MAX1513ETP+T Maxim Integrated Products, MAX1513ETP+T Datasheet - Page 24

• Manufacturer Part Number: MAX1513ETP+T
• Description: IC CNTRLR TFT-LCD PS 20-TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX1513ETP+T

• Applications: Controller, TFT, LCD
• Voltage - Input: 2.7 ~ 5.5 V
• Number Of Outputs: 1
• Voltage - Output: 2.7 ~ 50 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

For highest efficiency, always choose the lowest num-
ber of charge-pump stages that meet the output volt-
age requirement. Figures 13 and 14 show the positive
and negative charge-pump output voltages for a given
V
The number of positive charge-pump stages is given by:
where n
stages, V
put, V
the forward-voltage drop of the charge-pump diode,
and V
ulator. Use V
The number of negative charge-pump stages is given by:
where n
stages, V
output, V
is the forward-voltage drop of the charge-pump diode,
and V
ulator. Use V
The above equations are derived based on the
assumption that the first stage of the positive charge
pump is connected to V
negative charge pump is connected to ground.
TFT-LCD Power-Supply Controllers
Figure 13. Positive Charge-Pump Output Voltage vs. V MAIN
24
MAIN
______________________________________________________________________________________
DROPOUT
DROPOUT
MAIN
Selecting the Number of Charge-Pump Stages
for one-, two-, and three-stage charge pumps.
n
NEG
POS
MAIN
POS
GON
GOFF
60
50
40
30
20
10
n
is the main step-up regulator output, V
0
DROPOUT
DROPOUT
NEG
is the number of positive charge-pump
is the number of negative charge-pump
2
is the gate-on linear-regulator REG P out-
=
is the main step-up regulator output, V
V
2-STAGE CHARGE-PUMP
D
is the dropout margin for the linear reg-
is the dropout margin for the linear reg-
is the gate-off linear-regulator REG N
= 0.3V TO 1V
V
OUTPUT VOLTAGE vs. V
=
GON
4
POSITIVE CHARGE-PUMP
-
V
= 0.3V.
= 0.3V.
GOFF
6
V
+
V
MAIN
MAIN
MAIN
3-STAGE CHARGE-PUMP
V
1-STAGE CHARGE-PUMP
MAIN
V
DROPOUT
8
(V)
+
and the first stage of the
- 2
- 2
V
10
DROPOUT
×
MAIN
×
12
V
V
-
D
D
V
MAIN
14
D
is
D
Sometimes fractional stages are more desirable for bet-
ter efficiency. This can be done by connecting the first
stage to V
charge-pump stage is powered from V
above equations become:
Increasing the flying capacitor (C
effective source impedance and increases the output-
current capability. Increasing the capacitance indefinite-
ly has a negligible effect on output-current capability
because the switch resistance and the diode impedance
place a lower limit on the source impedance. A 0.1µF
ceramic capacitor works well in most low-current appli-
cations. The flying capacitor’s voltage rating must
exceed the following:
where n is the stage number in which the flying capaci-
tor appears, and V
main step-up regulator.
Increasing the output capacitance or decreasing the
ESR reduces the output ripple voltage and the peak-to-
peak voltage during load transients. With ceramic
Figure 14. Negative Charge-Pump Output Voltage vs. V MAIN
n
n
POS
NEG
-10
-15
-20
-25
-30
-35
-40
-45
IN
-0
-5
or another available supply. If the first
2
CHARGE-PUMP
=
=
V
D
V
V
CHARGE-PUMP
= 0.3V TO 1V
-
OUTPUT VOLTAGE vs. V
CX
NEGATIVE CHARGE-PUMP
2-STAGE
GON
V
4
GOFF
MAIN
3-STAGE
Charge-Pump Output Capacitor
V
>
MAIN
6
V
+
n
MAIN
V
is the output voltage of the
+
MAIN
V
×
DROPOUT
8
V
-
(V)
V
DROPOUT
MAIN
-
2
10
2
1-STAGE
CHARGE-PUMP
×
X
×
MAIN
V
) value lowers the
Flying Capacitors
D
12
V
-
D
+
V
IN
14
IN
V
IN
, then the