參數(shù)資料
型號： MAX1514ETP
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： 穩(wěn)壓器
英文描述： TFT-LCD Power-Supply Controllers
中文描述： SWITCHING CONTROLLER, 1725 kHz SWITCHING FREQ-MAX, PQCC20
封裝： 4 X 4 MM, 0.80 MM HEIGHT, MO-220-VGGD, TQFN-20
文件頁數(shù)： 25/28頁
文件大小： 540K
代理商： MAX1514ETP
M
TFT-LCD Power-Supply Controllers
______________________________________________________________________________________
25
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.
The charge-pump output capacitor is typically also the
input capacitor for a linear regulator. Often, its value must
be increased to maintain the linear regulator’s stability.
Charge-Pump Rectifier Diodes
Use low-cost silicon switching diodes with a current rating
equal to or greater than twice the average charge-pump
input current. If their low forward voltage helps to avoid an
extra stage, some or all of the diodes can be replaced
with Schottky diodes with equivalent current ratings.
Linear-Regulator Controllers
Output-Voltage Selection
Adjust the positive linear-regulator (REG P, REG L, and
REG G) output voltages by connecting a resistive volt-
age-divider from their respective outputs to the analog
ground plane (which connects to GND) with the center
tap connected to FB_ (Figure 1). Select the lower resis-
tor of the divider in the range of 10k
to 30k
. Calculate
the upper resistor with the following equation:
where V
OUT
_ is the output voltage of the respective lin-
ear regulator, and V
FB
_ = 1.25V (typ).
Adjust the gate-off linear-regulator REG N output volt-
age by connecting a resistive voltage-divider from
V
GOFF
to REF with the center tap connected to FBN
(Figure 1). Select R4 between 20k
and 50k
.
Calculate R3 with the following equation:
where V
FBN
= 250mV, V
REF
= 1.25V. Note that REF can
only source up to 50μA; using a resistor less than 20k
for R4 results in higher bias current than REF can sup-
ply without degrading REF accuracy.
Pass-Transistor Selection
The pass transistor must meet specifications for current
gain (h
FE
), input capacitance, collector-emitter satura-
tion voltage, and power dissipation. The transistor’s
current gain limits the guaranteed maximum output cur-
rent to:
where I
DRV
is the minimum guaranteed base-drive cur-
rent and R
BE
is the pullup resistor connected between
the transistor’s base and emitter. Furthermore, the tran-
sistor’s current gain increases the linear regulator’s DC
loop gain (see the
Stability Requirements
section), so
excessive gain destabilizes the output. Therefore, tran-
sistors with current gain over 100 at the maximum out-
put current can be difficult to stabilize and are not
recommended unless needed to meet output-current
requirements.
The transistor’s saturation voltage at the maximum out-
put current determines the minimum input-to-output
voltage differential that the linear regulator supports.
Also, the package’s power dissipation limits the use-
able maximum power-dissipation capability of the tran-
sistor’s package, and mounting must exceed the actual
power dissipation in the device. The power dissipation
equals the maximum load current (I
LOAD(MAX)_LR
)
times the maximum input-to-output voltage differential:
where V
IN(MAX)_LR
is the maximum input voltage of the
linear regulator and V
OUT_LR
is the output voltage of
the linear regulator.
Stability Requirements
The MAX1513/MAX1514 linear-regulator controllers use
an internal transconductance amplifier to drive an
external pass transistor. The transconductance amplifi-
er, the pass transistor, the base-emitter resistor, and
the output capacitor determine the loop stability. The
following applies equally to all linear regulators in the
MAX1513 and MAX1514.
The transconductance amplifier regulates the output
voltage by controlling the pass transistor’s base cur-
rent. The total DC loop gain is approximately:
P
I
V
LOAD MAX
LR
IN MAX
(
LR
(
)_
)_
=
×
(
)
- V
OUT_LR
I
I
R
h
LOAD MAX
DRV
BE
FE MIN
(
(
)
)
×
=
- V
BE
R
R
V
V
V
V
FBN
REF
GOFF
FBN
3
4
×
=
-
-
R
R
V
V
UPPER
LOWER
OUT
FB
×
_
_
=
- 1
C
I
f
OUT CP
LOAD CP
OSC RIPPLE CP
_
_
_
≥
2
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1514ETP+T 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK
MAX1514ETP-T 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK
MAX1515ETG 功能描述:直流/直流開關(guān)調(diào)節(jié)器 RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
MAX1515ETG+ 功能描述:直流/直流開關(guān)調(diào)節(jié)器 3A 1MHz Step-Down DDR Regulator RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
MAX1515ETG+T 功能描述:直流/直流開關(guān)調(diào)節(jié)器 3A 1MHz Step-Down DDR Regulator RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
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