UNISONIC TECHNOLOGIES CO., LTD P1885
PWM CONTROL 2A STEP-DOWN CONVERTER
DESCRIPTION
UTC P1885 consists of 2A step-down switching regulator control which includes a reference voltage source, oscillation circuit, error amplifier, internal PMOS and etc with PWM. UTC P1885 can provide low-ripple power, high efficiency, and excellent transient characteristics and an enable function, an over current protect function and a short circuit protect function are built inside, so the operation frequency will be reduced from 300KHz to 30KHz when OCP or SCP happens. And the PWM control circuit can vary the duty ratio linearly from 100 down to 0%. This converter also includes an error amplifier circuit as well as a soft-start circuit that prevents overshoot at startup. Also, to minimum external component count an internal compensation block is built in. These ICs can work as step-down switching regulators with the addition of an internal P-channel Power MOS, a coil, capacitors, and a diode connected externally. They provide such outstanding features: low current consumption. It is also suitable for the operation via an AC adapter because this converter can accommodate an input voltage up to 23V.
LINEAR INTEGRATED CIRCUIT
SOP-8
Lead-free: P1885L Halogen-free: P1885G
FEATURES
* Soft-start, Current Limit, Enable function * Thermal Shutdown function * Built-in internal SW P-channel MOS * Input voltage: 3.6V to 23V. * Output voltage: 0.8V to VCC. * Duty ratio: 0% to 100% PWM control * Oscillation frequency: 300KHz typ.
ORDERING INFORMATION
Normal P1885-S08-R Ordering Number Lead Free P1885L-S08-R Halogen Free P1885G-S08-R Package SOP-8 Packing Tape Reel
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P1885
PIN CONNECTIONS
LINEAR INTEGRATED CIRCUIT
PIN DESCRIPTIONS
PIN # 2 3 4 5 7 NAME VCC Output VSS FB EN DESCRIPTION IC power supply pin Switch Pin. Connect external inductor/diode here. Minimize trace area at this pin to reduce EMI. GND Feedback pin. Power-off pin H: Normal operation (Step-down operation) L: Step-down operation stopped (All circuits deactivated)
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P1885
BLOCK DIAGRAM
LINEAR INTEGRATED CIRCUIT
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P1885
ABSOLUTE MAXIMUM RATINGS
LINEAR INTEGRATED CIRCUIT
PARAMETER SYMBOL RATING UNIT VCC Pin Voltage VCC VSS-0.3 ~ VSS+25 V Feedback Pin Voltage VFB VSS-0.3 ~ VCC V EN Pin Voltage VEN VSS-0.3 ~ VIN+0.3 V Switch Pin Voltage VOUTPUT VSS-0.3 ~ VIN+0.3 V Power Dissipation PD Internally limited mW ℃ Operating Temperature TOPR -20 ~ +125 ℃ Storage Temperature TSTG -40 ~ +150 Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied.
THERMAL DATA
PARAMETER Junction-to-Ambient SYMBOL θJA MIN TYP 65 MAX UNIT °C/W
ELECTRICAL CHARACTERISTICS (VIN = 12V, Ta=25°C, unless otherwise specified)
PARAMETER SYMBOL CONDITIONS Input Voltage VIN Feedback Voltage VFB IOUT=0.1A Feedback Bias Current IFB(BIAS) IOUT=0.1A Switch Current ISW Standby Current ISTN-BY VEN=0V Line Regulation ΔVOUT/VOUT VIN=5V~23V, IOUT=0.2A Load Regulation ΔVOUT/VOUT IOUT=0.1~2A Oscillation Frequency fOSC Measure waveform at SW pin Frequency of Current Limit or Short Measure waveform at SW pin fOSC1 Circuit Protect VSH Evaluate oscillation at SW pin EN Pin Input Voltage Evaluate oscillation stop at SW pin VSL ISH EN Pin Input Leakage Current ISL Soft-Start Time TSS VIN=5V, VFB=0V Internal MOSFET RDS(ON) RDS(ON) VIN=12V, VFB=0V Efficiency η VIN=12V, VOUT=5V, IOUT=2A MIN. TYP. MAX. UNIT 3.6 23 V 0.784 0.8 0.816 V 0.1 0.5 μA 2.15 A 10 μA 1 2.1 % 0.2 0.5 % 240 300 360 KHz 10 0.79 0.72 20 -10 2 110 70 91 KHz V μA μA ms mΩ %
0.3
5 150 100
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P1885
FUNCTION DESCRIPTION
LINEAR INTEGRATED CIRCUIT
PWM Control The UTC P1885 consists of DC/DC converters which employ a PWM system. In this DC/DC converter, the pulse width varies in a range from 0 to 100% which is according to the load current. Cause the switching frequency remains constant the ripple voltage which produced by the switching can be removed easily through a filter. Therefore, these converters provide a low-ripple power over broad ranges of input voltage and load current. Under Voltage Lockout The under voltage lockout circuit makes sure that the outputs of high-side MOSFET driver remain in the off state after the supply voltage drops below 3.3V. When VCC rises above 3.5V normal operation resumes.
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P1885
TEST CIRCUITS
LINEAR INTEGRATED CIRCUIT
+
-
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P1885
TYPICAL APPLICATION CIRCUIT
LINEAR INTEGRATED CIRCUIT
VOUT L1 Value
VIN=12V, IMAX=2A 2.5V 3.3V 15uH 18uH
5V 22uH
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P1885
TYPICAL CHARACTERISTICS
Input Voltage vs. Frequency 320 315 310 305 300 295 290 285 280 275 270 0 5 10 15 20 Input Voltage, VIN (V) Line Regulation 5.00 4.95 4.90 4.85 4.80 4.75 4.70 0 VOUT=5V, IOUT=0.2A 4.99 4.98 4.97 4.96 4.95 4.94 4.93 4.92 4.91 4.90 5 10 15 20 Input Voltage, VIN (V) 25 4.89 0 25 VOUT=5V, IOUT=0.2A 0.84 0.83 0.82 0.81 0.80 0.79 0.78 0.77 0.76 0.75 0.74 0
LINEAR INTEGRATED CIRCUIT
Input Voltage vs. Feedback Voltage VOUT=5V, IOUT=0.2A
5
10 15 20 Input Voltage, VIN (V) Load Regulation VIN=12V
25
1.0 1.5 0.5 Output Current, IOUT (A)
2.0
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P1885
LINEAR INTEGRATED CIRCUIT
U TC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.
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