1

1

COMP

2

3

4

Sense

OSC

Gnd

8

7

6

5

Gnd

OSC

COMP

Sense

Output

Enable

5V

Reference

Internal

Bias

NOR

S

R

PWM

Latch

Current

Sensing

Comparator

Oscillator

1 V

R

2 R

Error

Amplifier

+

–

8.0V/7.4V

2.50V

Set/

Reset

Undervoltage

Lock-out Circuit

Pwr Gnd

s

Optimized for Off-line

Control

s

Internally Trimmed

Temperature

Compensated Oscillator

s

Maximum Duty-cycle

Clamp

s

Output Stage Enabled

s

Low Start-up Current

s

Pulse-by-pulse Current

Limiting

s

Improved Undervoltage

Lockout

s

Double Pulse Suppression

s

1% Trimmed Bandgap

Reference

s

High Current Totem Pole

Output

Package Options

8 Lead PDIP

10

7

14

13

12

8

1

2

3

4

5

6

11

9

COMP

NC

NC

Sense

NC

OSC

NC

Pwr Gnd

Gnd

14 Lead SO Narrow

Automotive Current Mode PWM

Control Circuit

CS2841B

Description

The CS2841B provides all the nec-

essary features to implement off-

line fixed frequency current-mode

control with a minimum number of

external components.

The CS2841B (a variation of the

CS-2843A) is designed specifically

for use in automotive operation.

The low start threshold voltage of

8.0V (typ), and the ability to sur-

vive 40V automotive load dump

transients are important for auto-

motive subsystem designs. The

CS-2841 series has a history of

quality and reliability in automo-

tive applications.

The CS2841B incorporates a preci-

sion temperature-controlled oscil-

lator with an internally trimmed

discharge current to minimize vari-

ations in frequency. Duty-cycles

greater than 50% are also possible.

stabilized before the output stage

is enabled. Ion implant resistors

provide tighter control of under-

voltage lockout.

Block Diagram

Absolute Maximum Ratings

Supply Voltage (Low Impedance Source)...................................................40V

Output Current ...............................................................................................±1A

Output Energy (Capacitive Load) .................................................................5µJ

Error Amp Output Sink Current...............................................................10mA

Lead Temperature Soldering

Wave Solder (through hole styles only) ..........10 sec. max, 260°C peak

Reflow (SMD styles only) ...........60 sec. max above 183°C, 230°C peak

Features

Rev. 6/23/99

Cherry Semiconductor Corporation

2000 South County Trail, East Greenwich, RI 02818

Tel: (401)885-3600 Fax: (401)885-5786

Email: info@cherry-semi.com

Web Site: www.cherry-semi.com

A

Company

®