Symbol

Parameter

Conditions

Min

Typ

Max

Units

ZENER REGULATOR

Regulator Voltage

756

V

Series Resistance

105

15

X

Temperature Stability

a

1

mV C

TOTAL SUPPLY CURRENT

38

6

mA

Note 1

For operation in ambient temperatures above 25 C the device must be derated based on a 150 C maximum junction temperature and a thermal resistance

of 101 CW junction to ambient for LM2907-8 and LM2917-8 and 79 CW junction to ambient for LM2907-14 and LM2917-14

Note 2

Note 3

c

c

Note 4

maximum value for R1 is limited by the output resistance of pin 3 which is greater than 10 MX typically

Note 5

10 kHz

The op ampcomparator is fully compatible with the ta-

chometer and has a floating transistor as its output This

feature allows either a ground or supply referred load of up

The two basic configurations offered include an 8-pin device

with a

ground referenced tachometer input and an internal

connection between the tachometer output and the op amp

non-inverting input This version is well suited for single

speed or frequency switching or fully buffered frequency to

voltage conversion applications

The more versatile configurations provide differential ta-

chometer input and uncommitted op amp inputs With this

version the tachometer input may be floated and the op

amp becomes suitable for active filter conditioning of the

tachometer output

Both of these configurations are available with an active

shunt regulator connected across the power leads The reg-

ulator clamps the supply such that stable frequency to volt-

age and frequency to current operations are possible with

any supply voltage and a suitable resistor

Test Circuit and Waveform

TLH7942 – 6

Tachometer Input Threshold Measurement

TLH7942 – 7

3