MAX1620EEE+ Maxim Integrated Products, MAX1620EEE+ Datasheet - Page 15

• Manufacturer Part Number: MAX1620EEE+
• Description: IC LCD BIAS SUPP DGTL ADJ 16QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX1620EEE+

• Applications: LCD Display
• Current - Supply: 150µA
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Output Current: 0.07 A
• Input Voltage: 1.8 V to 20 V
• Switching Frequency: 300 KHz
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 9. MAX1621 Serial-Interface Read Example
The MAX1620/MAX1621 output voltage can be adjusted
manually or via a digital interface. In addition, positive
bias voltage can be switched with LCDON using an
external PFET or PNP transistor.
The minimum output voltage is set with a resistor-divider
(R4-R5, Figure 4) from V
voltage is 1.5V. Choose R4 to be 300kΩ so that the cur-
rent in the divider is about 5µA. Determine R5 as follows:
__________and Component Selection
CONDITION
SDA
SCL
START
ADDRESS BIT
SIGNIFICANT
R5 = R4 x (V
MOST
Setting the Minimum Output Voltage
______________________________________________________________________________________
Digitally Adjustable LCD Bias Supplies
OUT
OUT,MIN
Design Procedure
to AGND. The FB threshold
Output Adjustment
- V
FB
) / V
FB
ADDRESS BIT
SIGNIFICANT
LEAST
R/W BIT
ACKNOWLEDGE
SLAVE PULLS
SDA LOW
SLAVE
For example, if V
Mount R4 and R5 close to the FB pin to minimize para-
sitic capacitance.
For a negative output voltage, the FB threshold voltage
is 0V, and R4 is placed between FB and REF (Figures 5
and 6). Again, choose R4 to be 300kΩ so that the cur-
rent in the divider is about 5µA. Then determine R5 as
follows:
For example, if V
SIGNIFICANT
DATA BIT
MOST
POK
R5 = 300kΩ x (12.5 - 1.5) / (1.5) = 2.2MΩ
R5 = 300kΩ x (12.5) / (1.5) = 2.5MΩ
R5 = R4 x V
OUT,MIN
OUT,MIN
MAX1621 DRIVES SDA
D4
= 12.5V:
= -12.5V:
OUT,MIN
D3
D2
/ V
REF
D1
D0
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