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| 型号： | MAX1997ETJ+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 22/31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
Output Capacitor
The output capacitor affects the circuit ’ s stability and
output-voltage ripple. A 15μF ceramic capacitor works
V IN
L
D
V MAIN
well in most 1.5MHz applications. Depending on the
output capacitor chosen, feedback compensation may
be required or desirable to increase the loop phase
LX
R7
R9
D1
margin or increase the loop bandwidth for transient
response. (See the Feedback Compensation section.)
The total output-voltage ripple has three components:
the inductive ripple caused by the capacitor ’ s equivalent
series inductance (ESL), the ohmic ripple due to the
capacitor ’ s equivalent series resistance (ESR), and the
capacitive ripple caused by the charging and discharg-
ing of the output capacitance. Since the ESL is usually
MAX1997
MAX1998
FB
GND
R8
C9
R10
C10
C
R L
V RIPPLE(C) ≈ MAIN ? MAIN IN ?
very small, the inductive ripple can be neglected:
V RIPPLE = V RIPPLE(ESR) + V RIPPLE(C)
V RIPPLE(ESR) ≈ I PEAK R ESR(COUT) , a nd
I ? V -V ?
C OUT ? V MAIN f OSC ?
PGND
Figure 9. External Compensation
The frequency of the dominant pole is:
where I PEAK is the peak inductor current. (See the
Inductor Selection section.) For ceramic capacitors, the
f P_DOMINANT =
1
2 π R L C
output voltage ripple is typically dominated by V RIP-
PLE(C) . The voltage rating and temperature characteris-
where R L is the load resistance and C is the output
capacitance; the frequency of the RHP zero is:
tics of the output capacitor must also be considered.
Feedback Compensation
f Z_RHP = ( 1 ? D ) 2
R L
2 π L
Feedback compensation is not needed for the excellent
stability and fast transient response of Figure 1 ’ s circuit.
where D is the duty cycle and L is the inductance; and
the DC gain is given by:
A DC = 2 0 × log ?
× R L ?
However, lead or lag compensation can be useful to
compensate for layout issues, or optimize the transient
response for various output capacitor or inductor values.
? R 8
? R 7 + R 8
×
( 1 ? D )
R CS
?
?
The loop stability of a current-mode step-up regulator can
be analyzed by using a small-signal model. In continuous
conduction mode, the loop gain transfer function consists
of a DC loop gain, a dominant pole, a right-half-plane
(RHP) zero, and an ESR zero. In the case of ceramic out-
put capacitors, the ESR zero is at very high frequency
and can be ignored. For stable operation, place the domi-
nant pole at a low enough frequency to ensure that the
loop gain reaches unity well before the RHP zero, prefer-
ably below one-third of the RHP zero frequency f Z_RHP .
where R CS is the 20m ? internal equivalent current-
sense resistor, and R7 and R8 are the feedback divider
resistors in Figure 9.
Adding lead compensation (an RC network from V MAIN to
FB) increases the loop bandwidth, which can increase
the speed of response to transients. Too much speed
can destabilize the loop and is not needed or recom-
mended for Figure 1 ’ s components.
Lead compensation adds a zero-pole pair, providing
gain at higher frequencies and increasing loop band-
width. The frequencies of the zero and pole for lead
compensation depend on the feedback divider resistors
and the RC network between V MAIN and FB (Figure 9).
22
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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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