8

UC1874-1,-2

UC2874-1,-2

UC3874-1,-2

amplifier. An ultra low power sleep mode is also invoked

from the SS pin. A voltage level below 0.5V on this pin

reduces total standby current to less than 50mA. Short

circuit protection is inherent to the average current mode

technique with proper compensation of the current

amplifier. To prevent operation of the MOSFETs with an

inadequete drive signal, an undervoltage lockout circuit

suppresses the output drivers until the input supply

voltage is sufficiently high enough for proper operation.

The UC3874-1 is intended for applications with logic level

MOSFETs and its VCC turn-on and turn-off thresholds

are 4.5V/4.4V respectively. The UC3874-2 is intended for

applications with standard MOSFETs and has UVLO

turn-on

and

turn-off

thresholds

of

10V

and

9V

respectively. The precision 2.5V reference can provide

20mA to power external circuitry. The reference output is

disabled during UVLO and sleep modes.

ORDERING INFORMATION

UVLO Turn

On/Off

Threshold

Package

Temperature

Range

1: 4.5V/4.4V

J: Ceramic DIL-18

1: –55°C to +125°C

2: 10V/9V

N: Plastic DIL-18

2: –40°C to +85°C

DW: SOIC-18

3: 0°C to +70°C

4

5

6

7

8

9

10

11

-75

-25

25

75

125

TEMPERATURE °C

TYPICAL PERFORMANCE INFORMATION

Figure 1. Supply Current

1.95

1.96

1.97

1.98

1.99

2

2.01

2.02

2.03

2.04

2.05

-50

-25

0

25

50

75

100

TEMPERATURE °C

80

90

100

110

120

130

140

-75

-25

25

75

125

TEMPERATURE °C

Figure 4. Oscillator Frequency vs. Temperature

(CT = 680pF)

560

600

640

680

720

760

-50

-25

0

25

50

75

100

TEMPERATURE °C

± 10µA)