1

LTC1531

Self-Powered Isolated

Comparator

s

UL Recognized File E151738 to UL1577

s

Self-Powered Across Isolation Barrier

s

s

s

Zero-Cross Output for Line Power

s

Dual Differential Input Comparator

s

High Input Impedance Comparator

The LTC

comparator. An internal capacitive isolation barrier pro-

its output. The part provides UL-rated isolated compari-

sons without the need for an isolated supply since both

comparator power and output data are transmitted across

the capacitive barrier. The comparator data is transferred

differentially across the isolation barrier to provide high

common mode voltage and noise immunity.

The isolated side can supply a 2.5V reference output to

power external sensor circuits such as a thermistor bridge.

The dual differential comparator inputs allow for compari-

son of two differential voltages as well as single-ended

voltages. The powered side provides a latched data output

as well as a pulsed zero-cross comparator output for

controlling a triac. The part is available in a 28-lead SO

package.

Isolated Thermistor Temperature Controller

, LTC and LT are registered trademarks of Linear Technology Corporation.

s

Self-Powered Isolated Sensing

s

Isolated Temperature Control

s

Isolated Voltage Monitor

s

Isolated Switch Control

FEATURES

DESCRIPTIO

APPLICATIO S

–5.6V

5.6V

AC

120V

NEUTRAL

2N2222

LOAD

25

Ω

TECCOR

Q4008L4

OR EQUIVALENT

ISOGND

V1

ISOLATION

BARRIER

1531 TA01

VALID

GND

390

Ω

R5*1M

B = 3807

2.5V

20

µF

50V

1

µF

T

LTC1531

R2

47k

R1

680k

150

Ω

750

Ω

0.5W

+

–

THERM

30k

YSI 44008

R4

50k

SHDN

CMPOUT

ZCDATA

ZCPOS

ZCNEG

DATA

LED

1k

QD

C1

0.01

µF

3k

3W

1N4004

+

100

µF

+

+

1

1

1

1

*HYSTERESIS = 1

= ISOLATED GROUND

1

V3

V4

V2

R6

22k

DANGER!

LETHAL VOLTAGES

IN THIS SECTION!