UC3842A, UC3843A, UC2842A, UC2843A

http://onsemi.com

2

Figure 1. Simplified Block Diagram

5.0V

Reference

Latching

PWM

Undervoltage

Lockout

Oscillator

Error

Amplifier

7(12)

7(11)

Output

6(10)

Power

Ground

5(8)

3(5)

Current

Sense

Input

8(14)

4(7)

2(3)

1(1)

GND

5(9)

Voltage

Feedback

Input

R

R

+

−

Undervoltage

Lockout

Output

Compensation

Pin numbers in parenthesis are for the D suffix SOIC−14 package.

MAXIMUM RATINGS

Rating

Symbol

Value

Unit

Bias and Driver Voltages (Zero Series Impedance, see also Total Device spec)

30

V

Total Power Supply and Zener Current

30

mA

Output Current, Source or Sink (Note 1)

1.0

A

Output Energy (Capacitive Load per Cycle)

W

5.0

mJ

Current Sense and Voltage Feedback Inputs

− 0.3 to + 5.5

V

Error Amp Output Sink Current

10

mA

Power Dissipation and Thermal Characteristics

D Suffix, Plastic Package

Thermal Resistance, Junction−to−Air

N Suffix, Plastic Package

Thermal Resistance, Junction−to−Air

862

145

1.25

100

mW

°C/W

W

°C/W

Operating Junction Temperature

+ 150

°C

Operating Ambient Temperature

UC3842A, UC3843A

UC2842A, UC2843A

0 to + 70

− 25 to + 85

°C

Storage Temperature Range

− 65 to + 150

°C

Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit

values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied,

damage may occur and reliability may be affected.

1. Maximum Package power dissipation limits must be observed.