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| 型号： | MAX1997ETJ+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 27/31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： | 2,500 |
| 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： | 带卷 (TR) |
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Quintuple/Triple-Output TFT LCD Power Supplies
with Fault Protection and VCOM Buffer
Stability Requirements
The MAX1997/MAX1998 linear-regulator controllers use
an internal transconductance amplifier to drive an
external pass transistor. The transconductance amplifi-
3) Next, calculate the pole set by the transistor ’ s input
capacitance, the transistor ’ s input resistance, and
the base-to-emitter pullup resistor:
er, the pass transistor, the base-emitter resistor, and
the output capacitor determine the loop stability.
f POLE(CIN) =
1
2 π C I N ( R BE
II R IN )
The transconductance amplifier regulates the output
? V T ? ? ?
? LOAD ? ? ?
f POLE(CIN) ≈
C IN =
R I N = R π = FE
voltage by controlling the pass transistor ’ s base cur-
rent. The total DC loop gain is approximately:
? 4 ? ? ? I BIAS h FE ? ?
A V(LDO) = ? ? ? 1 + ? I ? ? V REF
where V T is 26mV at room temperature, h FE is the pass
transistor ’ s DC current gain, and I BIAS is the current
through the base-to-emitter resistor (R BE ). Each of the
four linear-regulator controllers is designed for a differ-
ent maximum output current so they have different out-
put drive currents and different bias currents (I BIAS ).
Each controller ’ s bias current can be found in the
Electrical Characteristics . The current listed in the
Conditions column for the FB_ Regulation Voltage
specification is the individual controller ’ s bias current.
Because R BE is much greater than R IN , the above
equation can be simplified:
1
2 π C I N R I N
g m
2 π f T
h
g m
where g m is the transconductance of the pass tran-
sistor, and f T is the transition frequency. Both para-
meters can be found in the transistor ’ s data sheet.
Therefore, the equation can be further simplified:
The base-to-emitter resistor for each controller should
be chosen to set the correct I BIAS :
f POLE(CIN) =
f T
h FE
R BE =
V BE
I BIAS
4) Next, calculate the pole set by the linear regulator ’ s
feedback resistance and the capacitance between
f POLE ( FB )_ P =
The output capacitor and the load resistance create the
dominant pole in the system. However, the internal
amplifier delay, the pass transistor ’ s input capacitance,
and the stray capacitance at the feedback node create
FB_ and GND (approximately 5pF including stray
capacitance):
1
2 π C FB ( R 19 || R 20 )
additional poles in the system, and the output capacitor ’ s
ESR generates a zero. For proper operation, use the
following steps to ensure the linear regulator stability:
1) First, calculate the dominant pole set by the linear
regulator ’ s output capacitor and the load resistor:
f POLE ( FB )_ 1 =
f POLE ( FB )_ 2 =
1
2 π C FB ( R 88 || R 99 )
1
2 π C FB ( R 11 || R 12 )
f POLE(LDO) =
1
2 π C LDO R LOAD
where C LDO is the output capacitance of the LDO
and
f POLE ( FB )_ N =
1
2 π C FB ( R 16 || R 17 )
and R LOAD is the load resistance corresponding to
the maximum load current.
The unity gain crossover of the linear regulator is:
5) Next, calculate the zero caused by the output
capacitor ’ s ESR:
f CROSSOVER = A V(LDO) f POLE(LDO)
2) The pole caused by the internal amplifier delay is at
f ESR _ ZERO =
1
2 π C LDO R ESR
about 1MHz:
f POLE(AMP) ? 1MHz
where R ESR is the equivalent series resistance of
C LDO .
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
| MAX19985AETX+ | 功能描述:上下转换器 High-Gain 700MHz to 1GHz Downconv 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 |
| MAX19985AETX+T | 功能描述:上下转换器 High-Gain 700MHz to 1GHz Downconv 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 |
| MAX19985ETX+ | 功能描述:上下转换器 Dual, SiGe, .7-1GHz Downconversion Mixer 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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