UC3846N Fairchild Semiconductor, UC3846N Datasheet

Switching Converters, Regulators & Controllers PWM Control IC

UC3846N

Manufacturer Part Number
UC3846N
Description
Switching Converters, Regulators & Controllers PWM Control IC
Manufacturer
Fairchild Semiconductor
Datasheet

Specifications of UC3846N

Operating Temperature Range
0 C to + 70 C
Mounting Style
Through Hole
Package / Case
DIP-16
Lead Free Status / Rohs Status
Lead free / RoHS Compliant

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Features
• Automatic Feed Forward Compensation
• Programmable Pulse by Pulse Current Limiting
• Automatic Symmetry Correction in Push-Pull
• Enhanced Load Response Characteristics
• Parallel Operation Capability for Modulator Power
• Differential Current Sense Amplifier with Common Mode
• Double Pulse Suppression
• 200mA Totem-Pole Outputs
• Under-Voltage Lockout
• Soft-Start Capability
• Shutdown Terminal
• 500KHz Operation
Internal Block Diagram
©2000 Fairchild Semiconductor International
UC3846
SMPS Controller
Configuration
Systems
Range
2% Band gap Reference
10
Description
The UC3846 control IC provides all of the necessary fea-
tures to implement fixed frequency, current mode control
schemes while maintaining a minimum external parts count.
The superior performance of this technique can be measured
in improved line regulation, enhanced load response char-
acteristics, and a simpler, easier-to-design control loop.
Topological advantages include inherent pulse-by-pulse cur-
rent limiting capability, automatic symmetry correction for
push-pull converters, and the ability to parallel “power
module
circuitry includes built-in-under-voltage lockout and pro-
grammable current limit in addition to soft-start capability. A
shutdown function is also available which can initiate either
a complete shutdown with automatic restart or latch the
supply off. Other features include fully latched operation,
double pulse suppression, deadtime adjust capability, and
±2% trimmed bandgap reference. The UC3846 features low
outputs in the OFF state.
16-DIP
,,
while maintaining equal current sharing. Protection
1
www.fairchildsemi.com
Rev. 5.0

Related parts for UC3846N

UC3846N Summary of contents

Page 1

... Under-Voltage Lockout • Soft-Start Capability • Shutdown Terminal • 500KHz Operation Internal Block Diagram ©2000 Fairchild Semiconductor International Description The UC3846 control IC provides all of the necessary fea- tures to implement fixed frequency, current mode control schemes while maintaining a minimum external parts count. ...

Page 2

UC3846 Absolute Maximum Ratings Parameter Supply Voltage Collector Supply Voltage Output Current, Sink of Source (Peak) Reference Output Current Soft Start Sink Current Sync Output Current Error Amplifier Output Current Oscillator Changing Current Power Dissipation ( ...

Page 3

Electrical Characteristics (V = 15V +70 C, unless otherwise specified Parameter OSCILLATOR SECTION (Note 2) Initial Accuracy Frequency Change with Voltage Frequency Change with Temperature (Note 6) Sync Output High Level Sync Output Low Level ...

Page 4

UC3846 Electrical Characteristics (V =15V unless otherwise specified Parameter CURRENT LIMIT ADJUST SECTION Current Limit Offset Voltage (Note 1) Input Bias Current SHUTDOWN TERMINAL SECTION Threshold Voltage Input Voltage Range Minimum ...

Page 5

Output deadtime is determined by the external capacitor, C For large values (us) = l45C T d 2.2 by the formula: f KHz = ----------------------------------------- - OUTPUT DEADTIME(T Figure 1. UC3846 ...

Page 6

UC3846 A small PC filter may be required in some applications to reduce switch transients Differential input allows remote, noise free sensing. 6 Figure 3. Parallel Operation Figure 4. Pulse By Pulse Current Limiting Figure 5. Current Sense Amp Connections ...

Page 7

Mechanical Dimensions Package 6.40 0.20 0.252 0.008 #1 #8 7.62 0.300 16-DIP #16 #9 3.25 0.20 0.128 0.008 5.08 MAX 0.200 0.38 MIN 0.014 3.30 0.30 0.130 0.012 UC3846 7 ...

Page 8

... UC3846 Ordering Information Product Number Package UC3846N 16 DIP 8 Operating Temperature ...

Page 9

UC3846 9 ...

Page 10

... UC3846 LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR INTERNATIONAL. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, ...

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