1A* PWM/VFM Dual Step-down DC/DC Converter with Synchronous Rectifier

Transcription

1 RP55K1A 1A* PWM/VFM Dual Step-down DC/DC Converter with Synchronous Rectifier OUTLINE NO.EA RP55K1A is a CMOS-based 1A* dual step-down DC/DC converter with synchronous rectifier. Internally, each converter consists of oscillators, reference voltage units, error amplifiers, switching control circuits, soft-start circuit, latch type protection circuit, an under voltage lockout (UVLO) circuit, a thermal shutdown circuit and switching transistors. By adopting a synchronous rectifier with built-in switching transistors, a low ripple high efficiency synchronous rectifier step-down DC/DC converter can be easily configured with simply using two inductors, resistors and capacitors as the external components. RP55K1A is available in DFN(PLP) package which achieves high-density mounting on boards. Output voltage is adjustable with external divider resistors. Latch type protection circuit latches the built-in driver to the OFF state during high load or if the output is short-circuited for a specified time (protection delay time). The latch type protection circuit can be released by once setting the converter into the standby mode with the CE pin and then setting it back to the active mode, or, by turning the power off and back on. Setting the supply voltage lower than the UVLO detector threshold can also release the latch type protection circuit. Thermal shutdown circuit detects overheating of the converter and stops the converter operation to protect it from damage if the junction temperature exceeds the specified temperature. By inputting a signal to MODE pin, RP55K1A can choose PWM/VFM auto switching control or forced PWM control. In low output current, PWM/VFM auto switching control automatically switches from PWM mode to VFM mode in order to achieve high efficiency. Likewise, in low output current, forced PWM control switches at fixed frequency in order to reduce noise. When the both converters are in PWM mode, the converters operate with 18º turn-on phase shift of the switching transistors. FEATURES * This is an approximate value; output current depends on conditions and external components. Supply Current Typ. 45μA (VFM mode with no load/ 1 channel) Standby Current Max. 1μA Input Voltage Range 2.3V to 5.5V (V SET.8V) Range Adjustable from.6v (Recommended range is up to 3.3V) Feedback Voltage Accuracy ±9mV (VFB=.6V) Temperature Coefficient ±1ppm/ C Oscillator Frequency Typ. 2.25MHz Oscillator Maximum Duty Min. 1% Built-in Driver ON Resistance Typ. Pch..25Ω, Nch..21Ω (VIN=3.6V) UVLO Detector Threshold Typ. 2.V Soft Start Time Typ..2ms Lx Current Limit Circuit Typ. 17mA/ channel Latch Type Protection Circuit Typ. 1.5ms Package DFN(PLP)

2 RP55K1A APPLICATION Power source for portable communication equipment, camcorder, DSC, Notebook PC Power source for HDD, WLAN Power source for Li-ion battery-used equipment BLOCK DIAGRAM SLOPE CONPENSATION CURRENT FEEDBACK VIN CE1 CHIP ENABLE CURRENT PROTECTION LX1 VFB1 SWITCHING CONTROL SOFTSTART PWM / VFM CONTROL PGND1 VREF AGND MODE UVLO PROTECTION THERMAL PROTECTION CLK OSCILLATOR CLK 18 SLOPE CONPENSATION CURRENT FEEDBACK VIN CE2 CHIP ENABLE CURRENT PROTECTION LX2 VFB2 SWITCHING CONTROL SOFTSTART PWM / VFM CONTROL CLK 18 PGND2 VREF 2

3 RP55K1A SELECTION GUIDE Product Name Package Quantity per Reel Pb Free Halogen Free RP55K1A-TR DFN(PLP) ,pcs Yes Yes Output voltage is adjustable with external divider resistors. Recommended output voltage range is from.6v to 3.3V. PIN CONFIGURATIONS DFN(PLP) Top View Bottom View PIN DESCRIPTIONS RP55K1A: DFN(PLP) *1 Pin No. Symbol Description 1 VFB2 Channel 2 Feedback Pin 2 MODE 3 VIN Input Pin *2 4 VIN Input Pin *2 5 AGND Analog Ground Pin *3 6 VFB1 Channel 1 Feedback Pin Mode Control Pin ( H Forced PWM Control, L PWM/VFM Auto Switching Control) 7 CE1 Channel 1 Chip Enable Pin ( H active) 8 LX1 Channel 1 Lx Switching Pin 9 PGND1 Channel 1 Power Ground Pin *3 1 PGND2 Channel 2 Power Ground Pin *3 11 LX2 Channel 2 Lx Switching Pin 12 CE2 Channel 2 Chip Enable Pin ( H active) *1 The tab on the bottom of the package enhances thermal performance and is electrically connected to GND (substarate level). It is recommended that the tab be connected to the ground plane on the board. If not, the tab can be left open. *2 No.3 pin and No.4 pin must be wired to the V IN plane when mounting on boards. *3 No.5 pin, No.9 pin and No.1 pin must wired to the GND plane when mounting on boards. 3

4 RP55K1A ABSOLUTE MAXIMUM RATINGS (AGND=PGND1=PGND2=V) Symbol Item Rating Unit VIN VIN Input Pin Voltage -.3 to 6.5 V VLX1, VLX2 LX1, LX2 Pin Voltage -.3 to VIN +.3 V VCE1, VCE2 CE1, CE2 Pin Voltage -.3 to 6.5 V VMODE MODE Pin Voltage -.3 to 6.5 V VFB1, VFB2 VFB1, VFB2 Pin Voltage -.3 to 6.5 V ILX1, ILX2 LX1, LX2 Pin 1.7 A PD Standard Land Pattern *1 Power Dissipation *1 1 mw High Wattage Land Pattern *1 195 mw TTa Operating Temperature Range -4 to +85 C TTstg Storage Temperature Range -55 to +125 C * 1 For more information about Power Dissipation, Standard Land Pattern and High Wattage Land Pattern, please refer to PACKAGE INFORMATION. ABSOLUTE MAXIMUM RATINGS Electronic and mechanical stress momentarily exceeded absolute maximum ratings may cause the permanent damages and may degrade the lifetime and safety for both device and system using the device in the field. The functional operation at or over these absolute maximum ratings is not assured. RECOMMENDED OPERATING CONDITIONS (ELECTRICAL CHARACTERISTICS) All of electronic equipment should be designed that the mounted semiconductor devices operate within the recommended operating conditions. The semiconductor devices cannot operate normally over the recommended operating conditions, even if when they are used over such conditions by momentary electronic noise or surge. And the semiconductor devices may receive serious damage when they continue to operate over the recommended operating conditions. 4

5 RP55K1A ELECTRICAL CHARACTERISTICS Test Circuit is OPEN LOOP and Test Condition is AGND=PGND1=PGND2=V, unless otherwise noted. RP55K1A (Ta=25 C) Symbol Item Conditions Min. Typ. Max. Unit VIN Operating Input Voltage.8V V SET * V V SET <.8V VFB Feedback Voltage VIN=VCE1,2=3.6V V ΔVFB/ΔTTa Temperature Coefficient -4 C Ta 85 C ±1 ppm/ C fosc Oscillator Frequency VIN=VCE1,2=3.6V MHz *1 VIN=VCE1,2=5.5V, IDD1 Supply Current 1 VFB1,2=.45V, VMODE=V *1 VIN=VCE1,2=5.5V, IDD2 Supply Current 2 VFB1,2=.75V, VMODE=V *1 VIN=VCE1,2=5.5V, IDD3 Supply Current 3 VFB1,2=.75V, VMODE=5.5V V 8 11 μa 45 6 μa 8 11 μa Istandby Standby Current *1 VIN=5.5V, VCE1=VCE2=V 1 μa ICEH CE H Input Current *1 VIN=5.5V, VCE1,2=5.5V -1 1 μa ICEL CE L Input Current *1 VIN=5.5V, VCE1,2=V -1 1 μa IMODEH MODE H Input Current VIN=VMODE=5.5V -1 1 μa IMODEL MODE L Input Current VIN=5.5V, VMODE=V -1 1 μa IFBH VFB H Input Current *1 VIN=VFB1,2=5.5V, VCE1,2=V -1 1 μa IFBL VFB L Input Current *1 VIN=5.5V, VCE1,2=VFB1,2=V -1 1 μa ILXLEAKH LX Leakage Current H *1 VIN=VLX1,2=5.5V, VCE1,2=V -1 5 μa ILXLEAKL LX Leakage Current L *1 VIN=5.5V, VCE1,2=VLX1,2=V -5 1 μa VCEH CE H Input Voltage VIN=5.5V 1. V VCEL CE L Input Voltage VIN=2.3V.4 V VMODEH MODE H Input Voltage VIN=5.5V 1. V VMODEL MODE L Input Voltage VIN=2.3V.4 V RONP Pch Transistor ON Resistance VIN=3.6V, ILX1,2=-1mA.25 Ω RONN Nch Transistor ON Resistance VIN=3.6V, ILX1,2=-1mA.21 Ω Maxduty Oscillator Maximum Duty Cycle 1 % tstart Soft-start Time VIN=VCE1,2=3.6V 2 3 μs ILXLIM LX Limit Current VIN=VCE1,2=3.6V ma tprot Protection Delay Time VIN=VCE1,2=3.6V ms VUVLO1 UVLO Detector Threshold VIN=VCE1, V VUVLO2 UVLO Released Voltage VIN=VCE1, V TTSD Thermal Shutdown Temperature Junction Temperature 14 C TTSR Thermal Shutdown Released Temperature Junction Temperature 1 C 5

6 RP55K1A *1 For Standby Current, the sum of Channel 1 and Channel 2 is indicated. As for the following currents, either Channel 1 or Channel 2 is indicated. Supply Current 1 to Supply Current 3 CE H Input Current CE L Input Current VFB H Input Current VFB L Input Current LX Leakage Current H LX Leakage Current L *2 V SET = Setting 6

7 RP55K1A TYPICAL APPLICATION VIN 2.3V - 5.5V L1 2.2μH VOUT1 = 1.8V VIN LX1 R11 C11 2kΩ 22pF CE1 VFB1 R12 COUT1 1μF 1kΩ MODE PGND1 RP55K1A L2 2.2μH VOUT2 = 2.5V VIN LX2 R21 C21 317kΩ 22pF CIN 1μF CE2 VFB2 R22 COUT2 1μF 1kΩ AGND PGND2.8V V SET 3.3V Symbol Note: MODE= H Forced PWM Control MODE= L PWM/VFM Auto Switching Control Recommended Components CIN 1μF Ceramic Capacitor C168JBJ16M (TDK) COUT 1μF Ceramic Capacitor C168JBJ16M (TDK) L 2.2μH Inductor MIPSA252D2R2 (FDK).6V V SET <.8V Symbol Recommended Components CIN 1μF Ceramic Capacitor C168JBJ16M (TDK) COUT 1μF 2 Ceramic Capacitor C168JBJ16M (TDK) L 1.5μH Inductor MIPSA252D1R5 (FDK) 7

8 RP55K1A TECHNICAL NOTES When using RP55K1A, please consider the following points. AGND, PGND1 and PGND2 must be wired to the GND plane when mounting on boards. V IN pins must be wired to the V IN plane when mounting on boards. Ensure the V IN and GND lines are sufficiently robust. A large switching current flows through the GND line, the V DD line, the V OUT line, an inductor, and L X. If their impedance is too high, noise pickup or unstable operation may result. Set the external components as close as possible to the IC and minimize the wiring between the components and the IC. Especially, place the capacitor as close as possible to the V IN pin and GND. Separate the wiring between a resistor for setting output voltage (R11/ R21) and an inductor (L1/ L2) from the wiring between a capacitor (C11/ C21) and L1/ L2. Choose a low ESR ceramic capacitor. The ceramic capacitance of a capacitor (C IN ) connected between V IN and GND should be more than or equal to 1µF. The ceramic capacitance of a capacitor (C OUT ) connected between V OUT and GND should be 1µF to 2µF. Please be aware of the characteristics of bias dependence and temperature fluctuation of ceramic capacitor. The phase compensation of this IC is designed according to the above C OUT values and L values. For stable operation, a ceramic capacitance value and an inductance value have to be selected within these values. Choose an inductor that has small DC resistance, has enough allowable current and is hard to cause magnetic saturation. If the inductance value of an inductor is extremely small, the peak current of L X may increase along with the load current. As a result, over current protection circuit may start to operate when the peak current of L X reaches to L X limit current. Over current protection circuit and latch type protection circuit may be affected by self-heating or power dissipation environment. The output voltages (V OUT1, V OUT2 ) are adjustable by changing the values of R11, R12, R21, and R22 as follows. VOUT1 =.6 (R11 + R12) / R12 (Recommended range:.6v VOUT1 3.3V) VOUT2 =.6 (R21 + R22) / R22 (Recommended range:.6v VOUT2 3.3V) If R11, R12, R21, and R22 are too large, the impedances of V FB1 and V FB2 also become large, as a result, the IC could be easily affected by noise. For this reason, R12 and R22 should be 1kΩ or less. If the operation becomes unstable dues to the high impedances, the impedances should be decreased. C11 and C21 can be calculated by the following equations. Please use the value close to the calculation result. C11 = / R12 [F] (.6V VOUT1 3.3V) C21 = / R22 [F] (.6V VOUT2 3.3V) The recommended resistance values for R11, R12, R21, R22, C11, and C21 are as follows. VOUT1, VOUT2 [V] R11, R21 [kω] R12, R22 [kω] C11, C21 [pf] The performance of power source circuits using this IC largely depends on the peripheral circuits. When selecting the peripheral components, please consider the conditions of use. Do not allow each component, PCB pattern and the IC to exceed their respected rated values (voltage, current, and power) when designing the peripheral circuits. 8

9 RP55K1A OPERATION OF STEP-DOWN DC/DC CONVERTER AND OUTPUT CURRENT The step-down DC/DC converter charges energy in the inductor when L X Tr. turns ON, and discharges the energy from the inductor when L X Tr. turns OFF and controls with less energy loss, so that a lower output voltage (V OUT ) than the input voltage (V IN ) can be obtained. The operation of the step-down DC/DC converter is explained in the following diagrams. Diag. 1 Basic Circuit IL Diag. 2 Inductor (L) Current ILmax VIN Pch Tr L i1 VOUT ILmin i1 i2 topen GND Nch Tr i2 CL ton toff T=1/fosc Step 1: Pch Tr. is ON and current IL=i1 flows, and energy is charged into CL. At this moment, in proportion to the time while Pch Tr. is ON (t ON ), IL=i1 increases from IL=IL MIN =, and reaches IL MAX. Step 2: While Pch Tr. is OFF and synchronous rectifier Nch Tr. is ON, L tries to maintain IL= IL MAX, so IL=i2 flows into L. Step 3: IL=i2 decreases gradually and reaches IL=IL MIN = after the time while Pch Tr. is OFF and IL=IL MIN = (t OPEN ). Then, synchronous rectifier Nch Tr. turns OFF. Provided that in the continuous mode, next cycle starts before IL=IL MIN = because the time while Pch Tr. is OFF (t OFF ) is not enough. In this case, IL value increases from this IL MIN (>). In the case of PWM mode, V OUT is maintained by controlling t ON. During PWM mode, the oscillator frequency (f OSC ) is being maintained constant. As shown in Diag. 2, while the step-down operation is constant, the minimum inductor current (IL MIN ) and the maximum inductor current (IL MAX ) when Pch Tr. is ON would be same as the maximum and the minimum inductor currents when Pch Tr. is OFF. The current differential between IL MAX and IL MIN is described as ΔI. ΔI = IL MAX IL MIN = V OUT t OPEN / L = (V IN V OUT ) t ON / L Equation 1 However, T = 1 / f OSC = t ON + t OFF duty(%)= t ON / T 1 = t ON f OSC 1 t OPEN t OFF In Equation 1, V OUT t OPEN / L show the amount of current change at "ON". Also, (V IN V OUT ) t ON / L shows the amount of current change at "OFF". 9

10 RP55K1A Discontinuous Mode and Continuous Mode As illustrated in Diag 3., when the output current (I OUTT) is relatively small, t < t. In this case, the energy charged into the inductor during t will be completely discharged during t, as a result, IL =. This is called discontinuous mode. When I OUT is gradually increased, eventually t OPEN =t OFF and when I OUT is increased further, eventually IL MIN >. This is called continuous mode. OPEN ON OFF MIN OFF Diag 3. Discontinuous Mode Diag 4. Continuous Mode IL IL ILmax ILmax ILmin ILmin topen t Iconst t ton toff ton toff T=1/fosc T=1/fosc In the continuous mode, the solution of Equation 1 is t ONC. tonc = T V OUT / V IN Equation 2 When t ON <t ONC, it is discontinuous mode, and when t ON =t ONC, it is continuous mode. 1

11 RP55K1A Forced PWM Mode and VFM Mode By setting the MODE pin to H, the IC switches the frequency at the fixed rate to reduce noise even when the output load is light. Therefore, when I OUT is IL/2 or less, IL MIN becomes less than. That is, the accumulated electricity in CL is discharged through the IC side while IL is increasing from IL MIN to during ton time, and also while IL is decreasing from to IL MIN during t OFF time. Forced PWM Mode IL ILmax ΔIL IOUT ILmin t ton toff T=1/fosc By setting the MODE pin to L, in low output current, the IC automatically switches into VFM mode in order to achieve high efficiency. In VFM mode, ton is forced to end when the inductor current reaches the pre-set IL MAX. With RP55K, IL MAX in the VFM mode is typically set to 28mA. When t ON reaches 1.5 times of T=1/f OSC, t will be forced to end even if the inductor current is not reached IL MAX. ON VFM Mode IL ILmax ILmin t ton toff 11

12 RP55K1A and Selection of External Components The following equations explain the relationship between output current and peripheral components used in the diagram in TYPICAL APPLICATIONS. Ripple Current P-P value is described as IRP, ON resistance of Pch Tr. is described as RONP, ON resistance of Nch Tr. is described as RONN, and DC resistor of the inductor is described as RL. First, when Pch Tr. is ON, the following equation is satisfied. VIN = VOUT + (RONP + RL) IOUT + L IRP / ton Equation 3 Second, when Pch Tr. is "OFF" (Nch Tr. is "ON"), the following equation is satisfied. L IRP / toff = RONN IOUT + VOUT + RL IOUT Equation 4 Put Equation 4 into Equation 3 to solve ON duty of Pch Tr. (DON = ton / (toff + ton)): DON = (VOUT + RONN IOUT + RL IOUT)/(VIN + RONN IOUT RONP IOUT) Equation 5 Ripple Current is described as follows: IRP = (VIN VOUT RONP IOUT RL IOUT) DON / fosc / L Equation 6 Peak current that flows through L, and L X Tr. is described as follows: ILXmax = IOUT + IRP / 2 Equation 7 Please consider IL XMAX when setting conditions of input and output, as well as selecting the external components. The above calculation formulas are based on the ideal operation of the ICs in continuous mode. 12

13 RP55K1A TIMING CHART (1) Soft Start Time Starting-up with CE Pin The IC starts to operate when the CE pin voltage (V CE ) exceed the threshold voltage. The threshold voltage is preset between CE H input voltage (V CEH ) and CE L input voltage (V CEL ). After the start-up of the IC, soft-start circuit starts to operate. Then, after a certain period of time, the reference voltage (V REF ) in the IC gradually increases up to the specified value. CE Pin Input Voltage (VCE) IC Internal Voltage Reference (VREF) Lx Voltage (VLX) (VOUT) VCEH Threshold Level VCEL Soft-start Circuit operating Soft-start Time PWM mode operating during the Soft-start Time Depending on Power supply, Load Current, External Components Soft-start time starts when soft-start circuit activates, and ends when the reference voltage reaches the specified voltage. Soft start time is not always equal to the turn-on speed of the step-down DC/DC converter. Please note that the turn-on speed could be affected by the power supply capacity, the output current, the inductance value and the C OUT value. Starting-up with Power Supply After the power-on, the IC starts to operate when V IN exceed the UVLO released voltage (V UVLO2 ). Soft-start circuit starts to operate and then after a certain period of time, V REF in the IC gradually increases up to the specified value. Soft-start time starts when soft-start circuit activates, and ends when V REF reaches the specified voltage. V SET Input Voltage (VIN) IC Internal Voltage Reference (VREF) VUVLO2 VUVLO1 Soft-start Time Lx Voltage (VLX) PWM mode operating during the Soft-start Time (VOUT) V SET Depending on Power supply, Load Current, External Components Soft-start time starts when soft-start circuit activates, and ends when the reference voltage reaches the specified voltage. Please note that the turn-on speed of V OUT could be affected by the power supply capacity, the output current, the inductance value, the C OUT value and the turn-on speed of V IN determined by C IN. 13

14 RP55K1A (2) Under Voltage Lockout (UVLO) Circuit If V IN becomes lower than the setting voltage (V SET ), the step-down DC/DC converter stops the switching operation and ON duty becomes 1%, and then V OUT gradually drops according to V IN. If the V IN drops more and becomes lower than the UVLO detector threshold (V UVLO1 ), the UVLO circuit (UVLO) starts to operate, V REF stops, and Pch and Nch built-in switch transistors turn OFF. As a result, V OUT drops according to the C OUT capacitance value and the load. To restart the operation, V IN needs to be higher than V UVLO2. The timing chart below shows the voltage shifts of V REF, V LX and V OUT when V IN value is varied. Input Voltage (VIN) IC Internal Voltage Reference (VREF) V SET VUVLO2 VUVLO1 Soft-start Time Lx Voltage (VLX) (VOUT) V SET Depending on Power supply, Load Current, External Components Falling edge (operating) and rising edge (releasing) waveforms of V OUT could be affected by the initial voltage of C OUT and the output current of V OUT. 14

15 RP55K1A (3) Over Current Protection Circuit, Latch Type Protection Circuit Over current protection circuit supervises the inductor peak current (the peak current flowing through Pch Tr.) in each switching cycle, and if the current exceeds the L X current limit (I LXLIM ), it turns off Pch Tr. I LXLIM of the RP55K1A is set to Typ.17mA. Latch type protection circuit latches the built-in driver to the OFF state and stops the operation of the step-down DC/DC converter if the over current status continues or V OUT continues being the half of the setting voltage for equal or longer than protection delay time (tprot). Note: ILXLIM and tprot could be easily affected by self-heating or ambient environment. If the VIN drops dramatically or becomes unstable due to short-circuit, protection operation and tprot could be affected. Protection Delay Time (tprot) Lx Current Lx Current Limit (ILXLIM) Pch Tr. Current Lx Voltage (VLX) To release the latch type protection circuit, restart the IC by inputting "L" signal to CE pin, or restart the IC with power-on or make the supply voltage lower than VUVLO1. The timing chart below shows the voltage shifts of V LX and V OUT when the IC status is changed by the following orders: V IN and V CE rising stable operation high load CE reset stable operation high load V IN falling V IN recovering (UVLO reset) stable operation. (1)(2) If the large current flows through the circuit or the IC goes into low V OUT condition due to short-circuit or other reasons, the latch type protection circuit latches the built-in driver to OFF state after tprot. Then, VLX becomes "L" and V OUT turns OFF. (3) The latch type protection circuit is released by CE reset, which puts the IC into "L" once with the CE pin and back into "H". (4) The latch type protection circuit is released by UVLO reset, which makes V IN lower than VUVLO1. Input Voltage (VIN) V SET UVLO Released Voltage (VUVLO2) UVLO Detector Threshold (VUVLO1) (1) (3) (2) (4) CE Pin Input Voltage (VCE) V SET Threshold Level Protection Delay Time CE Reset UVLO Reset Protection Delay Time Lx Voltage (VLX) V SET (V OUT ) V SET Latch-type Protection Stable Operation Stable Operation Latch-type Protection Stable Operation Soft-start Time Soft-start Time Soft-start Time 15

16 RP55K1A CHARACTERISTICS 1) vs. RP55K1A VOUT=.6V RP55K1A VOUT=.6V V OUT Vin=3.6V.585 Vin=4.5V V OUT Vin=3.6V Vin=4.5V I OUT I OUT RP55K1A VOUT=.8V RP55K1A VOUT=.8V V OUT Vin=3.6V Vin=5.V V OUT Vin=3.6V Vin=5.V I OUT I OUT RP55K1A VOUT=1.2V RP55K1A VOUT=1.2V V OUT Vin=3.6V Vin=5.V I OUT V OUT Vin=3.6V Vin=5.V I OUT 16

17 RP55K1A RP55K1A VOUT=1.8V RP55K1A VOUT=1.8V V OUT Vin=3.6V Vin=5.V I OUT V OUT Vin=3.6V Vin=5.V I OUT RP55K1A VOUT=3.3V RP55K1A VOUT=3.3V V OUT Vin=4.3V Vin=5.V I OUT V OUT Vin=4.3V Vin=5.V I OUT 2) vs. Input Voltage RP55K1A VOUT=.8V RP55K1A VOUT=1.2V V OUT Iout=1mA Iout=1mA V OUT Iout=1mA Iout=1mA.785 Iout=8mA Iout=8mA Input Voltage VIN Input Voltage VIN 17

18 RP55K1A RP55K1A VOUT=1.8V RP55K1A VOUT=3.3V V OUT Iout=1mA Iout=1mA Iout=8mA V OUT Iout=1mA Iout=1mA Iout=8mA Input Voltage VIN Input Voltage VIN 3) Feedback Voltage vs. Ambient Temperature.69 FeedBack Voltage V FB VIN=3.6V Temperature Ta( ) 4) Efficiency vs. RP55K1A VOUT=.6V Efficiency (%) 1 9 VIN=4.5V, VMODE=V 8 VIN=3.6V, VMODE=V VIN=VMODE=4.5V VIN=VMODE=3.6V I OUT Efficiency (%) RP55K1A VOUT=.8V 1 9 VIN=5.V, VMODE=V 8 VIN=3.6V, VMODE=V VIN=VMODE=5.V VIN=VMODE=3.6V I OUT 18

19 RP55K1A Efficiency (%) RP55K1A VOUT=1.2V 1 VIN=5.V, VMODE=V 9 8 VIN=3.6V, VMODE=V VIN=VMODE=5.V VIN=VMODE=3.6V I OUT Efficiency (%) RP55K1A VOUT=1.8V VIN=5.V, VMODE=V VIN=3.6V, VMODE=V I OUT VIN=VMODE=5.V VIN=VMODE=3.6V RP55K1A VOUT=3.3V 1 Efficiency (%) VIN=4.3V, VMODE=V VIN=5.V, VMODE=V I OUT VIN=VMODE=5.V VIN=VMODE=4.3V 19

20 RP55K1A 5) Supply Current vs. Ambient Temperature 6) Supply Current vs. Input Voltage RP55K1A VOUT=1.8V(VIN=5.5V) RP55K1A VOUT=1.8V Supply Current (ua) Supply Current (ua) Closed Loop Open Loop Temperature Ta ( C) 35 3 Closed Loop Open Loop Input Voltage VIN 7) Waveform RP55K1A VOUT=.6V(VIN=3.6V) Output Ripple Voltage(AC) Vripple I OUT =1mA IL Inductor Current IL Output Ripple Voltage(AC) Vripple RP55K1A VOUT=.6V(VIN=3.6V) I OUT =1mA IL Inductor Current IL 2

21 RP55K1A RP55K1A VOUT=.8V(VIN=3.6V) RP55K1A VOUT=.8V(VIN=3.6V) I OUT =1mA 4 I OUT =1mA Output Ripple Voltage(AC) Vripple IL 1-1 Inductor Current IL Output Ripple Voltage(AC) Vripple IL 1-1 Inductor Current IL RP55K1A VOUT=1.2V(VIN=3.6V) RP55K1A VOUT=1.2V(VIN=3.6V) I OUT =1mA 4 I OUT =1mA Output Ripple Voltage(AC) Vripple IL 1-1 Inductor Current IL Output Ripple Voltage(AC) Vripple IL 1-1 Inductor Current IL 21

22 RP55K1A RP55K1A VOUT=1.8V(VIN=3.6V) I OUT =1mA 4 3 RP55K1A VOUT=1.8V(VIN=3.6V) I OUT =1mA Output Ripple Voltage(AC) Vripple IL 1-1 Inductor Current IL Output Ripple Voltage(AC) Vripple IL 1-1 Inductor Current IL RP55K1A VOUT=3.3V(VIN=4.3V) RP55K1A VOUT=3.3V(VIN=4.3V) I OUT =1mA 4 I OUT =1mA Output Ripple Voltage(AC) Vripple IL 1-1 Inductor Current IL Output Ripple Voltage(AC) Vripple IL 1-1 Inductor Current IL 22

23 RP55K1A 8) Oscillator Frequency vs. Ambient Temperature 9) Oscillator Frequency vs. Input Voltage Frequency fosc (MHz) VIN=3.6V Temperature Ta( C) Frequency fosc (MHz) C 25 C 85 C Input Voltage VIN 1) Soft-start Time vs. Ambient Temperature Soft Start Time tstart (μs) Temperature Ta( ) 11) UVLO Detector/ Released Threshold vs. Ambient Temperature UVLO Voltage V UVLO1 UVLO Detector Threshold Temperature Ta( ) UVLO Voltage V UVLO2 UVLO Released Threshold Temperature Ta( ) 23

24 RP55K1A 12) CE Input Voltage vs. Ambient Temperature CE H Input Voltage (VIN=5.5V) CE L Input Voltage (VIN=2.3V) CE Input Voltage V CEH CE Input Voltage V CEL Temperature Ta( ) Temperature Ta( ) 13) Lx Limit Current vs. Ambient Temperature LX Limit Current I LXLIM Temperature Ta( ) 14) Nch Transistor ON Resistance vs. 15) Pch Transistor ON Resistance vs. Ambient Temperature Ambient Temperature.4.4 Nch Tr. ONResistance R ON (Ω) Pch Tr. ONResistance R ON (Ω) Temperature Ta( ) Temperature Ta( ) 24

25 RP55K1A 16) Load Transient Response RP55K1A (VIN=3.6V, VOUT=.6V) 4 RP55K1A (VIN=3.6V, VOUT=.6V) 4 1mA-->3mA 2 3mA-->1mA 2 V OUT I OUT V OUT I OUT RP55K1A (VIN=3.6V, VOUT=.6V) RP55K1A (VIN=3.6V, VOUT=.6V) 4 4 1mA-->3mA 2 3mA-->1mA 2 V OUT I OUT V OUT I OUT RP55K1A (VIN=3.6V, VOUT=.6V) RP55K1A (VIN=3.6V, VOUT=.6V) 1 V OUT mA-->8mA I OUT V OUT mA-->3mA I OUT

26 RP55K1A RP55K1A (VIN=3.6V, VOUT=.8V) 4 RP55K1A (VIN=3.6V, VOUT=.8V) 4 1mA-->3mA 2 3mA-->1mA 2 V OUT I OUT V OUT I OUT RP55K1A (VIN=3.6V, VOUT=.8V) RP55K1A (VIN=3.6V, VOUT=.8V) 4 4 1mA-->3mA 2 3mA-->1mA 2 V OUT I OUT V OUT I OUT RP55K1A (VIN=3.6V, VOUT=.8V) RP55K1A (VIN=3.6V, VOUT=.8V) 1 V OUT mA-->8mA I OUT V OUT mA-->3mA I OUT

27 RP55K1A RP55K1A (VIN=3.6V, VOUT=1.2V) 4 RP55K1A (VIN=3.6V, VOUT=1.2V) 4 1mA-->3mA 2 3mA-->1mA 2 V OUT I OUT V OUT I OUT RP55K1A (VIN=3.6V, VOUT=1.2V) RP55K1A (VIN=3.6V, VOUT=1.2V) 4 4 1mA-->3mA 2 3mA-->1mA 2 V OUT I OUT V OUT I OUT RP55K1A (VIN=3.6V, VOUT=1.2V) RP55K1A (VIN=3.6V, VOUT=1.2V) 1 V OUT mA-->8mA I OUT V OUT mA-->3mA I OUT

28 RP55K1A RP55K1A (VIN=3.6V, VOUT=1.8V) 4 RP55K1A (VIN=3.6V, VOUT=1.8V) 4 V OUT mA-->3mA 2 IOUT V OUT mA-->1mA 2 IOUT RP55K1A (VIN=3.6V, VOUT=1.8V) RP55K1A (VIN=3.6V, VOUT=1.8V) 4 4 1mA-->3mA 2 3mA-->1mA 2 V OUT I OUT V OUT I OUT RP55K1A (VIN=3.6V, VOUT=1.8V) RP55K1A (VIN=3.6V, VOUT=1.8V) 1 V OUT mA-->8mA I OUT V OUT mA-->3mA I OUT

29 RP55K1A RP55K1A (VIN=5.V, VOUT=3.3V) 4 RP55K1A (VIN=5.V, VOUT=3.3V) 4 V OUT mA-->3mA 2 IOUT V OUT mA-->1mA 2 IOUT RP55K1A (VIN=5.V, VOUT=3.3V) RP55K1A (VIN=5.V, VOUT=3.3V) 4 4 1mA-->3mA 2 3mA-->1mA 2 V OUT I OUT V OUT I OUT RP55K1A (VIN=5.V, VOUT=3.3V) RP55K1A (VIN=5.V, VOUT=3.3V) 1 V OUT mA-->8mA I OUT V OUT mA-->3mA I OUT

30 RP55K1A 17) Mode Switching Waveform RP55K1A (VIN=3.6V, VOUT=1.2V, IOUT=1mA) MODE= L --> MODE= H 6 4 RP55K1A (VIN=3.6V, VOUT=1.2V, IOUT=1mA) MODE= H --> MODE= L 6 4 V OUT Mode Input Voltage 2 Mode Input Voltage V MODE VOUT Mode Input Voltage 2 Mode Input Voltage V MODE RP55K1A (VIN=3.6V, VOUT=1.8V, IOUT=1mA) MODE= L --> MODE= H RP55K1A (VIN=3.6V, VOUT=1.8V, IOUT=1mA) MODE= H --> MODE= L 6 4 V OUT Mode Input Voltage 2 Mode Input Voltage V MODE V OUT Mode Input Voltage 2 Mode Input Voltage V MODE

31 Ricoh presented with the Japan Management Quality Award for Ricoh continually strives to promote customer satisfaction, and shares the achievements of its management quality improvement program with people and society. Ricoh awarded ISO 141 certification. The Ricoh Group was awarded ISO 141 certification, which is an international standard for environmental management systems, at both its domestic and overseas production facilities. Our current aim is to obtain ISO 141 certification for all of our business offices. Ricoh completed the organization of the Lead-free production for all of our products. After Apr. 1, 26, we will ship out the lead free products only. Thus, all products that will be shipped from now on comply with RoHS Directive.