UC1854B

UC2854A, UC2854B

UC3854A, UC3854B

SLUS329B − JUNE 1998 − REVISED FEBRUARY 2005

2

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DESCRIPTION (continued)

The UC3854A/B products improve upon the UC3854 by offering a wide bandwidth, low offset current amplifier,

a faster responding and improved accuracy enable comparator, a VREF GOOD comparator, UVLO threshold

options (16 V/10 V for offline, 10.5 V/10 V for startup from an auxiliary 12 V regulator), lower startup supply

current, and an enhanced multiply/divide circuit. New features like the amplifier output clamps, improved

amplifier current sinking capability, and low offset VAC pin reduce the external component count while improving

performance. Improved common mode input range of the multiplier output/current amplifier input allow the

oscillator charging current and has no effect on clamping the maximum multiplier output current. This current

is now clamped to a maximum of 2

power limiting during brownout and extreme low line conditions.

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

ABSOLUTE MAXIMUM RATINGS

over operating free-air temperature range unless otherwise noted(1)

UCX854A, UCX854B

UNIT

Supply voltage, VCC

22

V

GTDRV current, IGTDRV

Continuous

0.5

A

GTDRV Current, IGTDRV

50% duty cycle

1.5

A

Input voltage

VSENSE, VRMS, ISENSE MOUT

11

V

Input voltage

PKLMT

5

V

Input current

RSET, IAC, PKLMT, ENA

10

mA

Power dissipation

1

W

Junction temperature, TJ

−55 to 150

Storage temperature, Tstg

−65 to 150

°C

Lead temperature, Tsol, 1,6 mm (1/16 inch) from case for 10 seconds

300

C

(1) Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only,

and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is

not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltages are with respect to

GND. Currents are positive into and negative out of, the specified terminal. ENA input is internally clamped to approximately 10 V.

RECOMMENDED OPERATING CONDITIONS

MIN

MAX

UNIT

Supply voltage, VCC

10

20

V

UC1854X

−55

125

Operating junction temperature, TJ

UC2854X

−40

85

°C

Operating junction temperature, TJ

UC3854X

0

70

C