TC7129CKW Microchip Technology, TC7129CKW Datasheet - Page 10

• Manufacturer Part Number: TC7129CKW
• Description: IC ADC 4 1/2DGT LCD DVR 44-MQFP
• Manufacturer: Microchip Technology

Specifications of TC7129CKW

• Display Type: LCD
• Configuration: 7 Segment
• Digits Or Characters: A/D 4.5 Digits
• Current - Supply: 800µA
• Voltage - Supply: 6 V ~ 12 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 44-MQFP, 44-PQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Interface: -

4.2.3
Measurements are made with respect to power supply
ground. COMMON (pin 28) is connected to REF LO
(pin 35). A voltage doubler is needed, since the supply
voltage is less than the 6V minimum needed by the
TC7129. DGND (pin 36) must be isolated from power
supply ground (see Figure 4-3).
Figure 4-3:
a +5V Power Supply.
4.3
External logic can be directly referenced to DGND
(pin 36), provided that the supply current of the external
logic does not exceed the sink current of DGND
(Figure 4-4). A safe value for DGND sink current is
1.2 mA. If the sink current is expected to exceed this
value, a buffer is recommended (see Figure 4-5).
DS21459D-page 10
TC7129
TC7660
Connecting to External Logic
GND
+5V
V+
+5V Power Supply
8
3
2
4
5
0.1 µF
0.1 µF
10 µF
+
+
36
10 µF
Powering the TC7129 From
DGND
TC7129
V–
V+
23
24
34
28
33
32
35
V
IN
+
–
Figure 4-4:
Directly to DGND.
Figure 4-5:
to DGND with Buffer.
4.4
For most applications, V
directly to DGND (pin 36). For applications with a wide
temperature range, some LCDs require that the drive
levels vary with temperature to maintain good viewing
angle and display contrast. Figure 4-6 shows two
circuits that can be adjusted to give temperature com-
pensation of about 10 mV/°C between V+ (pin 24) and
V
have a low turn-on voltage because V
exceed 0.3V below DGND.
DISP
. The diode between DGND and V
Temperature Compensation
External
I
Logic
LOGIC
External
Logic
I
LOGIC
External Logic Referenced
External Logic Referenced
© 2006 Microchip Technology Inc.
DISP
+
–
36
(pin 19) can be connected
36
DGND
DGND
TC7129
TC7129
V
V-
+
V–
24
23
V+
24
23
DISP
DISP
cannot
should