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UC2845BVDR2G View Datasheet(PDF) - ON Semiconductor

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UC2845BVDR2G
ON-Semiconductor
ON Semiconductor ON-Semiconductor
UC2845BVDR2G Datasheet PDF : 19 Pages
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UC3844B, UC3845B,
UC2844B, UC2845B
High Performance
Current Mode Controllers
The UC3844B, UC3845B series are high performance fixed frequency
current mode controllers. They are specifically designed for OffLine
and dcdc converter applications offering the designer a costeffective
solution with minimal external components. These integrated circuits
feature an oscillator, a temperature compensated reference, high gain
error amplifier, current sensing comparator, and a high current totem pole
output ideally suited for driving a power MOSFET.
Also included are protective features consisting of input and
reference undervoltage lockouts each with hysteresis, cyclebycycle
current limiting, a latch for single pulse metering, and a flipflop
which blanks the output off every other oscillator cycle, allowing
output deadtimes to be programmed from 50% to 70%.
These devices are available in an 8pin dualinline and surface
mount (SOIC8) plastic package as well as the 14pin plastic surface
mount (SOIC14). The SOIC14 package has separate power and
ground pins for the totem pole output stage.
The UCX844B has UVLO thresholds of 16V (on) and 10V (off), ideally
suited for offline converters. The UCX845B is tailored for lower voltage
applications having UVLO thresholds of 8.5V (on) and 7.6V (off).
Features
Trimmed Oscillator for Precise Frequency Control
Oscillator Frequency Guaranteed at 250 kHz
Current Mode Operation to 500 kHz Output Switching Frequency
Output Deadtime Adjustable from 50% to 70%
Automatic Feed Forward Compensation
Latching PWM for CycleByCycle Current Limiting
Internally Trimmed Reference with Undervoltage Lockout
High Current Totem Pole Output
Undervoltage Lockout with Hysteresis
Low Startup and Operating Current
These Devices are PbFree and are RoHS Compliant
NCV Prefix for Automotive and Other Applications Requiring
Unique Site and Control Change Requirements; AECQ100
Qualified and PPAP Capable
VCC 7(12)
Vref
8(14)
RT/CT
4(7)
Voltage
Feedback
Input
2(3)
Output/
Compensation
1(1)
5.0V
Reference
R
Vref
R
Undervoltage
Lockout
Oscillator
Latching
PWM
Error
Amplifier
VCC
Undervoltage
Lockout
GND 5(9)
Pin numbers in parenthesis are for the D suffix SOIC-14 package.
Figure 1. Simplified Block Diagram
VC
7(11)
Output
6(10)
Power
Ground
5(8)
Current
Sense Input
3(5)
© Semiconductor Components Industries, LLC, 2013
1
August, 2013 Rev. 11
http://onsemi.com
8
1
14
1
8
1
PDIP8
N SUFFIX
CASE 626
SOIC14
D SUFFIX
CASE 751A
SOIC8
D1 SUFFIX
CASE 751
PIN CONNECTIONS
Compensation 1
Voltage Feedback 2
8 Vref
7 VCC
Current Sense 3
6 Output
RT/CT 4
5 GN
D
(Top View)
Compensation 1
NC 2
Voltage Feedback 3
NC 4
Current Sense 5
NC 6
RT/CT 7
14 Vref
13 NC
12 VCC
11 VC
10 Output
9 GND
8 Power Ground
(Top View)
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 15 of this data sheet.
DEVICE MARKING INFORMATION
See general marking information in the device marking
section on page 16 of this data sheet.
Publication Order Number:
UC3844B/D
 

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