
Semiconductor Components Industries, LLC, 2005
November, 2005 Rev. 8
1
Publication Order Number:
UC3842A/D
UC3842A, UC3843A,
UC2842A, UC2843A
High Performance
Current Mode Controllers
The UC3842A, UC3843A series of high performance fixed
frequency current mode controllers are specifically designed for
offline and DCtoDC 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, cyclebycycle
current limiting, programmable output deadtime, and a latch for single
pulse metering.
These devices are available in an 8pin dualinline 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 UCX842A has UYLO thresholds of 16 V (on) and 10 V (off),
ideally suited for offline converters. The UCX843A is tailored for
lower voltage applications having UVLO thresholds of 8.5 V (on) and
7.6 V (off).
Features
Trimmed Oscillator Discharge Current for Precise Duty Cycle
Control
Current Mode Operation to 500 kHz
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
Direct Interface with ON Semiconductor SENSEFET
Products
PbFree Packages are Available
14
SOIC14
D SUFFIX
CASE 751A
1
See detailed ordering and shipping information in the package
dimensions section on page 15 of this data sheet.
ORDERING INFORMATION
See general marking information in the device marking
section on page 16 of this data sheet.
DEVICE MARKING INFORMATION
1
8
PDIP8
N SUFFIX
CASE 626
PIN CONNECTIONS
(Top View)
V
ref
(Top View)
Compensation
Voltage Feedback
Current Sense
R
T
/C
T
V
ref
V
CC
Output
GND
1
2
3
4
5
6
7
8
Compensation
NC
Voltage Feedback
NC
Current Sense
NC
R
T
/C
T
NC
V
CC
V
C
Output
GND
Power Ground
1
2
3
4
5
6
7
9
8
10
11
12
13
14
1
8
SOIC8
D1 SUFFIX
CASE 751
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