Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter General Description Features The AP3436/A is a step-down DC-DC converter with integrated power stage capable of driving up to 3A continuous output current. It integrates 2 N-channel power MOSFETs with low on-resistance. Current mode control provides fast transient response and cycle-by-cycle current limit. • • • • • • • • • • • • • For AP3436, the regulator adopts current-mode in forced pulse-width modulation (PWM) mode with 1.25MHz switching frequency internally, which allows small-sized components, such as capacitors and inductors. This feature greatly simplifies the design of switch-mode power supplies. Under PWM mode, the device remains at the fixed PWM operation (typical at 1.25MHz), regardless of if the load current is high or low. For AP3436A, the regulator operates in either fixed PWM mode or a pulse-skipping modulation (PSM) mode depending on the different load conditions. The device can operate at typical 1.25MHz fixed switching frequency under heavy load condition. At light load, the regulator enters a PSM mode to minimize the switching loss by reducing the switching frequency. AP3436/A Analog Power Input VCC Range: 3.0V to 5.5V Power Input VIN Range: 1.3V to 5.5V 0.6V Reference Voltage with ±1.5% Precision 2 MOSFETs (Typ 50mΩ) for High Efficiency at 3A Loads High Efficiency: Up to 95% Output Current: 3A Current Mode Control Built-in Soft Start Function UV and OV Power Good Output Built-in UV and OV Protection Function Built-in Over Current Protection Built-in Thermal Shutdown Function Thermally Enhanced 3mm×3mm DFN Package Applications • • • The AP3436/A provides EN function. Pulling this pin high statically enables the device while pulling the pin low statically for longer than 10µs will shut it down. Desktop & Notebook Low Voltage, High Density Power System Consumer Application Such as Set Top Box, LCD Display and CPE Equipment Under Voltage Lockout is internally set at 2.75V for VCC detection. The output voltage startup ramp is controlled by the soft start. An open drain power good signal indicates the output is within 75% to 125% of its nominal voltage. The AP3436/A is available in DFN-3×3-10 package. DFN-3×3-10 Figure 1. Package Type of AP3436/A Jan. 2013 Rev. 1.2 BCD Semiconductor Manufacturing Limited 1 Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter AP3436/A Pin Configuration DN Package (DFN-3×3-10) Pin 1 Mark 1 10 2 9 3 8 4 7 5 6 Figure 2. Pin Configuration of AP3436/A (Top View) Pin Description Pin Number Pin Name 1 FB 2 VCC Analog Power Input 3 VIN Power Input 4, 5 GND Ground. Must be Connected to GND on PCB 6, 7 SW 8 BOOT High Side Switch Driver Supply 9 PGOOD Open Drain Power Good Output 10 EN 11 Exposed Pad Jan. 2013 Function Voltage Feedback Input. Connect to VOUT through a voltage divider to set the output voltage Power Switch Output Enable Thermal Connection to the PCB. Must be connected to GND on PCB Rev. 1.2 BCD Semiconductor Manufacturing Limited 2 Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter AP3436/A Functional Block Diagram PGOOD EN 9 VCC 10 2 VIN 3 Thermal Shutdown UVLO 75% Logic EN 125% Boot Charge Shutdown Logic 8 BOOT Voltage Reference FB Boot UVLO 1 EA PWM + Soft Start Logic and PWM Latch 6,7 Slope Compensation SW Current Sense Current Limit and Short Protection Oscillator 4,5 4,5 GND GND Figure 3. Functional Block Diagram of AP3436/A Ordering Information AP3436 - G1: Green Circuit Type TR: Tape & Reel Blank: AP3436 A: AP3436A Package DN: DFN-3×3-10 Package Temperature Range DFN-3×3-10 -40 to 85°C Function PWM Part Number Marking ID AP3436DNTR-G1 BDB AP3436ADNTR-G1 BDF Packing Type Tape & Reel PWM/PSM BCD Semiconductor's Pb-free products, as designated with "G1" in the part number, are RoHS compliant and green. Jan. 2013 Rev. 1.2 BCD Semiconductor Manufacturing Limited 3 Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter AP3436/A Absolute Maximum Ratings (Note 1) Parameter Symbol Value Unit VCC, VIN Pin Voltage VCC, VIN -0.3 to 6 V EN Pin Voltage VEN V SW Pin Voltage VSW VSW_TRANSIENT -0.3 to 6 -0.3 to VIN+0.3 -5 to VIN+5 FB Pin Voltage VFB -0.3 to 6 V PGOOD Pin Voltage VPGD -0.3 to 6 V BOOT to SW Voltage VBOOT_SW 0 to 6 V Thermal Resistance (Junction to Ambient, Simulation) θJA 33 ºC/W Operating Junction Temperature TJ -40 to 150 ºC Storage Temperature TSTG -65 to 150 ºC Lead Temperature (Soldering, 10sec) TLEAD 260 ºC ESD (Human Body Model) VHBM 2000 V ESD (Machine Model) VMM 200 V SW Pin Transient Voltage (<50ns) V V Note 1: Stresses greater than those listed under “Absolute Maximum Ratings” 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 under “Recommended Operating Conditions” is not implied. Exposure to “Absolute Maximum Ratings” for extended periods may affect device reliability. Recommended Operating Conditions Parameter Symbol Min Max Unit Analog Input Voltage VCC 3.0 5.5 V Power Input Voltage VIN 1.3 5.5 V IOUT(MAX) 3 VOUT 0.8 VIN V TA -40 85 ºC Maximum Output Current Output Voltage Operating Ambient Temperature Jan. 2013 Rev. 1.2 A BCD Semiconductor Manufacturing Limited 4 Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter AP3436/A Electrical Characteristics VCC=5V, VIN=5V, TA=25°C, unless otherwise specified. Parameter Symbol Conditions SUPPLY VOLTAGE (VCC, VIN PIN) Analog Power Input VCC Voltage VIN Power Input Voltage IQ Quiescent Current Shutdown Supply Current ISHDN Min Typ Max Unit 3.0 5.5 V 1.3 5.5 V VFB=1.5V, VCC=5V, VIN=5V VEN=0V, 3.0V≤VCC≤5.5V, 1.3V≤VIN≤5.5V POWER ON RESET Internal Under Voltage VUVLO Lockout Threshold for VCC Internal Under Voltage VHYS_VCC Hysteresis for VCC VOLTAGE REFERENCE (FB PIN) VFB Voltage Reference µA 400 2.75 1 µA 2.85 V 150 mV 3.0V≤VCC≤5.5V 0.591 0.600 0.609 V 3.0V≤VCC≤5.5V 1.0 1.25 1.5 MHz VBOOT_SW=5.0V 50 100 mΩ VBOOT_SW=3.0V 70 140 mΩ VCC=5.0V 50 100 mΩ VCC=3.0V 70 140 mΩ INTERNAL PWM FREQUENCY f PWM Frequency MOSFET SPEC High Side On-resistance Switch Low Side On-resistance Switch RON_H RON_L CURRENT LIMIT Current Limit Threshold ILIMIT 4.8 7.6 A 160 °C 20 °C VCC=5.0V 16 Ω VCC=3.0V 2.2 V THERMAL SHUTDOWN Thermal Shutdown TTSD Hysteresis BOOT SPEC (BOOT PIN) BOOT Charge Resistor RBOOT BOOT to SW UVLO SOFT START Soft Start Time Jan. 2013 tSS 0.8 Rev. 1.2 2 ms BCD Semiconductor Manufacturing Limited 5 Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter AP3436/A Electrical Characteristics (Continued) VCC=5V, VIN=5V, TA=25°C, unless otherwise specified. Parameter Symbol Conditions Min Typ Max Unit 0.8 V ENABLE (EN PIN) EN Pin Threshold VEN_L VEN_H 1.6 V POWER GOOD (PGOOD PIN) Feedback Threshold VFBTH Delay Time for PGOOD from High to tPG_DLY Low Internal Power Good RPG Pull Low Resistance External Pull-up RPG_UP Resistance Range SYSTEM PERFORMANCE Output Under Voltage VUVP Protection Threshold Delay Time for UVP tUVP Triggered Output Over Voltage VOVP Protection Threshold Delay Time for OVP tOVP Triggered Output Current Output Voltage Line Regulation Output Voltage Load Regulation Output Voltage Load Transient Efficiency Jan. 2013 IOUT VFB falling (Fault) 70 75 VFB rising (Good) 77 82 VFB rising (Fault) 125 130 VFB falling (Good) 118 123 150 η 0.5× VOUT VIN=1.3 to 5.5V VIN=1.3 to 5.5V 65 1.5× VOUT VIN=1.5 to 5V VIN=1.5 to 5V, VOUT=1.0V VIN=1.5 to 5V, IOUT=100mA VIN=5V, VOUT=1.0V, dI/dt=400mA/µs VCC=5V, VIN=5V, IOUT=3A, VOUT=1.2V Rev. 1.2 Ω Ω 3000 IOUT=0A to 3A VTRAN µs 30 VIN=1.5 to 5V %VREF V µs V 65 3 µs A 0.4 0.3 ±2.5 80 %× VOUT/V %× VOUT/A %× VOUT/A % BCD Semiconductor Manufacturing Limited 6 Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter AP3436/A Typical Performance Characteristics 0.608 80 0.606 70 0.604 Reference Voltage(V) 0.610 90 Efficiency (%) 100 60 50 40 30 AP3436 20 0.600 0.598 0.596 0.594 VIN=VCC=5.0V 10 0.602 0.592 VOUT=1.0V VIN=VCC=VEN 0.590 3.00 0 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 Output Current (A) 4.25 4.50 4.75 5.00 5.25 5.50 Input Voltage(V) Figure 4. Efficiency vs. Output Current Figure 5. Reference Voltage vs. Input Voltage 1.50 0.64 1.45 0.63 VIN=VCC=5.0V 1.40 PWM Frequency (MHz) 0.62 Reference Voltage(V) 4.00 0.61 0.60 0.59 0.58 1.35 1.30 1.25 1.20 1.15 1.10 0.57 1.05 0.56 -40 1.00 3.00 -20 0 20 40 60 80 100 120 140 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50 Input Voltage (V) o Temperature ( C) Figure 6. Reference Voltage vs. Temperature Jan. 2013 VCC=VIN=VEN Figure 7. PWM Frequency vs. Input Voltage Rev. 1.2 BCD Semiconductor Manufacturing Limited 7 Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter AP3436/A Typical Performance Characteristics (Continued) 1.50 10.0 1.45 9.5 VIN=VCC=5.0V 9.0 8.5 1.35 Current Limit (A) PWM Frequency (MHz) 1.40 1.30 1.25 1.20 1.15 8.0 7.5 7.0 6.5 1.10 6.0 1.05 5.5 1.00 -40 -20 0 20 40 60 80 100 120 5.0 3.00 140 VIN=VCC=VEN 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50 Input Voltage (V) o Temperature ( C) Figure 8. PWM Frequency vs. Temperature Figure 9. Current Limit vs. Input Voltage 9.00 0.4 8.75 0.3 8.50 VIN=VCC=5.0V 0.2 Line Regulation (%) Current Limit (A) 8.25 8.00 7.75 7.50 7.25 7.00 6.75 0.1 0.0 -0.1 -0.2 VIN= VCC= VEN 6.50 -0.3 6.25 6.00 -40 VOUT = 1.0V -20 0 20 40 60 80 100 120 -0.4 3.00 140 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50 Input Voltage (V) o Temperature ( C) Figure 10. Current Limit vs. Temperature Jan. 2013 3.25 Figure 11. Line Regulation vs. Input Voltage Rev. 1.2 BCD Semiconductor Manufacturing Limited 8 Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter AP3436/A Typical Performance Characteristics (Continued) 1.0 0.8 Load Regulation (%) 0.6 VIN 2V/div VOUT 500mV/div 0.4 0.2 0.0 -0.2 -0.4 -0.6 IL 1A/div VIN=VCC=VEN=5.0V -0.8 VOUT=1.0V -1.0 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 Time 400µs/div Output Current (A) Figure 12. Load Regulation vs. Output Current Figure 13. Power on Waveform (VIN=VCC=5V, VOUT=1V, IOUT=3A) VIN 2V/div VCC/IN 2V/div VEN 1V/div VOUT 1V/div VOUT 500mV/div IL 2A/div Jan. 2013 IL 1A/div Time 20ms/div Time 1ms/div Figure 14. Power off Waveform (VIN=VCC=5V, VOUT=1V, IOUT=3A) Figure 15. Enable Waveform (VIN=VCC=5V, VOUT=1V, IOUT=3A) Rev. 1.2 BCD Semiconductor Manufacturing Limited 9 Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter AP3436/A Typical Performance Characteristics (Continued) VCC/IN 2V/div VEN 1V/div VOUT 500mV/div IL 1A/div VOUT_AC 20mV/div IOUT 1A/div Time 200µs/div Time 200µs/div Figure 16. Disable Waveform (VIN=VCC=5V, VOUT=1V, IOUT=3A) Figure 17. Load Transient Response (VIN=VCC=5V, VOUT=1V, IOUT=0 to 3A) VOUT_AC 20mV/div IOUT 1A/div Time 200µs/div Figure 18. Load Transient Response (VIN=VCC=3.3V, VOUT=1V, IOUT=0 to 3A) Jan. 2013 Rev. 1.2 BCD Semiconductor Manufacturing Limited 10 Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter AP3436/A Typical Application VCC VIN VOUT CVCC CIN RPG 9 PGOOD VIN 1 L1 CBOOT 10 EN 2 3 BOOT 8 SW SW GND GND EP VCC FB 6 7 4 5 11 COUT RFB2 RFB1 Note 2: When using a single power supply for VCC and VIN, a 4.7Ω resistor should be placed between them for noise isolation. Figure 19. Typical Application Circuit of AP3436/A Table 1. Component Guide Jan. 2013 Component CVCC Value 1 Unit Value 44 Unit µF Component CIN RPG 10 kΩ CBOOT 0.1 µF RFB2 TBD kΩ L1 1.5 µH RFB1 TBD kΩ COUT 88 µF Rev. 1.2 µF BCD Semiconductor Manufacturing Limited 11 Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter Application Information R2 = 1. Overview The AP3436/A is a 3A synchronous buck (step-down) converter with two integrated N-channel MOSFETs. For AP3436, the regulator operates in PWM mode with 1.25MHz switching frequency internally, regardless of if the load current is high or low. For AP3436A, when the load is very light, the regulator automatically operates in the PSM mode to minimize the switching loss, thus achieving high efficiency at light load. When the load increases, the regulator automatically switches over to a current-mode PWM operating at nominal 1.25MHz switching frequency. R1 × 0.6 VOUT − 0.6 VOUT AP3436/A R1 FB R2 0.6V VSS + + Figure 20. Voltage Divider Circuit 2. Power On Reset A Power On Reset (POR) circuitry continuously monitors the supply voltage at VCC pin. Once the rising POR threshold is exceeded, the AP3436/A sets itself to active state and is ready to accept chip enable command. The rising POR threshold is typically 2.75V. 6. Short Circuit Protection (SCP) The AP3436/A has Over Current Protection (OCP) and Under Voltage Protection (UVP) functions. 6.1 OCP Function The high side switch current is detected during each cycle. During SCP conditions, the output voltage is pulled down and the switch current is increased. Once the increased high side switching current is detected to trigger the current limit of high side switch, the high side switch will be immediately turned off and will not be turned on again until the next switching cycle. When over current condition is removed, the AP3436/A will recover back to normal operation again. 3. Soft Start A built-in soft-start is used to prevent surge current from power supply input VIN during turn on (Referring to the Functional Block Diagram). The error amplifier is a three-input device. Reference voltage VREF or the internal soft-start voltage VSS whichever is smaller dominates the behavior of the non-inverting inputs of the error amplifier. VSS internally ramps up to 0.6V after the soft-start cycle is initiated. The ramp is created digitally, so the output voltage will follow the VSS signal and ramps up smoothly to its target level. 6.2 UVP Function The FB voltage is also monitored for Under Voltage Protection. The UV threshold is set at 0.2V. The under voltage protection has 65µs triggered delay. When UVP is triggered, both high side and low side are shutdown immediately. The UVP is a latched function, reset power supply or EN pin to restart AP3436/A again. 4. EN Function The AP3436/A provides Enable Function. Pulling this pin higher than 1.6V statically enables the AP3436/A while pulling the pin lower than 0.8V statically for longer than 10µs will shutdown the IC. 7. Over Voltage Protection (OVP) 5. Adjusting Output Voltage The output voltage is continuously monitored for Over Voltage Protection by FB pin. When it is larger than 1.67 times as setting, the OVP function is triggered. The Over Voltage Protection has 65µs triggered delay. The output voltage is set with a resistor divider from the FB pin. It is recommended to use divider resistors with 1% tolerance or better. Start with a 100kΩ for the resistor R1 and use the following equation to calculate R2. Consider using larger value resistors to improve efficiency at very light loads. If the values are too high, the regulator is more susceptible to noise and the voltage errors caused by FB input current are noticeable. Jan. 2013 AP3436/A When OVP is triggered, both high side and low side are shutdown immediately and the output voltage is discharged by an internal 1kΩ resistor. Rev. 1.2 BCD Semiconductor Manufacturing Limited 12 Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter AP3436/A Application Information (Continued) 100kΩ to a voltage source that is 5V or less. 8. Power Good The PGOOD pin output connects an open drain MOSFET. The output is pulled low when the FB voltage enters the fault condition by falling below 75% or rising above 125% of the nominal internal reference voltage. There is a 7% hysteresis on the threshold voltage, so when the FB voltage rises to the good condition above 82% or falls below 118% of the internal voltage reference the PGOOD output MOSFET is turned off. It is recommended to use a pull-up resistor between the values of 3kΩ and Jan. 2013 9. Thermal Shutdown The device implements an internal thermal shutdown to protect itself if the junction temperature exceeds 160°C. Switching is stopped when the junction temperature exceeds the thermal trip threshold. Once the die temperature decreases below 140°C, the device reinitiates the soft start operation. The thermal shutdown hysteresis is 20°C. Rev. 1.2 BCD Semiconductor Manufacturing Limited 13 Data Sheet 3A, 1.25MHz High Performance Synchronous Buck Converter AP3436/A Mechanical Dimensions DFN-3×3-10 Unit: mm(inch) 1.600(0. 063) 0.300(0. 012) 1.800(0. 071) 0.500(0. 020) 0.500(0. 020) 2.900(0. 114) TYP 3.100(0.122) N6 N10 2.300(0. 090) 2.500(0. 098) 2.900(0. 114) PIN #1 IDENTIFICATION See DETAIL A 3.100(0. 122) Pin 1 Mark N5 N1 0.200(0. 008) 0.700(0.028) 0.800(0. 031) 0.000(0. 000) 0.300(0. 012) DETAIL A 0.050(0. 002) 0.153(0. 006) 0.253(0. 010) 2 1 2 1 2 1 Pin 1 options Jan. 2013 Rev. 1.2 BCD Semiconductor Manufacturing Limited 14 BCD Semiconductor Manufacturing Limited http://www.bcdsemi.com IMPORTANT NOTICE IMPORTANT NOTICE BCD Semiconductor BCD Semiconductor Manufacturing Manufacturing Limited Limited reserves reserves the the right right to to make make changes changes without without further further notice notice to to any any products products or or specifispecifications herein. cations herein. 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