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参数资料
| 型号： | MAX1997ETJ+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 26/31页 |
| 文件大小： | 0K |
| 描述： | IC PWR SUPPLY TFT LCD 32TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 60 |
| 应用： | 控制器，TFT LCD |
| 输入电压： | 2.7 V ~ 5.5 V |
| 输出数： | 5 |
| 输出电压： | 2.7 V ~ 13 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 供应商设备封装： | 32-TQFN-EP（5x5） |
| 包装： | 管件 |
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Quintuple/Triple-Output TFT LCD Power Supplies
with Fault Protection and VCOM Buffer
I LOAD(MAX) = ? I DRV ? BE ? β MIN
Flying Capacitors
Increasing the flying capacitor (C X ) value 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 limit the source impedance. A
0.1μF ceramic capacitor works well in most low-current
applications. The flying capacitor ’ s voltage rating must
exceed the following:
V CX > N ? V MAIN
where N is the stage number in which the flying capaci-
tor appears, and V MAIN is the main output voltage. For
example, the two-stage positive charge pump in the
typical application circuit (Figure 1) where V MAIN = 9V
contains two flying capacitors. The flying capacitor in
the first stage (C25) requires a voltage rating greater
than 9V. The flying capacitor in the second stage (C24)
requires a voltage rating greater than 18V.
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:
Calculate R19 with the following equation:
R19 = R20 [(V G_ON / V FBP ) - 1]
where V FBP = 1.25V.
The output voltages of linear regulators REG 1 and
REG 2 can be similarly adjusted.
Adjust the negative linear-regulator (REG N) output
voltage by connecting a resistive voltage-divider from
V G_OFF to REF with the center tap connected to FBN
(Figure 1). Select R17 in the range of 10k ? to 30k ? .
Calculate R16 with the following equation:
R16 = R17 [(V FBN - V G_OFF ) / (V REF - V FBN )]
where V FBN = 125mV, V REF = 1.25V. REF can source
up to 75μA, using a resistor greater than 17k ? for R17
leaves at least 10μA for other uses.
Pass Transistor Selection
The pass transistor must meet specifications for current
gain ( β ), input capacitance, collector-emitter saturation
voltage, and power dissipation. The transistor ’ s current
gain limits the guaranteed maximum output current to:
? V ?
? R BE ?
C OUT ≥
I LOAD
2f OSC V RIPPLE
where I DRV is the minimum guaranteed base drive cur-
rent, V BE is the base-to-emitter voltage of the transistor,
and R BE is the pullup resistor connected between the
where V RIPPLE is the peak-to-peak value of the output
ripple.
Charge-Pump Rectifier Diodes
Use Schottky diodes with a current rating equal to or
greater than two times the average charge-pump input
current. If the loaded charge-pump output voltage is
greater than required, some or all of the Schottky
diodes can be replaced with low-cost silicon switching
diodes with an equivalent current rating. The charge-
pump input current is:
I CP _ IN = I CP _ OUT ? N
where N is the number of charge-pump stages.
Linear-Regulator Controllers
Output Voltage Selection
Adjust the positive linear-regulator (REG P) output volt-
age by connecting a resistive voltage-divider from
V G_ON to GND with the center tap connected to FBP
(Figure 1). Select R20 in the range of 10k ? to 30k ? .
transistor ’ s base and emitter. Furthermore, the transis-
tor ’ 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. The transistor ’ s input capacitance and
input resistance also create a second pole, which
could be low enough to make the output unstable when
heavily loaded.
The transistor ’ s saturation voltage at the maximum out-
put current determines the minimum input-to-output
voltage differential that the linear regulator supports.
Alternatively, the package ’ s power dissipation could
limit the usable maximum input-to-output voltage differ-
ential. The maximum power dissipation capability of the
transistor ’ s package and mounting must exceed the
actual power dissipation in the device. The power dissi-
pation equals the maximum load current times the max-
imum input-to-output voltage differential:
P = I LOAD(MAX) (V LDOIN - V LDOOUT ) = I LOAD(MAX) V CE
26
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1997ETJ+ | 功能描述:其他电源管理 Quint/Triple-Out TFT LCD Power Supply RoHS:否 制造商:Texas Instruments 输出电压范围: 输出电流:4 mA 输入电压范围:3 V to 3.6 V 输入电流: 功率耗散: 工作温度范围:- 40 C to + 110 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-48 封装:Reel |
| MAX1997ETJ+T | 功能描述:LCD 驱动器 Quint/Triple-Out TFT LCD Power Supply RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube |
| MAX1997ETJ-T | 功能描述:其他电源管理 RoHS:否 制造商:Texas Instruments 输出电压范围: 输出电流:4 mA 输入电压范围:3 V to 3.6 V 输入电流: 功率耗散: 工作温度范围:- 40 C to + 110 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-48 封装:Reel |
| MAX1997EVKIT | 制造商:Maxim Integrated Products 功能描述:QUINTUPLE/TRIPLE OUTPUT TFT LCD POWER SUPPLIE - Bulk |
| MAX19983A | 功能描述:上下转换器 RoHS:否 制造商:Texas Instruments 产品:Down Converters 射频:52 MHz to 78 MHz 中频:300 MHz LO频率: 功率增益: P1dB: 工作电源电压:1.8 V, 3.3 V 工作电源电流:120 mA 最大功率耗散:1 W 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PQFP-128 |
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