V IN = V, R L = 25 Ω (.5 V/div) 1.2 V (.1 V/div) 1.8 V 3 V 1.8 V Input (.5 V/div) (.1 V/div) S-8351A3MC V IN = V, R L = 25 Ω 1.2 V 3 V Input (.5 V/div) 2 V t (.1 ms/div) S-8351A5MC V IN = 2 3 V, R L = 25 Ω 3 V 3 V Input (.5 V/div) t (.1 ms/div) S-8351A5MC V IN = 3 2 V, R L = 25 Ω 2 V (.1 V/div) 5 V (.1 V/div) 5 V t (.1 ms/div) t (.1 ms/div) Input (.5 V/div) 1.2 V (.1 V/div) S-8352A3MC V IN = V, R L = 25 Ω 1.8 V 3 V 1.8 V Input (.5 V/div) (.1 V/div) S-8352A3MC V IN = V, R L = 25 Ω 1.2 V 3 V Input (.5 V/div) 2 V (.1 V/div) t (.1 ms/div) S-8352A5MC V IN = 2 3 V, R L = 25 Ω t (.1 ms/div) 3 V 5 V 3 V Input (.5 V/div) (.1 V/div) t (.1 ms/div) S-8352A5MC V IN = 3 2 V, R L = 25 Ω t (.1 ms/div) 2 V 5 V 23

24 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 1.3 Load current fluctuation (Ta = 25 C) S-8351A3MC V IN = 1.8 V, I OUT = 1 µa 12 ma S-8351A3MC V IN = 1.8 V, I OUT = 12 ma 1 µa current I OUT = 12 ma current I OUT = 1 µa (.1 V/div) 3 V 3 V (.1 V/div) t (.1 ms/div) t (.1 ms/div) S-8351A5MC V IN = 3 V, I OUT = 1 µa 2 ma S-8351A5MC V IN = 3 V, I OUT = 2 ma 1 µa current I OUT = 2 ma current I OUT = 1 µa (.1 V/div) 5 V 5 V (.1 V/div) t (.1 ms/div) t (.1 ms/div) S-8352A3MC V IN = 1.8 V, I OUT = 1 µa 12 ma S-8352A3MC V IN = 1.8 V, I OUT = 12 ma 1 µa current I OUT = 12 ma current I OUT = 1 µa (.1 V/div) 3 V 3 V (.1 V/div) t (.1 ms/div) t (.1 ms/div) S-8352A5MC V IN = 3 V, I OUT = 1 µa 2 ma S-8352A5MC V IN = 3 V, I OUT = 2 ma 1 µa current I OUT = 2 ma current I OUT = 1 µa (.1 V/div) 5 V 5 V (.1 V/div) t (.1 ms/div) t (.1 ms/div) 24

25 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR 1.4 Shutdown pin response (Ta = 25 C) ON/OFF S-8351A3MC V IN = 1.8 V, R L = 25 Ω ON OFF ON/OFF S-8351A5MC OFF ON V IN = 3 V, R L = 25 Ω (.3 V/div) 3 V 3 V (.5 V/div) t (.1 ms/div) t (.1 ms/div) ON/OFF S-8352A3MC V IN = 1.8 V, R L = 25 Ω ON OFF ON/OFF S-8352A5MC OFF ON V IN = 3 V, R L = 25 Ω (.3 V/div) 5 V 5 V (.5 V/div) t (.1 ms/div) t (.1 ms/div) Reference Data (2) The following shows the step-up characteristics when the coils in the table below are used for reference. Table 4 Model Manufacturer L Value DC Resistance Current Rating CDRH6D28-22 Sumida Corporation 22 µh.128 Ω 12 ma CDRH6D28-47 Sumida Corporation 47 µh.238 Ω 8 ma CDRH6D28-11 Sumida Corporation 1 µh.535 Ω 54 ma CDRH Sumida Corporation 22 µh.4 Ω 8 ma CXLP12-47 Sumitomo Special Metals Co., Ltd 47 µh.95 Ω 45 ma CXLP12-11 Sumitomo Special Metals Co., Ltd 1 µh 2.5 Ω 2 ma 1. S-8351A3MC (built-in, V OUT = 3 V) 1-1 CDRH6D28-47 (47 µh), Ta = 25 C (a) Input vs. (input stepped up) V OUT [V] 3. I OUT =.1 ma I OUT = 1mA I OUT = 2 ma I OUT = 5 ma Input V IN [V] (b) Input vs. (input stepped down) V OUT [V] 3. I OUT =.1 ma I OUT = 1mA I OUT = 2 ma I OUT = 5 ma Input V IN [V] 25

26 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 (c) current vs. VOUT [V] 3. V IN = 1. V V IN = 1.8 V V IN = 2. V V IN = 2.5 V current I OUT [ma] 25 (d) Efficiency vs. current Efficiency η [%] V IN = 1. V V IN = 1.8 V V IN = 2. V V IN = 2.5 V current I OUT [ma] 1-2 CDRH6D28-11 (1 µh), Ta = 25 C (a) Input vs. (input stepped up) VOUT [V] 3. I OUT =.1 ma I OUT = 2 ma I OUT = 5 ma Input V IN [V] (b) Input vs. (input stepped down) VOUT [V] 3. I OUT =.1 ma I OUT = 2 ma I OUT = 5 ma Input V IN [V] (c) current vs. VOUT [V] 3. V IN = 1. V V IN = 1.8 V V IN = 2. V V IN = 2.5 V current I OUT [ma] 25 (d) Efficiency vs. current Efficiency η [%] V IN = 1. V V IN = 1.8 V V IN = 2. V V IN = 2.5 V current I OUT [ma] 1-3 CXLP12-11 (1 µh), Ta = 25 C (a) Input vs. (input stepped up) VOUT [V] 3. I OUT =.1 ma I OUT = 2 ma I OUT = 5 ma Input V IN [V] (b) Input vs. (input stepped down) VOUT [V] 3. I OUT =.1 ma I OUT = 2 ma I OUT = 5 ma Input V IN [V] 26

27 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR (c) current vs. VOUT [V] 3. V IN = 1. V V IN = 1.8 V V IN = 2. V V IN = 2.5 V current I OUT [ma] 25 (d) Efficiency vs. current Efficiency η [%] V IN = 1. V V IN = 1.8 V V IN = 2. V V IN = 2.5 V current I OUT [ma] 2. S-8351A5MC (built-in, V OUT = 5 V) 2-1 CDRH6D28-11 (1 µh), Ta = 25 C (a) Input vs. (input stepped up) VOUT [V] 5. 1 IOUT =.1 ma IOUT = 1 ma IOUT = 1 ma IOUT = 5 ma IOUT = 1 ma IOUT = 15 ma Input VIN [V] (b) Input vs. (input stepped down) VOUT [V] 5. IOUT =.1 ma IOUT = 1 ma IOUT = 1 ma IOUT = 5 ma IOUT = 1 ma IOUT = 15 ma Input VIN [V] (c) current vs. VOUT [V] currentiout [ma] 2-2 CDRH (22 µh), Ta = 25 C VIN = 1.5 V VIN = 2. V VIN = 3. V 25 (d) Efficiency vs. current Efficiencyη [%] VIN = 1. V VIN = 1.5 V VIN = 2. V VIN = 3. V VIN = 4. V currentiout [ma] (a) Input vs. (input stepped up) VOUT [V] 5. 1 IOUT =.1 ma IOUT = 1 ma IOUT = 1 ma IOUT = 5 ma IOUT = 1 ma IOUT = 15 ma Input VIN [V] (b) Input vs. (input stepped down) VOUT [V] 5. IOUT =.1 ma IOUT = 1 ma IOUT = 1 ma IOUT = 5 ma IOUT = 1 ma IOUT = 15 ma Input VIN [V] 27

28 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 (c) current vs. VOUT [V] 5. V IN = 2. V V IN = 3. V current I OUT [ma] 25 (d) Efficiency vs. current Efficiency η [%] V IN = 1. V V IN = 2. V V IN = 3. V V IN = 4. V current I OUT [ma] 2-3 CXLP12-47 (47 µh), Ta = 25 C (a) Input vs. (input stepped up) VOUT [V] 5. 1 I OUT =.1 ma I OUT = 5 ma I OUT = 15 ma Input V IN [V] (b) Input vs. (input stepped down) VOUT [V] 5. I OUT =.1 ma I OUT = 5 ma I OUT = 15 ma Input V IN [V] (c) current vs. VOUT [V] 5. V IN = 2. V V IN = 3. V current I OUT [ma] 25 (d) Efficiency vs. current Efficiency η [%] V IN = 1. V V IN = 2. V V IN = 3. V V IN = 4. V current I OUT [ma] 28

29 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR 3. S-8352A3MC (external, V OUT = 3 V) 3-1 CDRH6D28-22 (22 µh), Ta = 25 C (a) Input vs. (input stepped up) VOUT [V] 3. I OUT =.1 ma I OUT = 5 ma I OUT = 15 ma Input V IN [V] (b) Input vs. (input stepped down) VOUT [V] 3. I OUT =.1 ma I OUT = 5 ma I OUT = 15 ma Input V IN [V] (c) current vs. VOUT [V] 3. 5 V IN = 1.8 V V IN = 2. V V IN = 2.5 V current I OUT [ma] 3 35 (d) Efficiency vs. current Efficiency η [%] V IN = 1.8 V V IN = 2. V V IN = 2.5 V current I OUT [ma] 3-2 CDRH6D28-11 (1 µh), Ta = 25 C (a) Input vs. (input stepped up) VOUT [V] 3. I OUT =.1 ma I OUT = 5 ma I OUT = 15 ma Input V IN [V] (b) Input vs. (input stepped down) VOUT [V] 3. I OUT =.1 ma I OUT = 5 ma I OUT = 15 ma Input V IN [V] (c) current vs. VOUT [V] 3. V IN = 1.8 V V IN = 2. V V IN = 2.5 V current I OUT [ma] (d) Efficiency vs. current Efficiency η [%] V IN = 1.8 V V IN = 2. V V IN = 2.5 V current I OUT [ma] 29

30 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR Rev.1._1 3-3 CXLP12-47 (47 µh), Ta = 25 C (a) Input vs. (input stepped up) VOUT [V] Input V IN [V] (c) current vs. VOUT [V] 4. S-8352A5MC (external, V OUT = 5 V) 4-1 CDRH6D28-22 (22 µh), Ta = 25 C I OUT =.1 ma I OUT = 5 ma I OUT = 15 ma current I OUT [ma] (a) Input vs. (input stepped up) VOUT [V] 5. 1 V IN = 1.8 V V IN = 2. V V IN = 2.5 V I OUT =.1 ma I OUT = 5 ma I OUT = 15 ma Input V IN [V] (b) Input vs. (input stepped down) VOUT [V] 3. (d) Efficiency vs. current Efficiency η [%] I OUT =.1 ma I OUT = 5 ma I OUT = 15 ma Input V IN [V] V IN = 1.8 V V IN = 2. V V IN = 2.5 V current I OUT [ma] (b) Input vs. (input stepped down) VOUT [V] 5. I OUT =.1 ma I OUT = 5 ma I OUT = 15 ma Input V IN [V] (c) current vs. VOUT [V] 5. 5 V IN = 2. V V IN = 3. V V IN = 4. V current I OUT [ma] (d) Efficiency vs. current Efficiency η [%] V IN = 2. V V IN = 3. V V IN = 4. V current I OUT [ma] 3

31 Rev.1._1 SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR 4-2 CDRH6D28-11 (1 µh), Ta = 25 C (a) Input vs. (input stepped up) VOUT [V] 5. 1 I OUT =.1 ma I OUT = 5 ma I OUT = 15 ma Input V IN [V] (b) Input vs. (input stepped down) VOUT [V] 5. I OUT =.1 ma I OUT = 5 ma I OUT = 15 ma Input V IN [V] (c) current vs. VOUT [V] 5. V IN = 2. V V IN = 3. V V IN = 4. V current I OUT [ma] (d) Efficiency vs. current Efficiency η [%] V IN = 2. V V IN = 3. V V IN = 4. V current I OUT [ma] 4-3 CXLP12-11 (1 µh), Ta = 25 C (a) Input vs. (input stepped up) VOUT [V] 5. 1 I OUT =.1 ma I OUT = 5 ma (b) Input vs. (input stepped down) VOUT [V] 5. I OUT =.1 ma I OUT = 5 ma Input V IN [V] Input V IN [V] (c) current vs. VOUT [V] 5. V IN = 2. V V IN = 3. V V IN = 4. V current I OUT [ma] (d) Efficiency vs. current Efficiency η [%] V IN = 3. V V IN = 4. V current I OUT [ma] 31

32

33

34

35 The information described herein is subject to change without notice. is not responsible for any problems caused by circuits or diagrams described herein whose related industrial properties, patents, or other rights belong to third parties. The application circuit examples explain typical applications of the products, and do not guarantee the success of any specific mass-production design. When the products described herein are regulated products subject to the Wassenaar Arrangement or other agreements, they may not be exported without authorization from the appropriate governmental authority. Use of the information described herein for other purposes and/or reproduction or copying without the express permission of is strictly prohibited. The products described herein cannot be used as part of any device or equipment affecting the human body, such as exercise equipment, medical equipment, security systems, gas equipment, or any apparatus installed in airplanes and other vehicles, without prior written permission of Although exerts the greatest possible effort to ensure high quality and reliability, the failure or malfunction of semiconductor products may occur. The user of these products should therefore give thorough consideration to safety design, including redundancy, fire-prevention measures, and malfunction prevention, to prevent any accidents, fires, or community damage that may ensue.