ICL7136CM44 Intersil, ICL7136CM44 Datasheet - Page 9

• Manufacturer Part Number: ICL7136CM44
• Description: IC ADC 3.5 DIGIT LCD 44-MQFP
• Manufacturer: Intersil

Specifications of ICL7136CM44

• Display Type: LCD
• Configuration: 7 Segment
• Digits Or Characters: A/D 3.5 Digits
• Current - Supply: 70µA
• Voltage - Supply: 4 V ~ 6 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 44-MQFP, 44-PQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Interface: -

FIGURE 5. EXCLUSIVE “OR” GATE FOR DECIMAL POINT DRIVE
ICL7136
TEST
V+
†
ONLY ONE INVERTER SHOWN
FOR CLARITY
THREE INVERTERS
TYPICAL SEGMENT OUTPUT
INTERNAL DIGITAL GROUND
BP
DECIMAL
SELECT
0.5mA
2mA
POINT
V+
SEGMENT
9
OUTPUT
CD4030
OSC 1
GND
V+
FROM COMPARATOR OUTPUT
40
FIGURE 6. ICL7136 DIGITAL SECTION
†
TO SWITCH DRIVERS
TO LCD
DECIMAL
POINTS
OSC 2
CLOCK
39
COUNTER
ICL7136
1000’s
b
OSC 3
a
Digital Section
Figures 6 shows the digital section for the ICL7136. In the
ICL7136, an internal digital ground is generated from a 6V
Zener diode and a large P-Channel source follower. This
supply is made stiff to absorb the relatively large capacitive
currents when the back plane (BP) voltage is switched. The
BP frequency is the clock frequency divided by 800. For
three readings/second this is a 60Hz square wave with a
nominal amplitude of 5V. The segments are driven at the
same frequency and amplitude and are in phase with BP
when OFF, but out of phase when ON. In all cases negligible
DC voltage exists across the segments.
The polarity indication is “on” for negative analog inputs. If IN
LO and IN HI are reversed, this indication can be reversed
also, if desired.
COUNTER
SEGMENT
DECODE
38
e
LCD PHASE DRIVER
100’s
f
INTERNAL
7
d
GROUND
DIGITAL
g
÷
a
4
c
LATCH
b
c
SEGMENT
COUNTER
DECODE
e
f
10’s
d
7
g
a
LOGIC CONTROL
c
b
SEGMENT
COUNTER
e
DECODE
f
V
1’s
d
TH
7
g
a
c
= 1V
b
21
÷
200
500Ω
BACKPLANE
6.2V
37
26
1
V+
TEST
V-
July 21, 2005
FN3086.6