ACT4501 | DigiCamel IC Datasheet

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ACT4501 ACTIVE-SEMI | Alldatasheet

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Manufacturer or author: Provided By alldatasheet.com(free datasheet download site)
PDF pages: 15

Technical content

FEATURES

10V-30V Input Voltage
40V Transparent Input Voltage Surge
Up to 1.25A Constant Output Current
Output Voltage up to 12V
Good EMC Performance on Single Layer PCB
Patent Pending ActiveCC Constant Current Control − Integrated Current Control Improves Efficiency, Lowers Cost, and Reduces Component Count
Resistor Programmable Outputs − Current Limit from 500mA to 1250mA Patented cable compensation from DC Cable Compensation from 0Ω to 0.5Ω
2% Feedback Voltage Accuracy
Up to 90% Efficiency
125kHz Switching Frequency Eases EMI Design
Advanced Feature Set − Integrated Soft Start − Thermal Shutdown − Secondary Cycle-by-Cycle Current Limit − Protection Against Shorted ISET Pin
SOP-8 Package

APPLICATIONS

Car Charger
Rechargeable Portable Devices
General-Purpose CC/CV Power Supply GENERAL DESCRIPTION ACT4501 is a dedicated cost-effective DC-DC converter for 5V/1A car charger applications with a wide input voltage and high efficiency. The converter operates in either CV (Constant Output Voltage) mode or CC (Constant Output Current) mode. ACT4501 provides up to 1.25A output current at 125kHz switching frequency. ActiveCC is a patent-pending control scheme to achieve high accuracy sensorless constant current control. ActiveCC eliminates the expensive, high accuracy current sense resistor, making it ideal for battery charging applications and high-brightness LED drive for architectural lighting. The ACT4501 achieves higher efficiency than traditional constant current switching regulators by eliminating the sense resistor and its associated power loss. Protection features include cycle-by-cycle current limit, thermal shutdown, and frequency foldback at short circuit. The devices are available in a SOP-8 package and require very few external devices for operation. ACT4501 1.25A CC/CV Step-Down DC/DC Converter Rev 2, 14-Nov-12 Efficiency (%) ACT4501-001 Load Current (mA) 10 100 1000 10000 1 100 Efficiency vs. Load Current VIN = 12V VOUT = 5V VIN = 24V VIN = 16V

ORDERING INFORMATION

PART NUMBER TEMPERATURE RANGE PACKAGE PINS PACKING ACT4501SH-T -40°C to 85°C SOP-8 8 TAPE & REEL PIN CONFIGURATION PIN DESCRIPTIONS PIN NAME DESCRIPTION 1 HSB High Voltage Bias Pin. This provides power to the internal high-side MOSFET gate driver. Connect a 10nF capacitor from HSB pin to SW pin. 2 IN Power Supply Input. Bypass this pin with a 10µF ceramic capacitor to GND, placed as close to the IC as possible. 3 SW Power Switching Output to External Inductor.

4 GND

Ground. Connect this pin to a large PCB copper area for best heat dissipation. Return FB, COMP, and ISET to this GND, and connect this GND to power GND at a single point for best noise immunity. 5 FB Feedback Input. The voltage at this pin is regulated to 0.808V. Connect to the resistor divider between output and GND to set the output voltage. 6 COMP Error Amplifier Output. This pi n is used to compensate the converter. 7 EN Enable Input. EN is pulled up to 5V with a 4μA current, and contains a precise 0.8V logic threshold. Drive this pin to a logic-high or leave unconnected to enable the IC. Drive to a logic-low to disable the IC and enter shutdown mode. 8 ISET Output Current Setting Pin. Connect a resistor from ISET to GND to program the output current. SOP-8

Rev 2, 14-Nov-12 Innovative PowerTM - 3 - www.active-semi.com Copyright © 2012 Active-Semi, Inc. ABSOLUTE MAXIMUM RATINGSc PARAMETER VALUE UNIT IN to GND -0.3 to 40 V SW to GND -1 to VIN + 1 V HSB to GND VSW - 0.3 to VSW + 7 V FB, EN, ISET, COMP to GND -0.3 to + 6 V Junction to Ambient Thermal Resistance 105 °C/W Operating Junction Temperature -40 to 150 °C Storage Junction Temperature -55 to 150 °C Lead Temperature (Soldering 10 sec.) 300 °C c: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rati ng conditions for long periods m ay affect device reliability.

Rev 2, 14-Nov-12 Innovative PowerTM - 4 - www.active-semi.com Copyright © 2012 Active-Semi, Inc. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT Input Voltage 10 30 V VIN UVLO Turn-On Voltage Input Vo ltage Rising 9.05 9.35 9.65 V VIN UVLO Hysteresis Input Voltage Falling 1.1 V Standby Supply Current VEN = 3V, VFB = 1V 1.0 mA VEN = 3V, VO = 5V, No load 2.5 mA Shutdown Supply Current V EN = 0V 75 100 µA Feedback Voltage 792 808 824 mV Internal Soft-Start Time 800 µs Error Amplifier Transconductance V FB = VCOMP = 0.8V, ∆ICOMP = ± 10µA 650 µA/V Error Amplifier DC Gain 4000 V/V Switching Frequency V FB = 0.808V 115 125 130 kHz Foldback Switching Frequency V FB = 0V 10 16 38 kHz Maximum Duty Cycle 85 88 93 % Minimum On-Time 800 ns COMP to Current Limit Transconductance V COMP = 1.2V 1.75 A/V Switch Current Limit Duty = 50% 1.8 A Slope Compensation Duty = D MAX 0.75 A ISET Voltage 1 V ISET to IOUT DC Room Temp Current Gain IOUT / ISET 25000 A/A EN Threshold Voltage EN Pin Rising 0.75 0.8 0.85 V EN Hysteresis EN Pin Falling 80 mV EN Internal Pull-up Current 4 µA High-Side Switch ON-Resistance 0.3 Ω SW Off Leakage Current V EN = VSW = 0V 1 10 µA Thermal Shutdown Temperature Temperature Rising 155 °C CC Controller DC Accuracy R ISET = 19.6kΩ, VIN = 10V - 30V 1020 1200 1380 mA

ELECTRICAL CHARACTERISTICS

(VIN = 14V, TA = 25°C, unless otherwise specified.)

Rev 2, 14-Nov-12 Innovative PowerTM - 5 - www.active-semi.com Copyright © 2012 Active-Semi, Inc. FUNCTIONAL BLOCK DIAGRAM FUNCTIONAL DESCRIPTION CV/CC Loop Regulation As seen in Functional Block Diagram, the ACT4501 is a peak current mode pulse width modulation (PWM) converter with CC and CV control. The converter operates as follows: A switching cycle starts when the rising edge of the Oscillator clock output ca uses the High-Side Power Switch to turn on and the Low-Side Power Switch to turn off. With the SW side of the inductor now connected to IN, the inductor current ramps up to store energy in the magnetic field. The inductor current level is measured by the Current Sense Amplifier and added to the Oscillator ramp signal. If the resulting summation is higher than the COMP voltage, the output of the PWM Comparator goes high. When this happens or when Oscillator clock output goes low, the High-Side Power Switch turns off. At this point, the SW side of the inductor swings to a diode voltage below ground, causing the inductor current to decrease and magnetic energy to be transferred to output. This state continues until the cycle starts again. The High-Side Power Switch is driven by logic using HSB as the positive rail. This pin is charged to V SW + 5V when the Low-Side Power Switch turns on. The COMP voltage is the integration of the error between FB input and the internal 0.808V reference. If FB is lower than the reference voltage, COMP tends to go higher to increase current to the ou tput. Output current will increase until it reaches the CC limit set by the ISET resistor. At this point, t he device will transition from regulating output voltage to regulating output current, and the output voltage will drop with increasing load. The Oscillator normally switches at 125kHz. However, if FB voltage is less than 0.6V, then the switching frequency decreases until it reaches a typical value of 20kHz at V FB = 0.15V. Enable Pin The ACT4501 has an enable input EN for turning the IC on or off. The EN pin contains a precision 0.8V comparator with 75mV hysteresis and a 4µA pull-up current source. The comparator can be used with a resistor divider from V IN to program a startup voltage higher than the normal UVLO value. It can be used with a resistor divider from V OUT to disable charging of a deeply discharged battery, or it can be used with a resistor divider containing a thermistor to provide a temperature-dependent shutoff protection for over temperature battery. The thermistor should be thermally coupled to the battery pack for this usage. If left floating, the EN pin will be pulled up to roughly 5V by the internal 4µA current source. It can be driven from standard logic signals greater than 0.8V, or driven with open-drain logic to provide digital on/off control. Thermal Shutdown The ACT4501 disables switching when its junction temperature exceeds 155°C and resumes when the temperature has dropped by 20°C. EN FB BANDGAP, REGULATOR, SHUTDOWN CONTROL OSCILLATOR VREF = 0.808V EMI CONTROL PWM CONTROLLER CC CONTROL SW HSB IN AVIN PVIN COMP ISET VREF = 0.808V

Rev 2, 14-Nov-12 Innovative PowerTM - 7 - www.active-semi.com Copyright © 2012 Active-Semi, Inc. (6) ESRRIPPLEOUTMAXRIPPLE RKIV = OUT SW IN LCf28 V APPLICATIONS INFORMATION CONT’D Figure 3: External High Voltage Bias Diode This diode is also recommended for high duty cycle operation and high output voltage applications. Input Capacitor The input capacitor needs to be carefully selected to maintain sufficiently low ripple at the supply input of the converter. A low ESR capacitor is highly recommended. Since large current flows in and out of this capacitor during switching, its ESR also affects efficiency. The input capacitance needs to be higher than 10µF. The best choice is the ceramic type, however, low ESR tantalum or electrolytic types may also be used provided that the RMS ripple current rating is higher than 50% of the output current. The input capacitor should be placed close to the IN and G pins of the IC, with the shortest traces possible. In the case of tantalum or electrolytic types, they can be further away if a small parallel 0.1µF ceramic capacitor is placed right next to the IC. Output Capacitor The output capacitor also needs to have low ESR to keep low output voltage ripple. The output ripple voltage is: where IOUTMAX is the maximum output current, KRIPPLE is the ripple factor, R ESR is the ESR of the output capacitor, fSW is the switching frequency, L is the inductor value, and C OUT is the output capacitance. In the case of ceramic output capacitors, RESR is very small and does not contribute to the ripple. Therefore, a lower capacitance value can be used for ceramic type. In the case of tantalum or electrolytic capacitors, the ripple is dominated by R ESR multiplied by the ripple current. In that case, the output capacitor is chosen to have sufficiently low ESR. For ceramic output capacitor, typically choose a capacitance of about 22µF. For tantalum or electrolytic capacitors, choose a capacitor with less than 50mΩ ESR. Rectifier Diode Use a Schottky diode as the rectifier to conduct current when the High-Side Power Switch is off. The Schottky diode must have current rating higher than the maximum output current and a reverse voltage rating higher than the maximum input voltage.

Rev 2, 14-Nov-12 Innovative PowerTM - 8 - www.active-semi.com Copyright © 2012 Active-Semi, Inc. VOUT C OUT R COMP C COMP C COMP2 c 2.5V 47 μF SP CAP 25k Ω 1.5nF None 3.3V 47 μF SP CAP 25k Ω 1.8nF None 5V 47 μF SP CAP 25k Ω 2.2nF None 2.5V 220 μF/6.3V/30mΩ 25k Ω 1.5nF 100pF 3.3V 220 μF/6.3V/30mΩ 25k Ω 1.8nF 100pF 5V 220 μF/6.3V/30mΩ 25k Ω 2.2nF 100pF ⎛ ××≥ OUT OUT ESRCOUT V012.0,C 101.1MinR (15) (Ω) (16) COMP ESRCOUTOUT 2COMP R RCC = OUTOUT COMP CV102.1C −×= (F) (14) (13) (F) COMP COMP R 108.1C −×= (12) (Ω) OUTOUT 8 CV1075.2 ×= V808.0GG10 fCV2R COMPEA SWOUTOUT COMP ×= π (11) COMP2COMP 3P CRπ2 1f = (10) COMP2COMP CRπ2 1f = (9) OUTOUT OUT CVπ2 If = (8) COMPVEA EA CAπ2 Gf = (7) COMPVEA OUT VDC GAI V808.0A = STABILITY COMPENSATION Figure 4: Stability Compensation c: CCOMP2 is needed only for high ESR output capacitor The feedback loop of the IC is stabilized by the components at the COMP pin, as shown in Figure 3. The DC loop gain of the system is determined by the following equation: The dominant pole P1 is due to C COMP: The second pole P2 is the output pole: The first zero Z1 is due to R COMP and CCOMP: And finally, the third pole is due to R COMP and CCOMP2 (if CCOMP2 is used): The following steps should be used to compensate the IC: STEP 1. Set the cross over frequency at 1/10 of the switching frequency via R COMP: STEP 2. Set the zero f Z1 at 1/4 of the cross over frequency. If RCOMP is less than 15k Ω, the equation for CCOMP is: If R COMP is limited to 15k Ω, then the actual cross over frequency is 3.4 / (VOUTCOUT). Therefore: STEP 3. If the output capacitor’s ESR is high enough to cause a zero at lower than 4 times the cross over frequency, an additional compensation capacitor C COMP2 is required. The condition for using CCOMP2 is: And the proper value for C COMP2 is: Though C COMP2 is unnecessary when the output capacitor has sufficiently low ESR, a small value CCOMP2 such as 100pF may improve stability against PCB layout parasitic effects. Table 2 shows some calculated results based on the compensation method above. Table 1: Typical Compensation for Different Output Voltages and Output Capacitors c: CCOMP2 is needed for high ESR output capacitor. CCOMP2 ≤ 47pF is recommended. CC Loop Stability The constant-current control loop is internally compensated over the 400mA-1500mA output range. No additional external compensation is required to stabilize the CC current. Output Cable Resistance Compensation To compensate for resistive voltage drop across the charger's output cable, the ACT4501 integrates a simple, user-programmable cable voltage drop compensation using the impedance at the FB pin. Use the curve in Figure 4 to choose the proper

Rev 2, 14-Nov-12 Innovative PowerTM - 10 - www.active-semi.com Copyright © 2012 Active-Semi, Inc. Figure 8: Typical Application Circuit for 5V/1A Car Charger Table 2: BOM List for 5V/1A Car Charger ITEM REFERENCE DESCRIPTION MANUFACTURER QTY

1 U1 IC, ACT4501SH, SOP-8 Active-Semi 1

2 C1 Capacitor, Electrolytic, 47µF/50V, 6.3 х7mm Murata, TDK 1 3 C2 Capacitor, Ceramic, 2.2µF/50V, 1206, SMD Murata, TDK 1 4 C3 Capacitor, Ceramic, 2.2nF/6.3V, 0603, SMD Murata, TDK 1

5 C4 Capacitor, Ceramic, 10nF/50V, 0603, SMD Murata, TDK 1

6 C5 Capacitor, Electrolytic, 100µF/10V, 6.3 х7mm Murata, TDK 1 9 L1 82µH, 1.4A, 20%, SMD CDRH125-820M Sumida 1

10 D1 Diode, Schottky, 40V/2A, B240A, SMA Diodes 1

12 R1 Chip Resistor, 20k Ω, 0603, 1% Murata, TDK 1

13 R2 Chip Resistor, 52k Ω, 0603, 1% Murata, TDK 1

14 R3 Chip Resistor, 25k Ω, 0603, 5% Murata, TDK 1

15 R4 Chip Resistor, 10k Ω, 0603, 1% Murata, TDK 1

11 D2 Diode, 75V/150mA, LL4148 Good-ARK 1

7 C6 Capacitor, Ceramic, 1µF/10V, 0603, SMD Murata, TDK 1

8 C7 (Optional) Capacitor, Ceramic, 100pF/6.3V, 0603 Murata, TDK 1

Rev 2, 14-Nov-12 Innovative PowerTM - 11 - www.active-semi.com Copyright © 2012 Active-Semi, Inc. TYPICAL PERFORMANCE CHARACTERISTICS Input Voltage (V) 5 10 15 20 25 30 35 ACT4501-005 Switching Frequency vs. Input Voltage Switching Frequency (kHz) 125 120 115 110 105 100 130 ACT4501-006 Switching Frequency vs. Feedback Voltage Switching Frequency (kHz) 100 120 140 Feedback Voltage (V) 0 0.2 0.4 0.6 0.8 1 ACT4501-007 1000 900 800 700 600 500 400 CC Current (mA) Temperature (°C) -40 -25 0 25 50 75 80 ACT4501-008 CC Current vs. Input Voltage CC Current (mA) 1000 900 800 700 600 500 400 ACT4501-009 Peak Current Limit vs. Duty Cycle Maximum CC Current (mA) 2500 2250 2000 1750 1500 1250 1000 750 500 250 Duty Cycle CC Current vs. Temperature Input Voltage (V) 10 12 18 24 30 VIN = 12V RISET = 33kΩ RISET = 33kΩ (Circuit of Figure 7, IISET = 1A, L = 82µH, CIN = 10µF, COUT = 22µF, TA = 25°C, unless otherwise specified.) Efficiency (%) ACT4501-004 Load Current (mA) 10 100 1000 10000 1 100 Efficiency vs. Load Current VIN = 12V VOUT = 5V VIN = 24V VIN = 16V

Rev 2, 14-Nov-12 Innovative PowerTM - 12 - www.active-semi.com Copyright © 2012 Active-Semi, Inc. TYPICAL PERFORMANCE CHARACTERISTICS CONT’D ACT4501-011 Standby Supply Current vs. Input Voltage Input Current (mA) ACT4501-012 Reverse Leakage Current (VIN Floating) Reverse Leakage Current (µA) 100 VOUT (V) Input Voltage (V) 5 15 25 35 SW vs. Output Voltage Ripples ACT4501-013 VIN = 12V V0UT = 5V I0UT = 1A CH1 CH2 CH1: VOUT, 50mV/div CH2: VSW, 5V/div TIME: 4µs/div (Circuit of Figure 7, IISET = 1A, L = 82µH, CIN = 10µF, COUT = 22µF, TA = 25°C, unless otherwise specified.) Shutdown Current vs. Input Voltage (EN pulled low) ACT4501-010 140 120 100 Shutdown Current (µA) Input Voltage (V) 5 10 15 20 25 30 SW vs. Output Voltage Ripples ACT4501-014 VIN = 24V V0UT = 5V I0UT = 1A CH1 CH2 CH1: VOUT, 50mV/div CH2: VSW, 10V/div TIME: 4µs/div ACT4501-015 Start up with EN VIN = 12V V0UT = 5V I0UT = 1A CH1 CH2 CH1: EN, 1V/div CH2: VOUT, 1V/div TIME: 2ms/div

Rev 2, 14-Nov-12 Innovative PowerTM - 13 - www.active-semi.com Copyright © 2012 Active-Semi, Inc. TYPICAL PERFORMANCE CHARACTERISTICS CONT’D (Circuit of Figure 7, IISET = 1A, L = 82µH, CIN = 10µF, COUT = 22µF, TA = 25°C, unless otherwise specified.) Load Step Waveforms ACT4501-017 VIN = 12V V0UT = 5V IISET = 1A CH1 CH2 CH1: VOUT, 200mV/div CH2: IOUT, 1A/div TIME: 400μs/div ACT4501-018 Load Step Waveforms VIN = 24V V0UT = 5V IISET = 1A CH1 CH2 CH1: VOUT, 200mV/div CH2: IOUT, 1A/div TIME: 400μs/div ACT4501-016 Start up with EN CH1 CH2 CH1: EN, 1V/div CH2: VOUT, 1V/div TIME: 2ms/div VIN = 24V V0UT = 5V IISET = 1A

Rev 2, 14-Nov-12 Innovative PowerTM - 14 - www.active-semi.com Copyright © 2012 Active-Semi, Inc. TYPICAL PERFORMANCE CHARACTERISTICS CONT’D (Circuit of Figure 7, IISET = 1A, L = 82µH, CIN = 10µF, COUT = 22µF, TA = 25°C, unless otherwise specified.) ACT4501-022 Short Circuit Recovery VIN = 24V V0UT = 5V IISET = 1A CH1 CH2 CH3 CH1: VOUT, 2V/div CH2: IOUT, 1A/div CH3: VSW, 20V/div TIME: 40µs/div ACT4501-020 Short Circuit Recovery VIN = 12V V0UT = 5V IISET = 1A CH1 CH2 CH1: VOUT, 2V/div CH2: IOUT, 1A/div CH3: VSW, 10V/div TIME: 40µs/div CH3 Short Circuit ACT4501-019 VIN = 12V V0UT = 5V IISET = 1A CH1 CH2 CH1: VOUT, 2V/div CH2: IOUT, 1A/div CH3: VSW, 10V/div TIME: 40µs/div CH3 ACT4501-021 Short Circuit VIN = 24V V0UT = 5V IISET = 1A CH1 CH2 CH1: VOUT, 2V/div CH2: IOUT, 1A/div CH3: VSW, 20V/div TIME: 40µs/div CH3

Rev 2, 14-Nov-12 Innovative PowerTM - 15 - www.active-semi.com Copyright © 2012 Active-Semi, Inc. PACKAGE OUTLINE SOP-8 PACKAGE OUTLINE AND DIMENSIONS SYMBOL DIMENSION IN MILLIMETERS DIMENSION IN INCHES MIN MAX MIN MAX A 1.350 1.750 0.053 0.069 A1 0.100 0.250 0.004 0.010 A2 1.350 1.550 0.053 0.061 B 0.330 0.510 0.013 0.020 C 0.190 0.250 0.007 0.010 D 4.700 5.100 0.185 0.201 E 3.800 4.000 0.150 0.157 E1 5.800 6.300 0.228 0.248 e 1.270 TYP 0.050 TYP L 0.400 1.270 0.016 0.050 θ 0° 8° 0° 8° A L C E D B e θ Active-Semi, Inc. reserves the right to modify the circuitry or specifications without notice. User s should evaluate each product to make sure that it is suitable for their applicat ions. Active-Semi products are not intended or authorized for use as critical components in life-support dev ices or systems. Active-Semi, Inc. does not assume any liability arising out of the use of any product or circuit described in this datasheet, nor does it convey any patent license. Active-Semi and its logo are trademarks of Active-Semi, Inc. For more information on this and other products, contact sales@active-semi.com or visit http://www.active-semi.com. is a registered trademark of Active-Semi.

Product Information

ACT4501 specifications and overview.

Summary

1.25A CC/CV Step-Down DC/DC Converter Rev 2, 14-Nov-12

Description

1.25A CC/CV Step-Down DC/DC Converter Rev 2, 14-Nov-12

Source title ACT4501 Datasheet(PDF) - Active-Semi, Inc

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