A S1 3 2 2 L o w Vo lt a g e, M i c ro p o w e r, D C- DC St ep - U p C o n v e r te r s 1 General Description 2 Key Features The AS1322A and the AS1322B are synchronous, fixed frequency, very high-efficiency DC-DC boost converters capable of supplying 3.3V at 150mA from a single AA-supply. Compact size and minimum external parts requirements make these devices perfect for modern portable devices. 95% Efficiency High-speed switching frequency (1.2MHz) and internally compensated PWM current mode design provide highly-reliable DCDC conversion, especially when driving white LEDs. Delivers 220mA @ 5.0V (from Two AA Cells) The converters are available as the standard products listed in Table 1. Low Start-Up Voltage: 0.85V Single-Cell Operation Delivers 160mA @ 3.3V (from Single AA Cell) Delivers 570mA @ 3.3V (from Two AA Cells) High-Speed Fixed-Frequency: 1.2MHz Table 1. Standard Products Internal PMOS Synchronous Rectifier Model Light Load Switching AS1322A Automatic Powersave Operation AS1322B Continuous Switching Automatic Powersave Operation (AS1322A) Continuous Switching at Light Loads (AS1322B) Anti-Ringing Control Minimizes EMI The devices contain two internal MOSFET switches: one NMOS switch and one PMOS synchronous rectifier. Logic Controlled Shutdown (< 1µA) Anti-ringing control circuitry reduces EMI by damping the inductor in discontinuous mode, and the devices exhibit extremely low quiescent current (< 1µA) in shutdown. Output Range: 2.5 to 5.0V 6-pin TSOT-23 Package In shutdown mode the battery is connected to the output and VOUT is held at approximately VIN - 0.6V. The AS1322 is available in a 6-pin TSOT-23 package. 3 Applications Figure 1. Typical Application Diagram – Single Cell to 3.3V Synchronous Boost Converter The AS1322 is ideal for low-power applications where ultra-small size is critical as in medical diagnostic equipment, hand-held instruments, pagers, digital cameras, remote wireless transmitters, MP3 players, LCD bias supplies, cordless phones, GPS receivers, and PC cards. L1 4.7µH 1 SW 6 AA Battery 5 VOUT VIN C1 10µF On Off AS1322 4 C2 10µF 3 SHDNN FB 2 www.ams.com/DC-DC_Step-Up/AS1322 R1 1.02MΩ 1% VOUT 3.3V 160mA GND Revision 1.10 R2 604kΩ 1% 1 - 18 AS1322 Datasheet - P i n A s s i g n m e n t s 4 Pin Assignments Figure 2. Pin Assignments (Top View) SW 1 GND 2 6 VIN AS1322 FB 3 5 VOUT 4 SHDNN 4.1 Pin Descriptions Table 2. Pin Descriptions Pin Number Pin Name 1 SW 2 GND 3 FB 4 SHDNN 5 VOUT 6 VIN www.ams.com/DC-DC_Step-Up/AS1322 Description Switch Pin. Connect an inductor between this pin and VIN. Keep the PCB trace lengths as short and wide as is practical to reduce EMI and voltage overshoot. If the inductor current falls to zero, or pin SHDNN is low, an internal 100Ω anti-ringing switch is connected from this pin to VIN to minimize EMI. Note: An optional Schottky diode can be connected between this pin and VOUT. Signal and Power Ground. Provide a short, direct PCB path between this pin and the negative side of the output capacitor(s). Feedback Pin. Feedback input to the gm error amplifier. Connect a resistor divider tap to this pin. The output voltage can be adjusted from 2.5 to 5V by: VOUT = 1.23V[1 + (R1/R2)] Shutdown Pin. Logic controlled shutdown input. 1 = Normal operation, 1.2MHz typical operating frequency. 0 = Shutdown; quiescent current <1µA. If SHDNN is undefined, pin SW may ring. Note: In a typical application, SHDNN should be connected to VIN through a 1MΩ pull-up resistor. Output Voltage Sense Input and Drain of the Internal PMOS Synchronous Rectifier. Bias is derived from VOUT when VOUT exceeds VIN. PCB trace length from VOUT to the output filter capacitor(s) should be as short and wide as is practical. VOUT is held at approximately VIN - 0.6V during shutdown. Input Voltage. The AS1322 gets its start-up bias from VIN unless VOUT exceeds VIN, in which case the bias is derived from VOUT. Thus, once started, operation is completely independent from VIN. Operation is only limited by the output power level and the internal series resistance of the supply. Revision 1.10 2 - 18 AS1322 Datasheet - A b s o l u t e M a x i m u m R a t i n g s 5 Absolute Maximum Ratings Stresses beyond those listed in Table 3 may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in Section 6 Electrical Characteristics on page 4 is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 3. Absolute Maximum Ratings Parameter Min Max Units VIN to GND -0.3 7 V SHDNN, SW to GND -0.3 7 V FB to GND -0.3 5 V VOUT -0.3 7 V Operating Temperature Range -40 +85 ºC Storage Temperature Range -65 +125 ºC Package Body Temperature Moisture Sensitive Level www.ams.com/DC-DC_Step-Up/AS1322 +260 1 ºC Notes The reflow peak soldering temperature (body temperature) specified is in accordance with IPC/ JEDEC J-STD-020 “Moisture/Reflow Sensitivity Classification for Non-Hermetic Solid State Surface Mount Devices”. The lead finish for Pb-free leaded packages is matte tin (100% Sn). Represents an unlimited floor life time Revision 1.10 3 - 18 AS1322 Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s 6 Electrical Characteristics TAMB = -40 to +85ºC, VIN = +1.2V, VOUT = +3.3V, VSHDNN = +1.2V (unless otherwise specified). Typ values @ TAMB = +25ºC. Table 4. Electrical Characteristics Symbol Parameter Conditions Min Minimum Start-Up Voltage ILOAD = 1mA Minimum Operating Voltage SHDNN = VIN Output Voltage Adjust Range TAMB = 25ºC 2.5 VFB Feedback Voltage TAMB = TMIN to TMAX 1.192 IFB Feedback Input Current VFB = 1.25V IQPWS Quiescent Current (Powersave Operation) VFB = 1.4V , AS1322A only 30 50 µA IQSHDNN Quiescent Current (Shutdown) VSHDNN = 0V 0.01 1 µA 1 2 Typ Max Units 0.85 1 V 0.65 0.85 V 5 V 1.268 V 1.23 1 3 3 nA IQ Quiescent Current (Active) VFB = 1.4V , AS1322B only 150 300 µA INMOSSWL NMOS Switch Leakage VSW = 5V 0.1 5 µA IPMOSSWL PMOS Switch Leakage VSW = 0V 0.1 5 µA RONNMOS NMOS Switch On Resistance VOUT = 3.3V 0.35 0.8 VOUT = 5V 0.20 0.7 RONPMOS PMOS Switch On Resistance VOUT = 3.3V 0.45 0.8 VOUT = 5V 0.30 0.7 INMOS NMOS Current Limit VIN = 2.5V 850 mA IPS Powersave Operation Current Threshold AS1322A only 3 mA Max Duty Cycle VFB = 1V, TAMB = TMIN to TMAX 80 87 % TAMB = 25ºC 0.95 1.2 1.5 TAMB = TMIN to TMAX 0.85 1.2 1.5 fSW Switching Frequency VSHDNNH SHDNN Input High VSHDNNL SHDNN Input Low ISHDNN SHDNN Input Current 2 1 VSHDNN = 5.0V Ω Ω MHz V 0.01 0.35 V 1 µA 1. Minimum VIN operation after start-up is only limited by the battery’s ability to provide the necessary power as it enters a deeply discharged state. 2. Specification is guaranteed by design and not 100% production tested. 3. IQPWS is measured at VOUT. Multiply this value by VOUT/VIN to get the equivalent input (battery) current. Note: All limits are guaranteed. The parameters with min and max values are guaranteed with production tests or SQC (Statistical Quality Control) methods. www.ams.com/DC-DC_Step-Up/AS1322 Revision 1.10 4 - 18 AS1322 Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s 7 Typical Operating Characteristics Figure 3. Powersave mode threshold vs. VIN, VOUT = 3.0V Figure 4. Efficiency vs. Output Current, VOUT = 3.3V 100 90 25 Efficiency (%) . Output Current (mA) . 30 20 15 10 5 VIN = 2.4V 80 VIN = 1.5V 70 VIN = 1.0V 60 50 40 30 0 0.5 0.75 1 1.25 1.5 1.75 2 1 2.25 2.5 10 3.36 3.5 3.34 3 3.32 3.3 3.28 3.26 2.5 2 1.5 1 0.5 0 -25 0 25 50 75 100 0 0.5 1 Temperature (°C) 1.5 900 1.4 . 1000 800 1.3 Output Current (mA) Startup Voltage (V) . 2 2.5 3 3.5 Figure 8. Output Current vs. Battery Voltage; VOUT = 3.3V, 3% Tolerance 1.6 700 1.2 1.1 1 5V 3.3V 0.8 1.5 Battery Voltage (V) Figure 7. Startup Voltage vs. Output Current; 0.9 1000 Figure 6. Output Voltage vs. Battery Voltage; VOUT = 3.3V, IOUT = 10mA Output Voltage (V) . Output Voltage (V) . Figure 5. Output Voltage vs. Temperature; VOUT = 3.3V, IOUT = 10mA 3.24 -50 100 Output Current (mA) Battery Voltage (V) 0.7 600 500 400 300 200 100 0.6 0 0.1 1 10 100 0.5 Output Current (mA) www.ams.com/DC-DC_Step-Up/AS1322 1 1.5 2 2.5 3 Battery Voltage (V) Revision 1.10 5 - 18 AS1322 Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s Figure 9. Output Current vs. Battery Voltage; VOUT = 5.0V, 3% ToleranceVOUT = 3.3V, TAMB = 25ºC Figure 10. No Load Battery Current vs. VBATT 900 1000 Battery Current (µA) . . 800 Output Current (mA) 700 600 500 400 300 200 100 100 0 10 0.5 1 1.5 2 2.5 3 3.5 4 1.2 1.4 1.6 1.8 Battery Voltage (V) 2 2.2 2.4 2.6 2.8 Figure 12. SW Pin Fixed Frequency Continuous Current VIN = 1.3V, VOUT = 3.3V, L = 10µH, C = 10µF, IOUT = 100mA 1V/Div 100ns/Div 100ns/Div 40mA 60mA 100mV/Div VOUT(AC) 1mA 100mA 100mV/Div Figure 14. Fixed Frequency vs. Powersave Operation VIN = 1.3V, VOUT = 3.3V, L = 10µH, C = 10µF IOUT Figure 13. VOUT Transient Response. VIN = 1.3V, VOUT = 3.3V, L = 10µH, C = 10µF VOUT(AC) 0V VSW 0V VSW 1V/Div Figure 11. SW Pin Antiringing Operation VIN = 1.3V, VOUT = 3.3V, L = 10µH, C = 10µF, IOUT = 5mA IOUT 3 Battery Voltage (V) 100µs/Div 10ms/Div Parts used for measurements: 10µH (MOS6020-103ML) Inductor, 10µF (GRM31CR70J106KA01L) CIN and COUT www.ams.com/DC-DC_Step-Up/AS1322 Revision 1.10 6 - 18 AS1322 Datasheet - D e t a i l e d D e s c r i p t i o n 8 Detailed Description The AS1322/AS1322B can operate from a single-cell input voltage (VIN) below 1V, and feature fixed frequency (1.2MHz) and current mode PWM control for exceptional line- and load-regulation. With low RDS(ON) and gate charge internal NMOS and PMOS switches, the devices maintain high-efficiency from light to heavy loads. Modern portable devices frequently spend extended time in low-power or standby modes, switching to high power-drain only when certain functions are enabled. The AS1322A and the AS1322B are ideal for portable devices since they maintain high-power conversion efficiency over a wide output power range, thus increasing battery life in these types of devices. In addition to high-efficiency at moderate and heavy loads, the AS1322A includes an automatic powersave mode that improves efficiency of the power converter at light loads. The powersave mode is initiated if the output load current falls below a factory programmed threshold (see Figure 3 on page 5). Note: The AS1322B does not support powersave mode and provides continuous operation at light loads, eliminating low-frequency VOUT ripple at the expense of light load efficiency. Figure 15. AS1322 - Block Diagram L1 4.7µH 1.5V Single Cell 6 VIN Start Up OSC CIN 1µF 1 SW 2.3V – A B VOUT Good A/B MUX PWM Control 1.2MHz Ramp Generator VOUT CFF* Current Sense Σ Slope Compensator + 0.45Ω 0.35Ω Sync Drive Control AS1322 + PWM – Comp – 4 SHDNN Shutdown Control Powersave Shutdown Powersave Operation Control RC 80kΩ CC 150pF 3.3V Output 5 3 – gm Error Amp + R1 1.02MΩ 1% COUT 4.7µF FB CP2 2.5pF R2 640kΩ 1% 1.23V Ref 2 GND * Optional 8.1 Low-Voltage Start-Up The AS1322 requires VIN of only 0.85V (typ) or higher to start up. The low-voltage start-up circuitry controls the internal NMOS switch up to a maximum peak inductor current of 850mA (typ), with 1.5ms (approx.) off-time during start-up, allowing the devices to start up into an output load. With a VOUT > 2.3V, the start-up circuitry is disabled and normal fixed-frequency PWM operation is initiated. In this mode, the AS1322 operates independent of VIN, allowing extended operating time as the battery can drop to several tenths of a volt without affecting output regulation. The limiting factor for the application is the ability of the battery to supply sufficient energy to the output. www.ams.com/DC-DC_Step-Up/AS1322 Revision 1.10 7 - 18 AS1322 Datasheet - D e t a i l e d D e s c r i p t i o n 8.2 Low-Noise Fixed-Frequency Operation 8.2.1 Oscillator The AS1322 switching frequency is internally fixed at 1.2MHz allowing the use of very small external components. 8.2.2 Error Amplifier The integrated error amplifier is an internally compensated trans-conductance (gm) type (current output). The internal 1.23V reference voltage is compared to the voltage at pin FB to generate an error signal at the output of the error amplifier. A voltage divider from VOUT to GND programs the output voltage from 2.5 to 5V via pin FB as: VOUT = 1.23V(1 + (R1/R2)) 8.2.3 (EQ 1) Current Sensing A signal representing the internal NMOS-switch current is summed with the slope compensator. The summed signal is compared to the error amplifier output to provide a peak current control command for the PWM. Peak switch current is limited to approximately 850mA independent of VIN or VOUT. 8.2.4 Zero Current Comparator The zero current comparator monitors the inductor current to the output and shuts off the PMOS synchronous rectifier once this current drops to 20mA (approx.). This prevents the inductor current from reversing polarity and results in improved converter efficiency at light loads. 8.2.5 Anti-Ringing Control Anti-ringing control circuitry prevents high-frequency ringing on pin SW as the inductor current approaches zero. This is accomplished by damping the resonant circuit formed by the inductor and the capacitance on pin SW (CSW). 8.3 Powersave Operation (AS1322A) In light load conditions, the integrated powersave feature removes power from all circuitry not required to monitor VOUT. When VOUT has dropped approximately 1% from nominal, the AS1322A powers up and begins normal PWM operation. COUT (see Figure 15 on page 7) recharges, causing the AS1322A to re-enter powersave mode as long as the output load remains below the powersave threshold. The frequency of this intermittent PWM is proportional to load current; i.e., as the load current drops further below the powersave threshold, the AS1322A turns on less frequently. When the load current increases above the powersave threshold, the AS1322A will resume continuous, seamless PWM operation. Notes: 1. An optional capacitor (CFF) between pins VOUT and FB in some applications can reduce VOUTp-p ripple and input quiescent current during powersave mode. Typical values for CFF range from 15 to 220pF. 2. In powersave mode the AS1322A draws only 30µA from the output capacitor(s), greatly improving converter efficiency. 8.4 Shutdown When pin SHDNN is low the AS1322 is switched off and <1µA current is drawn from battery; when pin SHDNN is high the device is switched on. If SHDNN is driven from a logic-level output, the logic high-level (on) should be referenced to VOUT to avoid intermittently switching the device on. Note: If pin SHDNN is not used, it should be connected directly to pin OUT. VOUT is held at approximately VIN - 0.6V during shutdown. In shutdown the battery input is connected to the output through the inductor and the internal synchronous rectifier P-FET. Due to the body diode of the internal synchronous rectifier PFET, VOUT is held at approximately VIN - 0.6V during shutdown. This allows the input battery to provide backup power for devices such as an idle microcontroller, memory, or real-time-clock, without the usual diode forward drop. In this way a separate backup battery is not needed. www.ams.com/DC-DC_Step-Up/AS1322 Revision 1.10 8 - 18 AS1322 Datasheet - A p p l i c a t i o n I n f o r m a t i o n 9 Application Information The AS1322 is perfectly suited for LED matrix displays, bar-graph displays, instrument-panel meters, dot matrix displays, set-top boxes, white goods, professional audio equipment, medical equipment, industrial controllers to name a few applications. Along with Figure 1 on page 1, Figures 16-19 depict a few of the many applications for which the AS1322 converters are perfectly suited. Figure 16. Single AA Cell to 3.3V Synchronous Boost Converter with Load Disconnect in Shutdown L1 4.7µH D1 1 SW 5 6 AA Battery VIN C1 4.7µF AS1322 On Off 4 VOUT 3.3V, 160mA VOUT C2 4.7µF R3 510kΩ R1 1.02MΩ 1% 3 SHDNN FB 2 R2 604kΩ 1% GND Q1 R3 510kΩ Figure 17. Single Lithium Cell to 5V, 250mA 2Ω Optional Snubber 100nF L1 4.7µH D1 1 SW 5 6 Lithium Battery VIN C1 4.7µF On Off AS1322 R1 1.02MΩ 1% C3 100pF 3 4 SHDNN FB 2 www.ams.com/DC-DC_Step-Up/AS1322 VOUT C2 4.7µF GND Revision 1.10 R2 332kΩ 1% 9 - 18 AS1322 Datasheet - A p p l i c a t i o n I n f o r m a t i o n Figure 18. Single AA Cell to ±3V Synchronous Boost Converter C3 1µF L1 4.7µH 1 SW AA Battery C1 4.7µF VOUT1 3V, 90mA 5 6 VOUT VIN On Off 4 C2 4.7µF R1 1.02MΩ 1% AS1322 3 D1 FB SHDNN 2 D2 C4 10µF R2 750kΩ 1% GND VOUT2 -3V, 10mA Figure 19. Single AA Cell to 2.5V Synchronous Boost Converter L1 4.7µH D1 1 SW 5 6 AA Battery C1 10µF On Off R1 1.02MΩ 1% AS1322 C2 10µF 3 4 FB SHDNN 2 www.ams.com/DC-DC_Step-Up/AS1322 VOUT 2.5V, 230mA VOUT VIN GND Revision 1.10 R2 1.02MΩ 1% 10 - 18 AS1322 Datasheet - A p p l i c a t i o n I n f o r m a t i o n 9.1 Output Voltage Ripple The AS1322 is designed to work at high efficiency. In order to reduce the output ripple the following improvements are recommended: Use a higher output capacitor, up to 44µF and a higher input capacitor (22µF). Use smaller values for the resistor divider. R1 should be about 300kΩ. To avoid a high leakage current from pin VOUT through the resistor divider to GND, R1 should not be less than 100kΩ. To reduce the output ripple it’s also possible to speed up the feedback loop. To achieve this, place a 22pF (C4 in Figure 20) capacitor in parallel to R1. Via C4 the fast transients are shorted to the FB pin and the feedback loop is even faster. A 1MΩ resistor for R1 slows down the FB loop. Due to noise and to their non linear behavior, the use of potentiometers is not recommended. Figure 20. AS1322 - Typical Application for lower Output Voltage Ripple L1 4.7µH 1 2xAA Battery SW VOUT VIN C1 22µF C4 22pF AS1322 On Off VOUT = 2.8V 5 6 R1 250kΩ C2 22µF C3 22µF 3 4 FB SHDNN 2 GND R2 196kΩ Note: For correct measurements of the output ripple connect the oscilloscope probe as close as possible to the positive plate of the COUT and connect the GND of the oscilloscope probe to the negative plate of the COUT. This will reduce the inductive coupling and will deliver a more accurate measurement result. The output ripple is getting higher as VIN is getting closer to VOUT. Figure 21 shows that the above mentioned improvements reduce the output voltage ripple. If VIN is higher than VOUT the AS1322 stops switching and VIN is connected to VOUT via the inductor and the internal P-FET. Figure 21. Output Voltage Ripple vs. Input Voltage; VOUT = 2.8V, IOUT = 0.8mA Output Voltage Ripple (mVpp) 125 Cout = 44µF Cout = 66µF 100 Cout = 44µF + C4 = 22pF 75 50 25 0 0.5 1 1.5 2 2.5 3 3.5 Input Voltage (V) www.ams.com/DC-DC_Step-Up/AS1322 Revision 1.10 11 - 18 AS1322 Datasheet - A p p l i c a t i o n I n f o r m a t i o n 9.2 External Component Selection 9.2.1 Inductor Selection The fast switching frequency (1.2MHz) of the AS1322 allows for the use of small surface mount or chip inductor for the external inductor (see Figure 15 on page 7). The required minimum values for the external inductor are: 3.3µH for applications ≤ 3.6V 4.7µH for applications > 3.6V Larger inductor values allow greater output current capability by reducing the inductor ripple current. Increasing the inductance above 10µH will increase size while providing negligible improvement in output current capability. The approximate output current capability of the AS1322 versus inductor value is given in: V IN ⋅ D I OUT ( MAX ) = η ⋅ I P – ------------------ ⋅ ( 1 – D ) f ⋅ L ⋅ 2 (EQ 2) Where: η is the estimated efficiency; IP is the peak current limit value (0.6A); VIN is the input voltage; D is the steady-state duty ratio = (VOUT - VIN)/VOUT; f is the switching frequency (1.2MHz typ); L is the inductor value. The inductor current ripple is typically set for 20 to 40% of the maximum inductor current (IP). High-frequency ferrite core inductor materials reduce frequency dependent power losses compared to less expensive powdered iron types, which result in improved converter efficiency. 2 The inductor should have low ESR to reduce the I R power losses, and must be able to handle the peak inductor current without saturating. Molded chokes and some chip inductors normally do not have enough core to support the peak inductor currents of the AS1322 (850mA typ). To minimize radiated noise, use a toroid, pot core, or shielded bobbin inductor. Table 5. Recommended Inductors Part Number L DCR Current Rating Dimensions (L/W/T) MOS6020-103ML 10µH 93mΩ 1A 6.8x6.0x2.4mm MOS6020-472ML 4.7µH 50mΩ 1.5A 6.8x6.0x2.4mm MOS6020-332ML 3.3µH 46mΩ 1.8A 6.8x6.0x2.4mm CDRH4D18-100 10µH 200mΩ 0.61A 6.9x5.0x2.0mm CDRH4D18-6R8 6.8µH 200mΩ 0.76A 6.9x5.0x2.0mm CR43-6R8 6.8µH 131.2mΩ 0.95A 4.8x4.3x3.5mm CDRH4D18-4R7 4.7µH 162mΩ 0.84A 6.9x5.0x2.0mm www.ams.com/DC-DC_Step-Up/AS1322 Revision 1.10 Manufacturer Coilcraft www.coilcraft.com Sumida www.sumida.com 12 - 18 AS1322 Datasheet - A p p l i c a t i o n I n f o r m a t i o n Figure 22. Efficiency Comparison of Different Inductors, VIN = 1.5V, VOUT = 3.3V 92 90 85 90 80 88 Efficiency (%) Efficiency (%) 75 70 65 60 10uH - Coi l cr af t (M OS6020-103M L) 55 10uH - Sumi da(CDRH4D18-100) 84 82 10uH - Coi l cr af t (M OS6020-103M L) 80 6. 8uH - Sumi da(CDRH4D18-6R8) 50 86 6. 8uH - Sumi da(CR43-6R8) 10uH - Sumi da(CDRH4D18-100) 6. 8uH - Sumi da(CDRH4D18-6R8) 6. 8uH - Sumi da(CR43-6R8) 4. 7uH - Coi l cr af t(M OS6020-472M L) 45 78 4. 7 uH - Sumi da(CDRH4D18-4R7) 4. 7uH - Coi l cr af t (M OS6020-472M L) 4. 7 uH - Sumi da(CDRH4D18-4R7) 3. 3 uH - Coi l c r af t (M OS6020-332M L) 3. 3 uH - Coi l cr af t (M OS6020-332M L) 40 0.1 1 10 10 Output Current (mA) 9.2.2 Ser i es 8 76 Output Current (mA) 100 Output Capacitor Selection Low ESR capacitors should be used to minimize VOUT ripple. Multi-layer ceramic capacitors are recommended since they have extremely low ESR and are available in small footprints. A 2.2 to 10µF output capacitor is sufficient for most applications. Larger values up to 22µF may be used to obtain extremely low output voltage ripple and improve transient response. An additional phase lead capacitor may be required with output capacitors larger than 10µF to maintain acceptable phase margin. X5R and X7R dielectric materials are recommended due to their ability to maintain capacitance over wide voltage and temperature ranges. Table 6. Recommended Output Capacitor Part Number C TC Code Rated Voltage Dimensions (L/W/T) JMK212BJ226MG-T 22µF ±20% X5R 6.3V 2x1.3x1.3mm Manufacturer Taiyo Yuden www.t-yuden.com Input Capacitor Selection. Low ESR input capacitors reduce input switching noise and reduce the peak current drawn from the battery. Ceramic capacitors are recommended for input decoupling and should be located as close to the device as is practical. A 4.7µF input capacitor is sufficient for most applications. Larger values may be used without limitations. Table 7. Recommended Input Capacitor Part Number C TC Code Rated Voltage Dimensions (L/W/T) GRM31CR70J106KA01L 10µF ±10% X7R 6.3V 3.2x1.6x1.6mm Manufacturer Murata www.murata.com Diode Selection. A Schottky diode should be used to carry the output current for the time it takes the PMOS synchronous rectifier to switch on. For VOUT < 4.5V a Schottky diode is optional, although using one will increase device efficiency by 2 to 3%. Note: Do not use ordinary rectifier diodes, since the slow recovery times will compromise efficiency. www.ams.com/DC-DC_Step-Up/AS1322 Revision 1.10 13 - 18 AS1322 Datasheet - A p p l i c a t i o n I n f o r m a t i o n 9.3 PCB Layout Guidelines The high-speed operation of the AS1322 requires proper layout for optimum performance. Figure 23 shows the recommended component layout. A large ground pin copper area will help to lower the device temperature. A multi-layer board with a separate ground plane is recommended. Traces carrying large currents should be direct. Trace area at pin FB should be as small as is practical. The lead-length to the battery should be as short as is practical. Figure 23. Recommended Single-Layer Component Placement Optional VIN 6 1 SW AS1322 VIN R2 2 GND VOUT 5 CIN SHDNN 3 FB R1 SHDNN 4 COUT VOUT www.ams.com/DC-DC_Step-Up/AS1322 Revision 1.10 14 - 18 AS1322 Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s 10 Package Drawings and Markings The device is available in a 6-pin TSOT-23 package. Figure 24. 6-pin TSOT-23 Package www.ams.com/DC-DC_Step-Up/AS1322 Revision 1.10 15 - 18 AS1322 Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s Figure 25. 6-pin TSOT-23 Marking Pin1 Top ZZZZ Bottom XXXX Pin1 Package Code: ZZZZ - Marketingcode XXXX - encoded Datecode www.ams.com/DC-DC_Step-Up/AS1322 Revision 1.10 16 - 18 AS1322 Datasheet 11 Ordering Information The device is available as the standard products listed in Table 8. Table 8. Ordering Information Ordering Code Marking Description Delivery Form Package AS1322A-BTTT ASKQ Low Voltage, Micropower, DC-DC Step-Up Converter with Automatic Powersave Operation Tape and Reel 6-pin TSOT-23 AS1322B-BTTT ASKZ Low Voltage, Micropower, DC-DC Step-Up Converter with Continuous Switching Tape and Reel 6-pin TSOT-23 Note: All products are RoHS compliant. Buy our products or get free samples online at ICdirect: http://www.ams.com/ICdirect Technical Support is found at http://www.ams.com/Technical-Support For further information and requests, please contact us mailto:[email protected] or find your local distributor at http://www.ams.com/distributor www.ams.com/DC-DC_Step-Up/AS1322 Revision 1.10 17 - 18 AS1322 Datasheet - O r d e r i n g I n f o r m a t i o n Copyrights Copyright © 1997-2010, ams AG, Tobelbaderstrasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. All products and companies mentioned are trademarks or registered trademarks of their respective companies. Disclaimer Devices sold by ams AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. ams AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. ams AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with ams AG for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are specifically not recommended without additional processing by ams AG for each application. For shipments of less than 100 parts the manufacturing flow might show deviations from the standard production flow, such as test flow or test location. The information furnished here by ams AG is believed to be correct and accurate. However, ams AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of ams AG rendering of technical or other services. Contact Information Headquarters ams AG Tobelbaderstrasse 30 A-8141 Unterpremstaetten, Austria Tel: +43 (0) 3136 500 0 Fax: +43 (0) 3136 525 01 For Sales Offices, Distributors and Representatives, please visit: http://www.ams.com/contact www.ams.com/DC-DC_Step-Up/AS1322 Revision 1.10 18 - 18