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參數(shù)資料
| 型號： | MAX1518BETJ |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | TFT-LCD DC-DC Converter with Operational Amplifiers |
| 中文描述： | 3.5 A SWITCHING REGULATOR, 1380 kHz SWITCHING FREQ-MAX, QCC32 |
| 封裝： | 5 X 5 MM, 0.80 MM HEIGHT, MO-220WHHD-2, TQFN-32 |
| 文件頁數(shù)： | 20/25頁 |
| 文件大?。?/td> | 1308K |
| 代理商： | MAX1518BETJ |
M
TFT-LCD DC-DC Converter with
Operational Amplifiers
20
______________________________________________________________________________________
The number of negative charge-pump stages is given by:
where n
NEG
is the number of negative charge-pump
stages, V
GOFF
is the gate-off linear-regulator REG N
output, V
MAIN
is the main step-up regulator output, V
D
is the forward-voltage drop of the charge-pump diode,
and V
DROPOUT
is the dropout margin for the linear reg-
ulator. Use V
DROPOUT
= 0.3V.
The above equations are derived based on the
assumption that the first stage of the positive charge
pump is connected to V
MAIN
and the first stage of the
negative charge pump is connected to ground.
Sometimes fractional stages are more desirable for bet-
ter efficiency. This can be done by connecting the first
stage to V
IN
or another available supply. If the first
charge-pump stage is powered from V
IN
, then the
above equations become:
Flying Capacitors
Increasing the flying-capacitor (C
X
) value lowers the
effective source impedance and increases the output-
current capability. Increasing the capacitance indefinitely
has a negligible effect on output-current capability
because the internal switch resistance and the diode
impedance place a lower limit on the source imped-
ance. A 0.1μF ceramic capacitor works well in most
low-current applications. 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
is the output voltage of the
main step-up regulator.
Charge-Pump Output Capacitor
Increasing the output capacitance or decreasing the
ESR reduces the output ripple voltage and the peak-to-
peak transient voltage. With ceramic capacitors, the
output voltage ripple is dominated by the capacitance
value. Use the following equation to approximate the
required capacitor value:
where C
OUT_CP
is the output capacitor of the charge
pump, I
LOAD_CP
is the load current of the charge
pump, and V
RIPPLE_CP
is the peak-to-peak value of the
output ripple.
Charge-Pump Rectifier Diodes
Use low-cost silicon switching diodes with a current rat-
ing equal to or greater than two times the average
charge-pump input current. If it helps avoid an extra
stage, some or all of the diodes can be replaced with
Schottky diodes with an equivalent current rating.
Linear-Regulator Controllers
Output-Voltage Selection
Adjust the gate-on linear-regulator (REG P) output volt-
age by connecting a resistive voltage-divider from the
REG P output to AGND with the center tap connected
to FBP (Figure 1). Select the lower resistor of the divider
R5 in the range of 10k
to 30k
. Calculate the upper
resistor R4 with the following equation:
where V
FBP
= 1.25V (typ).
R
R
V
V
GON
FBP
4
5
1
=
×
C
I
f
V
OUT CP
LOAD CP
OSC
RIPPLE CP
_
_
_
≥
2
V
> ×
CX
MAIN
n
V
V
V
V
V
n
V
V
V
V
V
POS
GON
DROPOUT
MAIN
GOFF
MAIN
IN
D
NEG
DROPOUT
×
2
IN
D
=
+
+
×
2
=
+
+
n
V
V
×
2
V
V
NEG
GOFF
MAIN
DROPOUT
D
=
+
STEP-UP
CONTROLLER
MAX1518B
PGND
FB
LX
V
MAIN
>13V
V
IN
Figure 8. Operation with Output Voltages >13V Using
Cascoded MOSFET
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1518BETJ+ | 功能描述:LCD 驅(qū)動器 TFT-LCD DC-DC Conv w/Op Amps RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
| MAX1518BETJ+T | 功能描述:LCD 驅(qū)動器 TFT-LCD DC-DC Conv w/Op Amps RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
| MAX1518ETJ | 功能描述:LCD 驅(qū)動器 RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
| MAX1518ETJ+ | 功能描述:LCD 驅(qū)動器 TFT-LCD DC-DC Conv w/Op Amps RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
| MAX1518ETJ+T | 功能描述:LCD 驅(qū)動器 TFT-LCD DC-DC Conv w/Op Amps RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
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