AS1332 D a ta s h e e t 6 5 0 m A , St e p - D o w n D C - D C C o n v e r t e r f o r R F P o w e r A m p l i f i e r s 1 General Description 2 Key Features The AS1332 is a step-down DC-DC converter designed to power radiofrequency (RF) power amplifiers (PAs) from a single Li-Ion battery. The device also achieves high-performance in mobile phones and similar RF PA applications. The AS1332 steps down an input voltage of 2.7V to 5.5V to output voltages ranging from 1.3V to 3.16V. Using a VCON analog input, the output voltage is set for controlling power levels and efficiency of the RF PA. The RF interferences are minimized due to the fixedfrequency PWM operation. The battery consumption is reduced to 0.01µA (typ.) during shutdown. Because of the high switching frequencies (2 MHz) tiny surface-mount components can be used. Additional to the small size the amount is also small. Only three external components are required, an inductor and two ceramic capacitors. The AS1332 is available in a 8-pin WL-CSP. ! PWM Switching Frequency: 2MHz ! Single Lithium-Ion Cell Operation (2.7V to 5.5V) ! Dynamic Programmable Output Voltage (1.3V to 3.16V) ! Maximum load capability of 650mA ! High Efficiency (96% Typ at 3.6VIN, 3.16VOUT at 400mA) from internal synchronous rectification ! Current Overload Protection ! Thermal Overload Protection ! Soft Start ! 8-pin WL-CSP 3 Applications The AS1332 is an ideal solution for cellular phones, hand-held radios, RF PC cards, and battery powered RF devices. Figure 1. Typical Application Circuit VIN 2.7V to 5.5V VDD PVIN 10 µF 3.3 µH VOUT 1.3V to 3.16V SW EN AS1332 VOUT = 2.5 x VCON FB 4.7 µF VCON 0.52V to 1.27V www.austriamicrosystems.com VCON PGND Revision 1.01 AGND 1 - 19 AS1332 Datasheet - P i n A s s i g n m e n t s 4 Pin Assignments Figure 2. Pin Configuration PVIN A1 VDD B1 EN C1 Top View Bottom View SW SW A2 C2 A3 PGND B3 AGND C3 FB PVIN A3 AGND B3 FB C3 VCON A2 C2 A1 PVIN B1 VDD C1 EN VCON Pin Descriptions Table 1. Pin Descriptions Pin Name PVIN Pin Number Description A1 VDD B1 EN C1 VCON FB AGND PGND C2 C3 B3 A3 SW A2 +2.7V to + 5.5V Power Supply Voltage. Input to the internal PFET switch. +2.7V to + 5.5V Analog Supply Input. Bypass this pin to GND with a ≥10µF capacitor. Active-High Enable Input. Set this digital input high for normal operation. For shutdown, set low. Voltage Control Analog Input. VCON controls VOUT. Feedback Pin. Connect to the output at the output filter capacitor. Analog and Control Ground Power Ground Switch Pin. Switch node connection to the internal PFET switch and NFET synchronous rectifier. Limit specification of the AS1332. www.austriamicrosystems.com Revision 1.01 2 - 19 AS1332 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 2 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 Electrical Characteristics on page 4 is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 2. Absolute Maximum Ratings Parameter Min Max Units VDD, PVIN to AGND -0.3 +7 V PGND to AGND -0.3 +0.3 V EN, FB, VCON AGND - 0.3 VDD + 0.3 V SW PGND - 0.3 PVIN + 0.3 V PVIN to VDD -0.3 +0.3 V Operating Temperature Range -40 +85 ºC +150 ºC +150 ºC +260 ºC 2 kV 5.5 V 650 mA +125 ºC Junction Temperature (TJ-MAX) Storage Temperature Range -65 Maximum Lead Temperature (soldering, 10sec) Comments 7V max ESD Rating Human Body Model HBM MIL-Std. 883E 3015.7 methods Operating Ratings Input Voltage Range 2.7 Recommended Load Current Junction Temperature (TJ) Range Ambient Temperature (TA) Range www.austriamicrosystems.com -40 -40 +85 Revision 1.01 ºC In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may have to be derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP = 125ºC), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the part/package in the application (θJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (θJA × PD-MAX). 3 - 19 AS1332 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 TA = TJ = -40ºC to +85ºC; PVIN = VDD = EN = 3.6V, unless otherwise noted. Typ values are at TA = 25ºC. Table 3. Electrical Characteristics Symbol VFB,MIN VFB VFB,MAX 1 ISHDN 2 IQ Parameter Conditions Min Typ Max Units Feedback Voltage at Minimum Setting VCON = 0.4V 1.21 1.30 1.39 V Feedback Voltage VCON = 1.1V 2.693 2.75 2.807 V Feedback Voltage at Maximum Setting VCON = 1.4V 3.03 3.17 3.29 V Shutdown Supply Current EN = SW = VCON = 0V 0.01 2 µA DC Bias Current into VDD VCON = 1V, FB = 0V, No Switching 1 1.4 mA 1100 1200 mA 140 200 DC-DC Switches ILIM,PFET Switch Peak Current Limit RDSON(P) Pin-Pin Resistance for PFET RDSON(N) Pin-Pin Resistance for NFET Current limit is built-in, fixed, and not adjustable. 935 ISW = 200mA; TA = +25°C ISW = 200mA 230 ISW = -200mA; TA = +25°C 300 ISW = -200mA 415 485 mΩ mΩ Control Inputs VIH,EN Logic High Input Threshold VIL,EN Logic Low Input Threshold 1.2 IPIN,ENABLE Pin Pull Down Current V 0.5 V 5 7 µA VCON,min VCON Threshold Commanding VFB,MIN VCON swept down 0.484 0.52 0.556 V VCON,max VCON Threshold Commanding VFB,MAX VCON swept up 1.208 1.27 1.312 V ZCON VCON Input Resistance ICON Control Pin Leakage Current Gain VCON to VOUT Gain 3 TA = +25°C 100 kΩ -10 0.556V ≤ VCON ≤ 1.208V 10 2.5 µA V/V Oscillator FOSC Internal Oscillator Frequency 1.8 2 2.2 MHz 1. Shutdown current includes leakage current of PFET. 2. IQ specified here is when the part is operating at 100% duty cycle. 3. Derived by input leakage test. www.austriamicrosystems.com Revision 1.01 4 - 19 AS1332 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 System Characteristics TA = 25ºC; PVIN = VDD = EN = 3.6V, unless otherwise noted. The following parameters are verfied by characterisation and are not production tested. Table 4. System Characteristics Symbol Parameter Conditions Min Typ Max Unit s Control Inputs Time for VOUT to rise from 1.3V to 3.16V VIN = 4.2V, COUT = 4.7µF, L = 3.3µH, RLOAD = 5Ω 20 Time for VOUT to fall from 3.16V to 1.3V VIN = 4.2V, COUT = 4.7µF, L = 3.3µH, RLOAD = 10Ω 20 CCON VCON Input Capacitance VCON = 1V, Test frequency = 100 kHz Linearity Linearity in Control Range 0.556V to 1.208V VIN = 3.6V, Monotonic in nature TRESP T_ON Turn-On Time EN = Low to High, VIN = 4.2V, (time for output to reach 3.16V from VOUT = 3.16V, COUT = 4.7µF, IOUT ≤ 1mA enable low to high transition) 30 µs -3 210 30 20 pF +3 % 750 µs Performance Parameters η Efficiency (L = 3.3µH, DCR ≤ 100mΩ) VIN = 3.6V, VOUT = 1.3V, IOUT = 90mA 87 VIN = 3.6V, VOUT = 3.16V, IOUT = 400mA 96 VIN = 3V to 4.5V, VOUT = 1.3V, IOUT = 10mA to 400mA 10 mVp -p % VOUTripple Ripple voltage, PWM mode Line_tr Line transient response VIN = 600mV perturbance, over Vin range 3V to 5.5V; TRISE = TFALL = 10µs, VOUT = 1.3V, IOUT = 100mA 50 mVp k Load_tr Load transient response VIN = 3.1/3.6/4.5V, VOUT = 1.3V, transients up to 100mA, TRISE = TFALL = 10µs 50 mVp k PSRR VIN = 3.6V, VOUT = 1.3V, IOUT = 100mA sine wave perturbation frequency = 10kHz, amplitude = 100mVp-p 40 dB 1 1. Ripple voltage should measured at COUT electrode on good layout PC board and under condition using suggested inductors and capacitors. www.austriamicrosystems.com Revision 1.01 5 - 19 AS1332 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 Circuit in Figure 31 on page 12, PVIN = VDD = EN = 3.6V, L = 3.3µH (LPS4018-332ML_), CIN = 10µF (GRM21BR61C106KA01), COUT = 4.7µF (GRM32ER71H475KA88) unless otherwise noted; Figure 3. IQ vs. VIN; VCON = 2V, FB = 0V, no switching Figure 4. ISHDN vs. Temperature; VCON = 0V, EN = 0V 0.25 1.4 Vi n=2.7V Vi n=3.6V + 25°C 1.2 Shutdown Current (µA) . Quiescent Current (mA) - 45°C + 95°C 1 0.8 0.6 0.4 0.2 2.5 3 3.5 4 4.5 5 0.2 Vi n=4.2V Vi n=5.5V 0.15 0.1 0.05 0 -40 5.5 -15 Supply Voltage (V) Figure 5. Switching Frequency Variation vs. Temp. 35 60 85 Figure 6. VOUT vs. VIN; VOUT = 1.3V 4 1.39 3 1.36 2 Output Voltage (V) Switching Frequency Variation (%) 10 Temperature (°C) 1 0 -1 -2 Vi n=2.7V 1.33 1.3 1.27 Vi n=3.6V 1.24 Vi n=4.2V -3 Iout=50mA Iout=300mA Vi n=5.5V Iout=650mA -4 -40 1.21 -15 10 35 60 85 Temperature (°C) www.austriamicrosystems.com 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 Supply Voltage (V) Revision 1.01 6 - 19 AS1332 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 7. VOUT vs. Temp; VIN = 3.6V, VOUT = 1.3V Figure 8. VOUT vs. Temp; VIN = 3.6V, VOUT = 3.16V 1.35 3.2 Iout=50mA 1.34 Iout=650mA 1.32 1.31 1.3 1.29 1.28 3.16 3.15 3.14 3.13 3.12 1.26 3.11 -15 10 35 60 Iout=650mA 3.17 1.27 1.25 -40 Iout=300mA 3.18 Output Voltage (V) 1.33 Output Voltage (V) Iout=50mA 3.19 Iout=300mA 3.1 -40 85 -15 10 Temperature (°C) Figure 9. Switch Peak Current Limit vs. Temp. 60 85 Figure 10. VCON vs. VOUT; VIN = 4.2V, RLOAD = 8Ω 1.2 3.5 3 1.15 Output Voltage (V) Peak Current Limit (A) 35 Temperature (°C) 1.1 1.05 2.5 2 1.5 Vi n=2.7V - 45°C + 25°C Vi n=3.6V + 90°C Vi n=5.5V 1 -40 1 -15 10 35 60 85 0 0.5 1 1.5 2 VCON Voltage (V) Temperature (°C) Figure 11. Efficiency vs. VOUT; VIN = 3.6V Figure 12. Efficiency vs. IOUT; VOUT = 1.3V 100 100 Vi n=2.7V Vi n=3.25V 95 95 Vi n=3.6V Vi n=4.2V Efficiency (%) Efficiency (%) Vi n=5.5V 90 85 80 75 90 85 80 75 Rl oad=5Ohm Rl oad=10Ohm Rl oad=15Ohm 70 70 1 1.5 2 2.5 3 3.5 Output Voltage (V) www.austriamicrosystems.com 0 100 200 300 400 500 600 700 800 Output Current (mA) Revision 1.01 7 - 19 AS1332 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 13. Efficiency vs. IOUT; VOUT = 3.09V 100 Efficiency (%) 95 90 85 80 Vi n=2.7V Vi n=3.25V 75 Vi n=3.6V Vi n=4.2V Vi n=5.5V 70 0 100 200 300 400 500 600 700 800 Output Current (mA) 2V/Div 500mA/DIV 5V/Div 1V/Div 50µs/Div Revision 1.01 2V/Div 500mA/Div 50µs/Div www.austriamicrosystems.com 1V/Div VSW VOUT IL VSW VOUT IL 5V/Div 1V/Div EN IL EN 50µs/Div Figure 17. Shutdown Response; VIN = 4.2V, VOUT = 3.16V, COUT = 4.7µF, RLOAD = 10Ω 2V/Div 500mA/DIV VOUT VSW Figure 16. Startup; VIN = 4.2V, VOUT = 3.16V, IOUT<1mA, RLOAD = 4.7kΩ EN 50mA 250mA 200mA/Div VOUT IL IOUT 10µs/Div 5V/Div Figure 15. Startup; VIN = 3.6V, VOUT = 1.3V, IOUT<1mA, RLOAD = 4.7kΩ 50mV/Div Figure 14. Load Transient Response; VIN = 3.6V, VOUT = 1.3V 8 - 19 AS1332 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 VSW 3.16V 1.4V 1.3V VOUT 0V VCON 0V VCON 1.4V 1.3V VOUT 3.16V VSW 5V/Div Figure 19. VCON and Load Transient; VIN = 4.2V, VCON = 0V to 1.4V, 15Ω/8Ω, same time 5V/Div Figure 18. VCON Voltage Response; VIN = 4.2V, VCON = 0V to 1.4V, RLOAD = 10Ω 50µs/Div 50µs/Div 5V/Div 10mV/Div VSW VOUT IL 100mA/Div 5V/Div 1V/Div Figure 21. Output Voltage Ripple; VIN = 3.6V, VOUT = 1.3V, IOUT = 200mA 1A/Div IL VOUT VSW Figure 20. Timed Current Limit Response; VIN = 3.6V, VOUT = 1.3V, RLOAD = 10Ω 5µs/Div 200ns/Div Figure 22. VOUT Ripple in Skip Mode; VIN = 3.547V, VOUT = 3.16V, RLOAD = 5Ω Figure 23. RDSON (P-Chanel) vs. Temperature; ISW = 200mA 350 VOUT 20mV/Div 500ns/Div 250 RDSON (m Ω ) IL 500mA/Div VSW 2V/Div 300 200 150 100 Vi n=2.7V 50 Vi n=3.6V Vi n=5.5V 0 -40 -15 10 35 60 85 Temperature (°C) www.austriamicrosystems.com Revision 1.01 9 - 19 AS1332 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 24. RDSON (N-Chanel) vs. Temp.; ISW=-200mA Figure 25. EN High Threshold vs. VIN 350 1.2 EN High Threshold (V) 300 R DSON (m Ω ) 250 200 150 100 Vi n=2.7V 50 1.1 1 0.9 0.8 - 45°C Vi n=3.6V +25°C Vi n=5.5V 0 -40 +90°C 0.7 -15 10 35 60 85 2.7 3.1 3.5 Temperature (°C) Figure 26. VCON Threshold min vs. VIN 4.3 4.7 5.1 0.52 1.27 0.518 1.268 0.516 0.514 0.512 0.51 0.508 0.506 0.504 1.266 1.264 1.262 1.26 1.258 1.256 1.254 - 45°C 0.502 -45°C 1.252 +25°C +25°C +90°C +90°C 0.5 1.25 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 2.7 3.1 Supply Voltage (V) 3.5 3.9 4.3 4.7 5.1 5.5 Supply Voltage (V) Figure 28. VFB min vs. VIN; VCON = 0.4V, RLOAD = 10Ω Figure 29. VFB max vs. VIN; VCON = 0.4V, RLOAD=10Ω 3.2 1.39 1.36 3.18 1.33 VFB max (V) VFB min (V) 5.5 Figure 27. VCON Threshold max vs. VIN Vcon Threshold max (V) Vcon Threshold min (V) 3.9 Supply Voltage (V) 1.3 3.16 3.14 1.27 1.24 3.12 - 45°C - 45°C + 25°C + 25°C + 90°C + 90°C 1.21 3.1 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 Supply Voltage (V) www.austriamicrosystems.com 3 3.5 4 4.5 5 5.5 Supply Voltage (V) Revision 1.01 10 - 19 AS1332 Datasheet - D e t a i l e d D e s c r i p t i o n 8 Detailed Description For driving RF power amplifiers in portable devices and battery powered RF devices the AS1332 is a very suitable DCDC converter. The AS1332 features current overload protection, thermal overload shutdown and soft start. Besides these features the device also displays the following characteristics: ! Current-mode buck architecture with synchronous rectification for high efficiency. ! Operation at maximum efficiency over a wide range of power levels from a single Li-Ion battery cell. ! The maximum load capability of 650mA is provided in PWM mode, wherein the maximum load range may vary depending on input voltage, output voltage and the selected inductor. ! Efficiency is of around 96% for a 400mA load with 3.16V output and 3.6V input. ! For longer battery life, the output voltage can be dynamically programmable from 1.3V (typ) to 3.16V (typ) by adjusting the voltage on the control pin without the need for external feedback resistors. Figure 30. AS1332 Block Diagram VDD PVIN Oscillator Current Sense VCON PWM COMP Error Amplifier FB Mosfet Control Logic Clamp Logic and Soft Start SW Main Control EN Shutdown Control AS1332 AGND PGND AS1332 is fabricated using a 8-pin WL-CSP, which requires special design considerations for implementation. Its fine bumppitch requires careful board design and precision assembly equipment. This package offers the smallest possible size, for space-critical applications such as cell phones, where board area is an important design consideration. The size of the external components is reduced by using a high switching frequency (2MHz). For implementation only three external power components are required (see Figure 1 on page 1). The 8-pin WL-CSP package is appropriate for opaque case applications, where its edges are not subject to high intensity ambient red or infrared light. Also the system controller should set EN low during power-up and other low supply voltage conditions. See Shutdown Mode on page 13. www.austriamicrosystems.com Revision 1.01 11 - 19 AS1332 Datasheet - D e t a i l e d D e s c r i p t i o n Figure 31. Typical Operating System Circuit VIN 2.7V to 5.5V PVIN C1 10 µF VDD L1 3.3 µH VOUT 1.3V to 3.16V AS1332 VOUT = 2.5 x VCON FB C2 ON/OFF EN System Controller DAC VCON SW 4.7 µF AGND PGND Operating the AS1332 AS1332’s control block turns on the internal PFET (P-channel MOSFET) switch during the first part of each switching cycle, thus allowing current to flow from the input through the inductor to the output filter capacitor and load. The inductor limits the current to a ramp with a slope of around (VIN - VOUT) / L, by storing energy in a magnetic field. During the second part of each cycle, the controller turns the PFET switch off, blocking current flow from the input, and then turns the NFET (N-channel MOSFET) synchronous rectifier on. As a result, the inductor’s magnetic field collapses, generating a voltage that forces current from ground through the synchronous rectifier to the output filter capacitor and load. While the stored energy is transferred back into the circuit and depleted, the inductor current ramps down with a slope around VOUT / L. The output filter capacitor stores charge when the inductor current is high, and releases it when low, smoothing the voltage across the load. The output voltage is regulated by modulating the PFET switch on time to control the average current sent to the load. The effect is identical to sending a duty-cycle modulated rectangular wave formed by the switch and synchronous rectifier at SW to a low-pass filter formed by the inductor and output filter capacitor. The output voltage is equal to the average voltage at the SW pin. While in operation, the output voltage is regulated by switching at a constant frequency and then modulating the energy per cycle to control power to the load. Energy per cycle is set by modulating the PFET switch on-time pulse width to control the peak inductor current. This is done by comparing the signal from the current-sense amplifier with a slope compensated error signal from the voltage-feedback error amplifier. At the beginning of each cycle, the clock turns on the PFET switch, causing the inductor current to ramp up. When the current sense signal ramps past the error amplifier signal, the PWM comparator turns off the PFET switch and turns on the NFET synchronous rectifier, ending the first part of the cycle. If an increase in load pulls the output down, the error amplifier output increases, which allows the inductor current to ramp higher before the comparator turns off the PFET. This increases the average current sent to the output and adjusts for the increase in the load. Before appearing at the PWM comparator, a slope compensation ramp from the oscillator is subtracted from the error signal for stability of the current feedback loop. The minimum on time of PFET in PWM mode is 50ns (typ.) www.austriamicrosystems.com Revision 1.01 12 - 19 AS1332 Datasheet - D e t a i l e d D e s c r i p t i o n Internal Synchronous Rectifier To reduce the rectifier forward voltage drop and the associated power loss, the AS1332 uses an internal NFET as a synchronous rectifier. The big advantage of a synchronous rectification is the higher efficiency in a condition where the output voltage is low compared to the voltage drop across an ordinary rectifier diode. During the inductor current down slope in the second part of each cycle the synchronous rectifier is turned on. Before the next cycle the synchronous rectifier is turned off. There is no need for an external diode because the NFET is conducting through its intrinsic body diode during the transient intervals before it turns on. Dynamic Output Voltage Programming Because of the dynamically adjustable output voltage of the AS1332 there is no need for external feedback resistors. Through changing the voltage at the analog pin VCON, the output voltage is set from VFB,MIN to VFB,MAX. This is a very helpful feature because the supply voltage of a PA application can be changed due to the operation mode. For example, during the data transmission from a handset peak power is needed. In the other states the transmitting power can be reduced to ensure a longer battery lifetime. Shutdown Mode If EN is set to high (>1.2V) the AS1332 is in normal operation mode. During power-up and when the power supply is less than 2.7V minimum operating voltage, the chip should be turned off by setting EN low. In shutdown mode the following blocks of the AS1332 are turned off, PFET switch, NFET synchronous rectifier, reference voltage source, control and bias circuitry. The AS1332 is designed for compact portable applications, such as mobile phones where the system controller controls operation mode for maximizing battery life and requirements for small package size outweigh the additional size required for inclusion of UVLO (Under Voltage Lock-Out) circuitry. Note: Setting the EN digital pin low (<0.5V) places the AS1332 in a 0.01µA (typ.) shutdown mode. Thermal Overload Protection To prevent the AS1332 from short-term misuse and overload conditions the chip includes a thermal overload protection. To block the normal operation mode the device is turning the PFET and the NFET off in PWM mode as soon as the junction temperature exceeds 150°C. To resume the normal operation the temperature has to drop below 125°C. Note: Continuing operation in thermal overload conditions may damage the device and is considered bad practice. Current Limiting If in the PWM mode the cycle-by-cycle current limit of 1.2A (max.) is reached the current limit feature takes place and protects the device and the external components. A timed current limiting mode is working when a load pulls the output voltage down to approximately 0.375V. In this timed current limit mode the inductor current is forced to ramp down to a safe value. This is achieved by turning off the internal PFET switch and delaying the start of the next cycle for 3.5us. The synchronous rectifier is also turned off in the timed current limit mode. The advantage of the timed current limit mode is to prevent the device of the loss of the current control. www.austriamicrosystems.com Revision 1.01 13 - 19 AS1332 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 Through setting the voltage on the VCON pin (see Table 5) the output voltage of the AS1332 can be programmed from 1.3V (typ) to 3.16V (typ). This feature eliminates the need for external feedback resistors. If the voltage on the control pin varies from 0.556V to 1.208V, the output voltage will change according to the equation stated in Table 5. The output voltage is regulated at VFB,MIN as long as the voltage on the control pin is less than 0.484V. If the voltage on the control pin is higher than 1.312V, the output voltage is regulated at VFB,MAX. Before the control voltage is fed to the error amplifier inputs, the control voltage is clamped internal in the device. Table 5. Output Voltage Selection VCON (V) VOUT (V) VCON ≤ 0.484 VFB,MIN 0.556 < VCON < 1.208 VOUT = 2.5 x VCON VCON ≥ 1.312 VFB,MAX www.austriamicrosystems.com Revision 1.01 14 - 19 AS1332 Datasheet - A p p l i c a t i o n I n f o r m a t i o n External Component Selection Inductor Selection For the external inductor, a 3.3µH inductor is recommend. Minimum inductor size is dependant on the desired efficiency and output current. Inductors with low core losses and small DCR at 2MHz are recommended. Table 6. Recommended Inductors Part Number L DCR LPS4018-222ML_ 2.2µH 0.070Ω Current Rating Dimensions (L/W/T) 2.9A 3.9x3.9x1.7mm LPS4018-332ML_ 3.3µH 0.080Ω 2.4A 3.9x3.9x1.7mm LPS4018-472ML_ 4.7µH 0.125Ω 1.9A 3.9x3.9x1.7mm Manufacturer Coilcraft www.coilcraft.com Capacitor Selection A 10µF capacitor is recommend for CIN as well as a 4.7µF for COUT. Small-sized X5R or X7R ceramic capacitors are recommend as they retain capacitance over wide ranges of voltages and temperatures. Input and Output Capacitor Selection Low ESR input capacitors reduce input switching noise and reduce the peak current drawn from the battery. Also 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. For input decoupling the ceramic capacitor should be located as close to the device as practical. A 4.7µF input capacitor is sufficient for most applications. Larger values may be used without limitations. A 2.2µF to 10µF output ceramic 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. Table 7. Recommended Capacitors for the Step-Down Converter Part Number C Voltage Type Size GRM21BR60J226ME39 22µF 6.3V X5R 0805 GRM21BR60J106KE01 10µF 6.3V X5R 0805 GRM21BR61C475KA88 4.7µF 16V X5R 0805 GRM188R61C225KE15 2.2µF 16V X5R 0603 GRM188R61A225KE34 2.2µF 10V X5R 0603 C0603C475K8PAC7867 4.7µF 10V X5R 0603 Manufacturer Murata www.murata.com KEMET www.kemet.com EN Pin Control Drive the EN pin using the system controller to turn the AS1332 ON and OFF. Use a comparator, Schmidt trigger or logic gate to drive the EN pin. Set EN high (>1.2V) for normal operation and low (<0.5V) for a 0.01µA (typ.) shutdown mode. Set EN low to turn off the AS1332 during power-up and under voltage conditions when the power supply is less than the 2.7V minimum operating voltage. The part is out of regulation when the input voltage is less than 2.7V. www.austriamicrosystems.com Revision 1.01 15 - 19 AS1332 Datasheet - A p p l i c a t i o n I n f o r m a t i o n Layout Considerations The AS1332 converts higher input voltage to lower output voltage with high efficiency. This is achieved with an inductor based switching topology. During the first half of the switching cycle, the internal PMOS switch turns on, the input voltage is applied to the inductor, and the current flows from PVDD line to the output capacitor (C2) through the inductor. During the second half cycle, the PMOS turns off and the internal NMOS turns on. The inductor current continues to flow via the inductor from the device PGND line to the output capacitor (C2). Referring to Figure 32, the AS1332 has two major current loops where pulse and ripple current flow. The loop shown in the left hand side is most important, because pulse current shown in Figure 32 flows in this path. The right hand side is next. The current waveform in this path is triangular, as shown in Figure 32. Pulse current has many high-frequency components due to fast di/dt. Triangular ripple current also has wide high-frequency components. Board layout and circuit pattern design of these two loops are the key factors for reducing noise radiation and stable operation. Other lines, such as from battery to C1(+) and C2(+) to load, are almost DC current, so it is not necessary to take so much care. Only pattern width (current capability) and DCR drop considerations are needed. Figure 32. Current Loop VIN 2.7V to 5.5V i fOSC = 2MHz + C1 VDD PVIN i L1 - 10 µF 3.3 µH VOUT SW EN VOUT = 2.5 x VCON FB C2 4.7 µF VCON 0.52V to 1.27V www.austriamicrosystems.com VCON PGND Revision 1.01 + - AGND 16 - 19 AS1332 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 8-pin WL-CSP Figure 33. Package Drawings Top through view Bottom view (Ball side) 500 1 500 40 typ. 1 240 typ. 500 33 0± 20 CCC 500 1625 ±20µm 40 µm A A 40 µm 320 typ. 1515 ±20µm 600 ±30µm Notes: ccc Coplanarity All dimensions are in µm www.austriamicrosystems.com Revision 1.01 17 - 19 AS1332 Datasheet - O r d e r i n g I n f o r m a t i o n 11 Ordering Information The device is available as the standard products listed in Table 8. Table 8. Ordering Information Part Number AS1332-BWLT Marking ASQW Description 650mA, DC-DC Step-Down for RF Delivery Form Tape and Reel Package 8-pin WL-CSP All devices are RoHS compliant and free of halogene substances. www.austriamicrosystems.com Revision 1.01 18 - 19 AS1332 Datasheet Copyrights Copyright © 1997-2009, austriamicrosystems AG, Schloss Premstaetten, 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 austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. austriamicrosystems 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. austriamicrosystems 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 austriamicrosystems 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 austriamicrosystems 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 austriamicrosystems AG is believed to be correct and accurate. However, austriamicrosystems 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 austriamicrosystems AG rendering of technical or other services. Contact Information Headquarters austriamicrosystems AG Tobelbaderstrasse 30 A-8141 Unterpremstaetten - Graz, Austria Tel: +43 (0) 3136 500 0 Fax: +43 (0) 3136 525 01 For Sales Offices, Distributors and Representatives, please visit: http://www.austriamicrosystems.com/contact-us www.austriamicrosystems.com Revision 1.01 19 - 19