Document
UNISONIC TECHNOLOGIES CO., LTD
US4651S
LINEAR INTEGRATED CIRCUIT
LOW COST POWER-SAVING MODE POWER-SWITCH FOR FLYBACK CONVERTERS
DESCRIPTION
The UTC US4651S is a high performance current mode power-switch ideally suited for low standby power. Drain start up make the power reliable on startup design and lower standby power. At no load condition, the IC operates in power-saving mode for lower standby power, decreasing frequency for Higher conversion efficiency at light load condition.
The UTC US4651S contains protection with automatic recovery including OLP (over load protection), OTP (over temperature protection), OVP (over voltage protection), UVLO (VDD over voltage
SOP-8
clamp and under voltage lockout).To protect the power MOSFET, Gate-drive output is fixed up to 16V max. The UTC US4651S contains protection OCP (cycle-by-cycle current limiting).
The internal slope compensation improves system stability at high PWM duty cycle output. Leading-edge blanking on current sense input removes the signal glitch, which offering minimal external component count in the design. Excellent EMI performance is achieved with UTC proprietary frequency hopping technique (ZL201020615247.1) together with soft driver control. Audio noise is eliminated due to switch frequency more than 20kHz during operation.
The UTC US4651S has such applications as: battery charger, power adaptor, set-top box power supplies, ink jet printers, open-frame SMPS.
FEATURES
* UTC proprietary frequency hopping technology for Improved EMI performance. * Power-saving mode for high light-load and standby efficiency * Soft Start * Dynamic peak current limiting for constant output power * Built-in synchronized slope compensation * OLP,OVP,OTP and VDD clamp for higher security
* Drain start up for lower standby power * Fixed switch frequency 65kHz * Gate output voltage clamped at 15V * Low start-up current * Cycle-by-cycle Current Limiting * Under voltage lockout (UVLO) * Few external components required
ORDERING INFORMATION
Ordering Number US4651SG-S08-R
Package SOP-8
Packing Tape Reel
US4651SG-S08-R
(1)Packing Type (2)Package Type (3)Green Package
(1) R: Tape Reel (2) S08: SOP-8 (3) G: Halogen Free and Lead Free
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QW-R129-003.B
US4651S
MARKING
LINEAR INTEGRATED CIRCUIT
PIN CONFIGURATION
VDD 1 GND 2
NC 3 CS 4
8 FB 7 NC 6 DRAIN 5 NC
PIN DESCRIPTION
PIN NO. 1 2
3, 5, 7
4
6
8
PIN NAME VDD GND NC
CS
DRAIN
FB
PIN TYPE P P
I O I
DESCRIPTION Power supply. Ground. No Connection Current sense input pin. Connected to MOSFET current sensing resistor node. Connected the primary lead of the transformer. Feedback input pin. The PWM duty cycle is determined by voltage level into this pin and CS pin input.
BLOCK DIAGRAM
VDD 1
NC 3/5/7 FB 8
UVLO Reference voltage
Frequency Hopping
Oscillator
UVLO
M2
6 DRAIN
OVP Logic Control OTP
Slope Compensation
Burstmode PWM COMP
Latch SQ RQ
Driver
.