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| 型号： | MAX1997ETJ+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 28/31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
6) To ensure stability, choose CLDO large enough so
V GAMMA
VCOM BUFFER
that the crossover occurs well before the poles and
zero calculated in steps 2 to 5. The poles in steps 3
0.47 μ F
R B
C B
TO TFT LCD
BACKPLANE
and 4 generally occur at several megahertz and
using ceramic capacitors ensures the ESR zero
occurs at several megahertz as well. Placing the
crossover below 500kHz is sufficient to avoid the
amplifier-delay pole and generally works well,
unless unusual component choices or extra capaci-
tances move the other poles or zero below 1MHz.
A capacitor connected between the regulator output and
Figure 11. Optimizing VCOM Buffer Drive Current
the feedback node can improve the transient response
and reduce the noise coupled into the feedback loop
(Figure 1).
V IN
C IN
L
D
V OUT
C OUT
If a low-dropout solution is needed, an external P-channel
MOS pass transistor can be used for REG 1. However, a
PMOS-based linear regulator requires higher output
capacitance to stabilize the loop. The high gate capaci-
tance of the P-channel MOSFET lowers f POLE(CIN) and
can cause instability. A large output capacitor must be
used to reduce the unity-gain bandwidth and ensure that
the pole is well above the unity-gain crossover frequency.
A ceramic capacitor of at least 30μF is recommended for
V IN = 2.7V, V OUT = 2.5V, and I LOAD = 250mA.
GROUND IMPEDANCE
Figure 12. High-Current Loops of Step-Up Regulator
VCOM Buffer
Connect the inverting input FBNB directly to the output
OUTB to configure the buffer as a voltage follower.
Adjust the buffer ’ s output voltage by connecting a volt-
age-divider from the gamma reference V GAMMA to
R13 = R14 ? ? GAMMA ? ? 1 ?
V IN
V N
STEP-UP
REGULATOR
MAX1997
LX
FB
PGND
V P
V MAIN
15V
GND with the center tap connected to the noninverting
input FBPB (Figure 1). Select R14 in the 10k ? to 100k ?
range. Calculate R13 with the following equation:
? ? V ? ?
? ?
? ? V FBPB ? ?
The VCOM buffer is designed to be stable with a
0.47μF capacitor from OUTB to GND. The charge and
discharge currents of the VCOM buffer output can be
optimized by adding resistor R B in series with the LCD
backplane load and a ceramic capacitor C B (1μF or
larger) in parallel with the backplane load (Figure 11).
Start with a 10 ? resistor, then gradually increase the
value of R B , balancing between display quality and
buffer power dissipation. Increasing the value of C B
improves the efficiency of the VCOM buffer.
MAX1998
Figure 13. Operation with Output Voltage >13V Using
Cascoded MOSFET
28
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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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