The 620LM Tester measurement circuitry is also
failsafe current limited, even under worst case
component failure.
E-7 . Ultra-Safe Power Supply Scheme
The +5 volt power supply is provided directly
by the batteries (for driving the LED displays
and digital logic). The ±5VD is used for driving
IC8, the low battery detection circuit. The ±15V
power supply is generated by IC7 for the digital
voltmeter (DVM) chip set (IC1 and IC2).
The ±5 VA is developed by one DC to DC
convertor circuitry: composed of Q103,Q104,
T102, D103, D104, IC102 for the negative
polarity. The other DC/DC convertor is
composed is composed of Q101, Q102, T101,
D101, D102 and IC101 for the positive polarity.
8
A
B
G
F
C
E
D
D.P.
SEGMENT PIN
A . . . . . . . . 1
B . . . . . . . . 13
C . . . . . . . . 10
D . . . . . . . . 8
E . . . . . . . . 7
F . . . . . . . . 2
G . . . . . . . . 11
D.P. . . . . . . . . 6
Common . . . . 14
8
PIN
1
2
3
4
5
6
7
PIN
14
13
12
11
10
9
8
Figure E4
- 620 series LED Display Pin Out Detail/Functions
