MAX8738EUA Maxim Integrated Products, MAX8738EUA Datasheet - Page 9

• Manufacturer Part Number: MAX8738EUA
• Description: LCD Drivers
• Manufacturer: Maxim Integrated Products

Specifications of MAX8738EUA

• Maximum Clock Frequency: 100 KHz
• Operating Supply Voltage: 4.5 V to 20 V
• Maximum Power Dissipation: 362 mW
• Maximum Operating Temperature: + 85 C
• Package / Case: uMAX-8
• Maximum Supply Current: 60 uA
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1) Choose the maximum VCOM level (V
2) Select R1 between 10k
3) Calculate R2:
4) Calculate R
5) Verify that I
6) If I
Figure 4. Replacement of Mechanical Potentiometer Circuit
mum VCOM level (V
voltage (V
acceptable power loss from the AVDD supply rail.
a larger value for R1.
SET
I
SET MAX
exceeds 120µA, return to step 2 and choose
R
SET
(
POTENTIOMETER
R
AVDD
MECHANICAL
SET(MAX)
2
R
R
R
SET
A
B
C
AVDD
)
_______________________________________________________________________________________
:
).
(
20
V
AVDD
20
does not exceed 120µA:
MIN
V
(
V
AVDD
V
MAX
MAX
V
MAX
), and the AVDD supply
R
and 500k
SET
EEPROM-Programmable TFT VCOM
V
MAX
V
MIN
)
120
)
MAX
VCOM
based on the
R
A
1
R1 = R
R2 = R
R
), the mini-
R
SET
1
Calibrator with I
=
A
B
R
+ R
A
x (R
C
20 x R
B
+ R
B
C
)
7) The resulting resolution is:
A complete design example is given below:
1) V
2) If R1 = 200k , then R2 = 200k and
3) I
4) Resolution = 15.75mV.
Existing VCOM adjustment circuits using conventional
mechanical potentiometers can be translated into
MAX8738 circuits. Figures 4 and 5 show two common
adjustment circuits and their equivalent MAX8738 circuits.
EQUIVALENT CIRCUIT
GND
R
SET(MAX)
MAX8738
MAX
MAX8738
SET
R
SET
= 24.9k .
= 5V, V
Translating Existing Potentiometer
AVDD
SET
OUT
= 20µA.
(
MIN
AVDD
V
MAX
R2
R1
= 3V, V
127
2
V
MIN
C Interface
AVDD
)
= 10V.
VCOM
Circuits
9