Document
DATA SHEET www.onsemi.com
High Performance Current Mode Controllers
UC3842B, UC3843B,
8 1
PDIP−8 N SUFFIX CASE 626
UC2842B, UC2843B
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
• 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
VCC 7(12)
14 1
8 1
SOIC−14 D SUFFIX CASE 751A
SOIC−8 D1 SUFFIX CASE 751
PIN CONNECTIONS
Compensation 1 Voltage Feedback 2
Current Sense 3 RT/CT 4
8 Vref 7 VCC 6 Output 5 GND
(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 17 of this data sheet.
DEVICE MARKING INFORMATION
See general marking information in the device marking section on page 19 of this data sheet.
Vref
8(14)
R
5.0V Reference
VCC Undervoltage
Lockout
Vref
R
Undervoltage
VC
Lockout
7(11)
RT/CT
Oscillator
Output
4(7)
Voltage
Feedback
+
Input
-
Latching PWM
6(10) Power Ground
5(8)
2(3)
Output Compensation
1(1)
Error Amplifier
GND 5(9)
Current
Sense 3(5) Input
Pin numbers in parenthesis are for the D suffix SOIC−14 package.
Figure 1. Simplified Block Diagram
© Semiconductor Components Industries, LLC, 2013
1
August, 2021 − Rev. 18
Publication Order Number: UC3842B/D
UC3842B, UC3843B, UC2842B, UC2843B
MAXIMUM RATINGS
Rating Bias and Driver Voltages (Zero Series Impedance, see also Total Device spec) Total Power Supply and Zener Current Output Current, Source or Sink Output Energy (Capacitive Load per Cycle)
Symbol VCC, VC (ICC + IZ)
IO W
Value 30 30 1.0 5.0
Unit V mA A mJ
Current Sense, Voltage Feedback, Vref and Rt/Ct Inputs
Compensation
Output
Error Amp Output Sink Current
Power Dissipation and Thermal Characteristics D Suffix, Plastic Package, SOIC−14 Case 751A Maximum Power Dissipation @ TA = 25°C Thermal Resistance, Junction−to−Air D1 Suffix, Plastic Package, SOIC−8 Case 751 Maximum Power Dissipation @ TA = 25°C Thermal Resistance, Junction−to−Air N Suffix, Plastic Package, Case 626 Maximum Power Dissipation @ TA = 25°C Thermal Resistance, Junction−to−Air
Operating Junction Temperature
Operating Ambient Temperature
UC3842B, UC3843B UC2842B, UC2843B
UC2843D UC3842BV, UC3843BV
Vin Vcomp
Vo
IO
PD RqJA
PD RqJA
PD RqJA
TJ TA
−0.3 to + 5.5 −0.3 to + 7.2 −0.3 to VCC or
VC + 0.3 10
862 145
702 178
1.25 100 +150
0 to 70 −25 to + 85 −40 to +85 −40 to +105
V V V
mA
mW °C/W
mW °C/W
W °C/W
°C °C
Storage Temperature Range
Tstg
−65 to +150
°C
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality should not be assumed, damage may occur and reliability may be affected. 1. This device series contains ESD protection and exceeds the following tests:
Human Body Model 4000 V per JEDEC Standard JESD22-A114B Machine Model Method 200 V per JEDEC Standard JESD22-A115-A 2. This device contains latch-up protection and exceeds 100 mA per JEDEC Standard JESD78
www.onsemi.com 2
UC3842B, UC3843B, UC2842B, UC2843B
ELECTRICAL CHARACTERISTICS (VCC = 15 V [Note 3], RT = 10 k, CT = 3.3 nF. For typical values TA = 25°C, for min/max values TA is the operating ambient temperature range that applies [Note 4], unless otherwise noted.)
UC284XB, UC2843D
UC384XB, XBV
Characteristics
Symbol Min Typ Max Min Ty.