AIC1848 C+ 6 VIN 5 C FLY. Regulated 5V Output from 2.7V to 4.5V Input WLED series number: NSPW310BS, V F =3.6V, I F =20mA

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1 FEATURES Regulated ±% Output Voltage Output Current: 00mA at V IN =.V Input Range:.7V to.5v No Inductors Required Very Low Shutdown Current: <µa.8mhz Switching Frequency Short-Circuit and Over Temperature Protection Low Profile Package: SOT--6 APPLICATIONS White LEDs Backlighting SIM Interface Supplies for Cellular Telephones Li-Ion Battery Backup Supplies Local V to 5V Conversion Smart Card Readers PCMCIA Local 5V Supplies TYPICAL APPLICATION CIRCUIT AIC88 Regulated 5V Charge Pump In SOT- DESCRIPTION The AIC88 charge pump is a micropower charge pump DC/DC converter that produces a regulated output voltage from.7v to.5v input voltage. Low external-part count (one 0.µF flying capacitor and two small bypass capacitors) make the AIC88 ideal for small, battery-powered applications. The AIC88 operates as a constant frequency mode switched capacitor voltage doubler to produce a regulated output and features with thermal shutdown capability and short circuit protection. The AIC88 is available in a space-saving SOT--6 package. V OUT -Cell Li-ion Battery µf U C+ 6 5 µf R R R C- C FLY µf AIC88 Regulated 5V Output from.7v to.5v Input WLED series number: NSPW0BS, V F =.6V, I F =0mA V R = OUT I V F F, C FLY, : JMK07BJ05KA, TAIYO YUDEN Analog Integrations Corporation Si-Soft Research Center DS-88-P 0 A, No., Li-Hsin Rd. I, Science Park, Hsinchu 00, Taiwan, R.O.C. TEL: FAX:

2 AIC88 ORDERING INFORMATION AIC88-XXXX PACKING TYPE TR: TAPE & REEL BG: BAG PACKAGE TYPE G: SOT--6 PIN CONFIGURATION SOT--6 TOP VIEW C+ 6 5 C- (MARK SIDE) Example: AIC88CGTR in SOT--6 Package & Taping & Reel Packing Type AIC88PGTR C: COMMERCIAL P: LEAD FREE COMMERCIAL in SOT--6 Lead Free Package & Taping & Reel Packing Type SOT--6 Marking Part No. Marking Part No. Marking AIC88CG BP50 AIC88PG BP50P ABSOLUATE MAXIMUM RATINGS to to All Other Pins to Short-Circuit Duration 6V 6V 6V Continuous Operating Temperature Range -0 C to 85 C Maximum Operation Junction Temperature 5 C Storage Temperature Range -65 C to 50 C Lead Temperature (Sordering 0 Sec.) 60 C Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.

3 AIC88 TEST CIRCUIT Refer to Typical Application Circuit. ELECTRICAL CHARACTERISTICS (T A =5 C, C FLY =µf, =µf, =µf, unless otherwise specified.) (Note ) PARAMETER TEST CONDITIONS SYMBOL MIN. TYP. MAX. UNIT Input Voltage V IN.7.5 V Output Voltage Supply Current Shutdown Current.7V V IN <.5V, I OUT 0mA.V V IN.5V, I OUT 00mA.7V V IN 5.0V, I OUT =0, =V IN.7V V IN 5.0V, I OUT =0, =0V V OUT I CC 5 ma I µa Efficiency V IN =.7V, I OUT =0mA η 85 % Switching Frequency Oscillator Free Running f OSC.8 MHz Shutdown Input Threshold (High) Shutdown Input Threshold (Low) Shutdown Input Current (High) Shutdown Input Current (Low) V IH.5 V V IL 0. V =V IN I IH - µa = 0V I IL - µa Vout Turn On Time V IN =V, I OUT = ma t ON 50 µs V Output Short Circuit Current V IN =V, V OUT = 0V, = V IN I SC 00 ma Note : Specifications are production tested at T A =5 C. Specifications over the -0 C to 85 C operating temperature range are assured by design, characterization and correlation with Statistical Quality Controls (SQC).

4 AIC88 TYPICAL PERFORMANCE CHARACTERISTICS Output Voltage (V) T A = -0 C T A =5 C T A =85 C I OUT =0mA = =C FLY =µf Output Voltage (V) = =C FLY =µf T A =5 C V IN =V V IN =.7V V IN =.V Supply Voltage (V) Fig. Output Voltage vs Supply Voltage Load Current (ma) Fig. Output Voltage vs. Load Current.0.0 Supply Current (µα) = =C FLY =µf V =V IN T A =5 C T A =-0 C T A =85 C Oscillator Frequency (MHz) T A = -0 C T A =5 C T A =85 C Supply Voltage (V) Fig. No Load Supply Current vs. Supply Voltage Supply Voltage (V) Fig. Oscillator Frequency vs. Supply Voltage Supply Current (µα) T A =5 C T A =-0 C T A =85 C Output Current (µα) = =C FLY =µf T A =5 C V OUT =0V Supply Voltage (V) Fig. 5 V Threshold Voltage vs. Supply Voltage Supply Voltage (V) Fig. 6 Short Circuit Current vs. Supply Voltage.5

5 AIC88 TYPICAL PERFORMANCE CHARACTERISTICS Vin=.7 Vin=.0V Vin=.7V Vin=.0V Efficiency (%) Vin=.V Vin=.7V Vin=.V Efficiency (%) Vin=.V Vin=.7V Vin=.V = =uf C FLY =uf 0 = =uf C FLY =0.uF Load Current (ma) Fig.7 Efficiency vs. Load Current Load Current (ma) Fig.8 Efficiency vs. Load Current 0 80 Ripple Voltage (V) = =µf C FLY =0.µF V IN =.7V V IN =.0V V IN =.V V IN =.6V Ripple (mvp-p) V IN =V C FLY =0.µF =uf =.uf Iout (ma) Output Current (ma) Fig. 9 Output Ripple Voltage Fig. 0 Output Ripple 5

6 AIC88 BLOCK DIAGRAM µf C+ V IN COMP Control C FLY µf µf C- VREF PIN DESCRIPTIONS PIN : - PIN : - Regulated output voltage. For the best performance, V OUT should be bypassed with a µf (min) low ESR capacitor with the shortest distance in between. Ground. Should be tied to a ground plane for best performance. PIN : - Active low shutdown input. A low voltage on disables the AIC88. is not allowed to float. PIN : C- - Flying capacitor negative terminal. PIN 5: - Input supply voltage. V IN should be bypassed with a µf (min) low ESR capacitor. PIN 6: C+ - Flying capacitor positive terminal. 6

7 AIC88 APPLICATION INFORMATION Introduction AIC88 is a micropower charge pump DC/DC converter that produces a regulated 5V output with an input voltage range from.7v to.5v. It utilizes the charge pump topology to boost V IN to a regulated output voltage. Regulation is obtained by sensing the output voltage through an internal resistor divider. A switched doubling circuit enables the charge pump when the feedback voltage is lower than the trip point of the internal comparator, and vice versa. When the charge pump is enabled, a two-phase non-overlapping clock activates the charge pump switches. Operation This kind of converter uses capacitors to store and transfer energy. Since the capacitors can t change their voltage level abruptly, the voltage ratio of V OUT over V IN is limited to some range. Capacitive voltage conversion is obtained by switching a capacitor periodically. It first charges the capacitor by connecting it across a voltage source and then connects it to the output. Referring to Fig. 0, during the on state of internal clock, Q and Q are closed, which charges C to V IN level. During the off state, Q and Q are closed. The output voltage is V IN plus V C, that is, V IN. V IN Q Q C Q Q Fig. 0 The circuit of charge pump V OUT Short Circuit/Thermal Protection AIC88 owns a built-in short circuit current limiting as well as an over temperature protection. During the short circuit condition, the output current is automatically constrained at approximately 00mA. This short circuit current will cause a rise in the internal IC junction temperature. When the die temperature exceeds 50 C, the thermal protection will shut the charge pump switching operation down and the die temperature will reduce afterwards. Once the die temperature drops below 5 C, the charge pump switching circuit will re-start. If the fault doesn t eliminate, the above protecting operation will repeat again and again. It allows AIC88 to continuously work at short circuit condition without damaging the device. Shutdown In shutdown mode, the output is disconnected from input. The input current gets extremely low since most of the circuitry is turned off. Due to high impedance, shutdown pin can t be floated. Efficiency Referring to Fig. and Fig. here shows the circuit of charge pump at different states of operation. R DS-ON is the resistance of the switching element at conduction. ESR is the equivalent series resistance of the flying capacitor C. I ON- AVE and I OFF-AVE are the average current during on state and off state, respectively. D is the duty cycle, which means the proportion the on state takes. Let s take advantage of conversation of charge for capacitor C. Assume that the 7

8 AIC88 capacitor C has reached its steady state. The amount of charge flowing into C during on state is equal to that flowing out of C at off state. I I ON AVE DT = IOFF AVE ( D)T () ON-AVE I I IN OUT = I = I = I D = I ( D) () ON-AVE = I I IN = I OUT D + I ON-AVE OFF-AVE D OFF-AVE (- D) ( D) ( D) () For AIC88, the controller takes the PWM (Pulse Width Modulation) control strategy. When the duty cycle is limited to 0.5, there will be: OFF-AVE OFF-AVE ION -AVE 0.5 T = IOFF-AVE ( 0.5) T Fig. The off state of charge pump circuit External Capacitor Selection Three external capacitors,, and C FLY, determine AIC88 performances, in the aspects of output ripple voltage, charge pump strength and transient. Optimum performance can be obtained by the use of ceramic capacitors with low ESR. Due to high ESR, capacitors of tantalum and aluminum are not recommended for charge pump application. To reduce noise and ripple, a low ESR ceramic capacitor, is recommended for and. The value of determines the amount of output ripple voltage. An output capacitor with larger value results in smaller ripple. I ON-AVE = IOFF-AVE C FLY is critical for the strength of charge pump. The larger C FLY is, the larger output...(5) current and According to the equation (), we know that as long as the flying capacitor C is at steady state, the input current is twice the output current. The efficiency of charge pump is given below: smaller ripple voltage obtain. However, large and are expected when a large C FLY applies. The ratio of (as well as ) to C FLY should be approximately 0:. η IOUT IOUT = = =...(6) IIN IOUT The value of capacitors, which is used under V IN ION Q Q R DS-ON ESR Q C Q R DS-ON V OUT Fig. The on state of charge pump circuit V IN Q Q R DS-ON I OFF R DS-ON ESR Q C Q V OUT operation conditioin, determines the performance of a charge pump converter. And two factors, as follows, affect the capacitance of capacitor.. Material: Ceramic capacitors of different materials, such as X7R, X5R, Z5U and Y5V, have different tolerance in temperature and differnet cpacitance loss. For example, a X7R or X5R type of capacitor can retain most of the capacitance at temperature from -0 C to 85 C, but a Z5U or Y5V type will lose most of the capacitance at that temperature range.. Package Size: A ceramic capacitor with large volume (0805), gets a lower ESR than a small one (060). Therefore, large devices 8

9 AIC88 can improve more transient response than small ones. Table lists the recommended components for AIC88 application. Table. Bill of Material Designator Type Part Description Vendor Phone TAIYO µ JMK07BJ05KA YUDEN (0) 79755~9 C FLY 0.µ EMK07BJ0KA TAIYO YUDEN (0) 79755~9 Layout Considerations Due to the switching frequency and high transient current of AIC88, careful consideration of PCB layout is necessary. To achieve the best performance of AIC88, minimize the distance between every two components and also minimize every connection length with a maximum trace width. Make sure each device connects to immediate ground plane. Fig. to Fig. 5 show the recommended layout. µ JMK07BJ05KA TAIYO YUDEN (0) 79755~9 Fig. Top layer Fig. Bottom layer Fig. 5 Topover layer 9

10 AIC88 APPLICATION EXAMPLES CAP+ 6 µf C FLY 5 0.µF CAP- U AIC88 µf V U AIC88 CAP+ 6 5 CAP- C FLY 0.µF Fig. 6 Parallel Two AIC88 to Obtain the Regulated 5V Output with large output current. 5Vout Vin Cin uf Enable U C+ C- AIC Cfly 0.uF Cout uf R 7 Flash Control R 9. Q Si0 Fig. 7 Flash WLED Application Vin Cin uf Enable U AIC88 C+ C- 6 5 Cfly 0.uF Cout uf R 7 R k 5Vout R.7 Q Si0 Flash U AIC88 C+ C- 6 5 Cfly 0.uF D C 0.uF Fig. 7 Flash WLED Application with Parallel Two AIC88 0

11 AIC88 PHYSICAL DIMENSIONS (unit: mm) SOT--6 D SYMBOL MIN MAX A A E E 0.5 A e e L L θ c b c D E A A E b A e 0.95 BSC e.90 BSC L L 0.60 REF θ 0 8 Note: Information provided by AIC is believed to be accurate and reliable. However, we cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AIC product; nor for any infringement of patents or other rights of third parties that may result from its use. We reserve the right to change the circuitry and specifications without notice. Life Support Policy: AIC does not authorize any AIC product for use in life support devices and/or systems. Life support devices or systems are devices or systems which, (I) are intended for surgical implant into the body or (ii) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user.