uc3845-s08-t Unisonic Technologies, uc3845-s08-t Datasheet

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uc3845-s08-t

Manufacturer Part Number
uc3845-s08-t
Description
Pwm Controllers With Low Start-up Current
Manufacturer
Unisonic Technologies
Datasheet
UC3844/45
HIGH PERFORMANCE
CURRENT MODE PWM
CONTROLLERS
current mode controllers that specifically designed for Off-Line and
DC to DC converter applications with minimal external parts count.
duty cycle ranges and under-voltage lockout thresholds. The
UC3844 ideally suited to off-line applications with UVLO thresholds
of 16V
8.5V
* Operation output switching frequency up to 500 kHz
* Output deadtime adjustable from 50% to 70%
* Automatic feed forward compensation
* Latching PWM for cycle-by-cycle current limiting
* High current totem pole output
* Internally trimmed reference with under voltage lockout
* UVLO with hysteresis
* Low startup and operating current
www.unisonic.com.tw
Copyright © 2005 Unisonic Technologies Co., Ltd
The differences between UC3844 and UC3845 are the maximum
The UTC UC3844/3845 are high performance fixed frequency
(ON)
DESCRIPTION
FEATURES
UC3844-D08-T
UC3844-S08-R
UC3845-D08-T
UC3845-S08-R
UC3844-S08-T
UC3845-S08-T
ORDERING INFORMATION
(ON)
and 7.6V
Normal
and 10V
(OFF)
UNISONIC TECHNOLOGIES CO., LTD
Order Number
(OFF)
for lower voltage applications.
, and UC3845 has UVLO thresholds of
Lead Free Plating
UC3844L-D08-T
UC3844L-S08-R
UC3845L-D08-T
UC3845L-S08-R
UC3844L-S08-T
UC3845L-S08-T
Package
SOP-8
SOP-8
SOP-8
SOP-8
DIP-8
DIP-8
LINEAR INTEGRATED CIRCUIT
*Pb-free plating product number:
Tape Reel
Tape Reel
UC3844L/UC3845L
Packing
Tube
Tube
Tube
Tube
QW-R103-010,C
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uc3845-s08-t Summary of contents

Page 1

... Order Number Normal Lead Free Plating UC3844-D08-T UC3844L-D08-T UC3844-S08-R UC3844L-S08-R UC3844-S08-T UC3844L-S08-T UC3845-D08-T UC3845L-D08-T UC3845-S08-R UC3845L-S08-R UC3845-S08-T UC3845L-S08-T www.unisonic.com.tw Copyright © 2005 Unisonic Technologies Co., Ltd LINEAR INTEGRATED CIRCUIT *Pb-free plating product number: UC3844L/UC3845L Package Packing DIP-8 Tube SOP-8 Tape Reel SOP-8 ...

Page 2

... The output switches at one-half the oscillator frequency Positive supply Reference output, provides charging current for capacitor C REF UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw LINEAR INTEGRATED CIRCUIT FUNCTION to Vref and capacitor C to ground. Operation to 1 MHz is possible though resistor R ...

Page 3

... UC3844/45 BLOCK DIAGRAM UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw LINEAR INTEGRATED CIRCUIT QW-R103-010 ...

Page 4

... ERROR AMPLIFIER SECTION Voltage Feedback Input High Output Voltage Swing Low Sink Output Current Source Input Bias Current Open Loop Voltage Gain Power Supply Rejection Ratio Unity Gain Bandwidth UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw LINEAR INTEGRATED CIRCUIT (Ta=25°C) SYMBOL (I +Iz OUT W V ...

Page 5

... Max Duty Cycle Min TOTAL DEVICE Power Supply Zener Voltage Power Supply Current UC3845 (Note 4) UC3844 Note: 1. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible. 2. This parameter is measured at the latch trip point with V 3. Comparator gain is defined as: 4 ...

Page 6

... Oscillator Frequency, I OSC Error Amp Open Loop Gain Phase vs. Frequency 100 80 Gain -20 10 100 1.0k 10k 100k Frequency, f (Hz) UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com. 15V 25℃ 500k 1.0M 10k (Hz 15V 2.0V ~ 4.0V ...

Page 7

... 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. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw LINEAR INTEGRATED CIRCUIT ...

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