UC1846/7

UC2846/7

UC3846/7

SLUS352A - JANUARY 1997 - REVISED MARCH 2002

•

Automatic Feed Forward Compensation

•

Programmable Pulse-by-Pulse Current

Limiting

•

Automatic Symmetry Correction in Push-pull

Configuration

•

Enhanced Load Response Characteristics

•

Parallel Operation Capability for Modular

Power Systems

•

Differential Current Sense Amplifier with

Wide Common Mode Range

•

Double Pulse Suppression

•

500mA (Peak) Totem-pole Outputs

•

±1% Bandgap Reference

• Under-voltage Lockout

• Soft Start Capability

• Shutdown Terminal

• 500kHZ Operation

Current Mode PWM Controller

The UC1846/7 family of control ICs provides all of the necessary

features 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 im

proved line regulation, enhanced load response characteristics, and

a simpler, easier-to-design control loop. Topological advantages in

clude inherent pulse-by-pulse current limiting capability, automatic

symmetry correction for push-pull converters, and the ability to par

allel “power modules" while maintaining equal current sharing.

Protection circuitry includes built-in under-voltage lockout and pro

grammable current limit in addition to soft start capability. A shut

down 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 sup

pression, deadline adjust capability, and a ±1% trimmed bandgap

reference.

The UC1846 features low outputs in the OFF state, while the

UC1847 features high outputs in the OFF state.

BLOCK DIAGRAM

OSC

E/A

7COMP

INV

C/S+

C/S-

SYNC

VIN

5.1 V

REFERENCE

REGULATOR

UVLO

LOCKOUT

2VREF

AOUT

BOUT

GND

0.5 mA

350 mV

0.5 V

F/F

CURRENT

LIMIT ADJUST

SHUTDOWN

UC1846

Output Stage

UC1847

Output Inverted

COMP

FEATURES DESCRIPTION

application

INFO

available

UDG-02057

UC1846/7

UC2846/7

UC3846/7

PACKAGE PIN FUNCTION

FUNCTION PIN

N/C 1

C/L SS 2

VREF 3

C/S- 4

C/S+ 5

N/C 6

E/A+ 7

E/A- 8

Comp 9

CT 10

N/C 11

RT 12

Sync 13

A Out 14

Gnd 15

N/C 16

VC 17

B Out 18

VIN 19

Shutdown 20

DIL-16, SOIC-16

(TOP VIEW)

J or N Package, DW Package

CONNECTION DIAGRAMS

ELECTRICAL CHARACTERISTICS

(Unless otherwise stated, these specifications apply for TA=-55°C to +125°C for

UC1846/7; -40°C to +85°C for the UC2846/7; and 0°C to +70°C for the UC3846/7;

IN=15V, RT=10k, CT=4.7nF, TA=TJ.)

UC1846/UC1847

UC3846/UC3847

PARAMETER TEST CONDITIONS UC2846/UC2847

MIN. TYP. MAX. MIN. TYP. MAX. UNITS

Reference Section

Output Voltage T

J=25°C, IO=1mA 5.05 5.10 5.15 5.00 5.10 5.20 V

Line Regulation V

IN=8V to 40V 5 20 5 20 mV

Load Regulation I

L=1mA to 10mA 3 15 3 15 mV

Temperature Stability Over Operating Range, (Note 2) 0.4 0.4 mV/°C

Total Output Variation Line, Load, and Temperature (Note 2) 5.00 5.20 4.95 5.25 V

Output Noise Voltage 10Hz ≤ f ≤10kHz, T

J=25°C (Note 2) 100 100 µV

Long Term Stability T

J=125°C, 1000 Hrs. (Note 2) 5 5 mV

Short Circuit Output Current V

REF=0V -10 -45 -10 -45 mA

Supply Voltage (Pin 15) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +40V

Collector Supply Voltage (Pin 13) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +40V

Output Current, Source or Sink (Pins 11, 14) . . . . . . . . . . . . . . . . . . . . . . . 500mA

Analog Inputs (Pins 3, 4, 5, 6, 16). . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +V

Reference Output Current (Pin 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -30mA

Sync Output Current (Pin 10). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -5mA

Error Amplifier Output Current (Pin 7) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -5mA

Soft Start Sink Current (Pin 1). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50mA

Oscillator Charging Current (Pin 9) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5mA

Power Dissipation at T

A=25°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000mW

Power Dissipation at T

C=25°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2000mW

Storage Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65°C to +150°C

Lead Temperature (soldering, 10 seconds) . . . . . . . . . . . . . . . . . . . . . . . . +300°C

ABSOLUTE MAXIMUM RATINGS (Note 1)

Note 1. All voltages are with respect to Ground, Pin 13. Currents are positive into,

negative out of the speficied terminal. Consult Packaging Section of Databook for

thermal limitations and considerations of packages. Pin numbers refer to DIL and

SOIC packages only.

PLCC-20, LCC-20

(TOP VIEW)

Q, L Packages

UC1846/7

UC2846/7

UC3846/7

UC1846/UC1847

UC3846/UC3847

PARAMETER TEST CONDITIONS UC2846/UC2847

MIN. TYP. MAX. MIN. TYP. MAX. UNITS

Oscillator Section

Initial Accuracy T

J=25°C 39 43 47 39 43 47 kHz

Voltage Stability V

IN=8V to 40V -1 2 -1 2 %

Temperature Stability Over Operating Range (Note 2) -1 -1 %

Sync Output High Level 3.9 4.35 3.9 4.35 V

Sync Output Low Level 2.3 2.5 2.3 2.5 V

Sync Input High Level Pin 8=0V 3.9 3.9 V

Sync Input Low Level Pin 8=0V 2.5 2.5 V

Sync Input Current Sync Voltage=3.9V, Pin 8=0V 1.3 1.5 1.3 1.5 mA

Error Amp Section

Input Offset Voltage 0.5 5 0.5 10 mV

Input Bias Current -0.6 -1 -0.6 -2 µA

Input Offset Current 40 250 40 250 nA

Common Mode Range V

IN=8V to 40V 0 VIN-2V 0 VIN-2V V

Open Loop Voltage Gain ∆V

O=1.2 to 3V, VCM=2V 80 105 80 105 dB

Unity Gain Bandwidth T

J=25°C (Note 2) 0.7 1.0 0.7 1.0 MHz

CMRR V

=0V to 38V, VIN=40V 75 100 75 100 dB

PSRR V

IN=8V to 40V 80 105 80 105 dB

Output Sink Current V

ID=-15mV to -5V, VPIN 7=1.2V 2 6 2 6 mA

Output Source Current V

ID=15mV to 5V, VPIN 7=2.5V -0.4 -0.5 -0.4 -0.5 mA

High Level Output Voltage R

L=(Pin 7) 15kΩ 4.3 4.6 4.3 4.6 V

Low Level Output Voltage 0.7 1 0.7 1 V

Current Sense Amplifier Section

Amplifier Gain V

PIN 3=0V, Pin 1 Open (Notes 3 & 4) 2.5 2.75 3.0 2.5 2.75 3.0 V

Maximum Differential Input Pin 1 Open (Note 3)

Signal (V

PIN 4-VPIN 3)RL (Pin 7)=15kW 1.1 1.2 1.1 1.2 V

Input Offset Voltage V

PIN 1=0.5V, Pin 7 Open (Note 3) 5 25 5 25 mV

CMRR V

CM=1V to 12V 60 83 60 83 dB

PSRR V

IN=8V to 40V 60 84 60 84 dB

Input Bias Current V

PIN 1=0.5V, Pin 7 Open (Note 3) -2.5 -10 -2.5 -10 µA

Input Offset Current V

PIN 1=0.5V, Pin 7 Open (Note 3) 0.08 1 0.08 1 µA

Input Common Mode Range 0 V

IN-3 0 VIN-3 V

Delay to Outputs T

J=25°C, (Note 2) 200 500 200 500 ns

Current Limit Adjust Section

Current Limit Offset V

PIN 3=0V, VPIN 4=0V, Pin 7 Open

(Note 3) 0.45 0.5 0.55 0.45 0.5 0.55 V

Input Bias Current V

PIN 5=VREF,VPIN 6=0V -10 -30 -10 -30 µA

Shutdown Terminal Section

Threshold Voltage 250 350 400 250 350 400 mV

Input Voltage Range 0 V

IN 0VIN V

Minimum Latching Current (Note 6)

PIN 1) 3.0 1.5 3.0 1.5 mA

ELECTRICAL

CHARACTERISTICS (cont.)

(Unless otherwise stated, these specifications apply for TA=-55°C to +125°C for UC1846/7;

-40°C to +85°C for the UC2846/7; and 0°C to +70°C for the UC3846/7; V

IN=15V, RT=10k,

T=4.7nF, TA=TJ.)

Part #	5962-8680601EA
Description	Current Mode PWM Controller 100mA 16-Pin CDIP - Rail/Tube
Category	IC
Availability	In Stock
Qty	6

Qty	Price
1 - 1	$25.45108
2 - 2	$20.24518
3 - 3	$19.08831
4 - 5	$17.73863
6 +	$15.81052

Manufacturer	Available	Qty
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5962-8680601EA

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