UC3842B, UC3843B,
UC2842B, UC2843B
High Performance
Current Mode Controllers
The UC3842B, UC3843B series are high performance fixed
frequency current mode controllers. They are specifically designed for
Off−Line and DC−DC converter applications offering the designer a
cost−effective solution with minimal external components. These
integrated circuits feature a trimmed oscillator for precise duty cycle
control, 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, cycle−by−cycle
current limiting, programmable output deadtime, and a latch for single
pulse metering.
These devices are available in an 8−pin dual−in−line and surface
mount (SOIC−8) plastic package as well as the 14−pin plastic surface
mount (SOIC−14). The SOIC−14 package has separate power and
ground pins for the totem pole output stage.
The UCX842B has UVLO thresholds of 16 V (on) and 10 V (off),
ideally suited for off−line converters. The UCX843B is tailored for
lower voltage applications having UVLO thresholds of 8.5 V (on) and
7.6 V (off).
Features
http://onsemi.com
8
1
PDIP−8
N SUFFIX
CASE 626
14
1
SOIC−14
D SUFFIX
CASE 751A
8
1
SOIC−8
D1 SUFFIX
CASE 751
•
•
•
•
•
•
•
•
•
•
Trimmed Oscillator for Precise Frequency Control
Oscillator Frequency Guaranteed at 250 kHz
Current Mode Operation to 500 kHz
Automatic Feed Forward Compensation
Latching PWM for Cycle−By−Cycle Current Limiting
Internally Trimmed Reference with Undervoltage Lockout
High Current Totem Pole Output
Undervoltage Lockout with Hysteresis
Low Startup and Operating Current
This is a Pb−Free and Halide−Free Device
V
CC
V
ref
8(14)
R
R
R
T
/C
T
4(7)
V
ref
Undervoltage
Lockout
Oscillator
Latching
PWM
+
-
PIN CONNECTIONS
Compensation
Voltage Feedback
Current Sense
R
T
/C
T
1
2
3
4
8
7
6
5
V
ref
V
CC
Output
GND
(Top View)
Compensation
NC
Voltage Feedback
NC
Current Sense
NC
R
T
/C
T
V
C
7(11)
Output
6(10)
Power
Ground
5(8)
Current
Sense
3(5) Input
1
2
3
4
5
6
7
14
13
12
11
10
9
8
7(12)
5.0V
Reference
V
CC
Undervoltage
Lockout
V
ref
NC
V
CC
V
C
Output
GND
Power Ground
(Top View)
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 17 of this data sheet.
Voltage
Feedback
Input
2(3)
Output
Compensation
1(1)
DEVICE MARKING INFORMATION
See general marking information in the device marking
section on page 19 of this data sheet.
Error
Amplifier
GND
5(9)
Pin numbers in parenthesis are for the D suffix SOIC−14 package.
Figure 1. Simplified Block Diagram
©
Semiconductor Components Industries, LLC, 2013
September, 2013
−
Rev. 17
1
Publication Order Number:
UC3842B/D
ONSEMI [ ON SEMICONDUCTOR ]
