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参数资料
| 型号： | MAX1997ETJ+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 24/31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
( )
V IN IN L(MAX) DS(MAX) ×
×
= V -I
× R
V IN
R2
P1
R DS(ON)
R4
If the comparator and resistors are ideal, the threshold
is at the current where both inputs are equal:
R 3 R 5
R 2 + R 3 R 4 + R 5
I L(MAX) is the average inductor current at maximum load
OCP
condition and minimum input voltage, and is given by:
100pF
OCN
I L(MAX) =
V OUT
η × V IN(MIN)
× I LOAD(MAX)
R3
R5
OC COMP
where η is the efficiency of the main step-up regulator.
If the step-up regulator ’ s minimum input voltage is 2.7V,
the output voltage is 9V, and the maximum load current is
I L(MAX) =
× 0.3A = 1 . 25A
Figure 10. Setting the Overcurrent Threshold
Input P-Channel MOSFET
Select the input P-channel MOSFET based on current
rating, voltage rating, gate threshold, and on-resis-
tance. The MOSFET must be able to handle the peak
input current (see the Inductor Selection section). The
drain-to-source voltage rating of the input MOSFET
should be higher than the maximum input voltage.
Because the MOSFET conducts the full input current,
its on-resistance should be low enough for good effi-
ciency. Use a logic-level or low-threshold MOSFET to
ensure that the switch is fully enhanced at the lowest
input voltage.
Setting the Input Overcurrent Threshold
The high-side comparator of the MAX1997/MAX1998
provides input overcurrent protection when used in con-
junction with an external P-channel MOSFET P1. The
accuracy of the overcurrent threshold is affected by
many factors, including comparator offset, resistor toler-
ance, input voltage range, and variations in MOSFET
R DS(ON) . The input overcurrent comparator is only
intended to protect against catastrophic failures. This
function is similar to an input fuse.
To minimize the impact of the comparator ’ s input offset
0.3A. Assuming 80% efficiency, the maximum average
inductor current is:
9V
0.8 × 2.7V
R DS(MAX) is the maximum on-state drain-to-source
resistance of P1. The maximum R DS(ON) at +25 ° C can
be found in the MOSFET manufacturer ’ s data sheet, but
that number does not include the MOSFET ’ s tempera-
ture coefficient. Since the resistance temperature coef-
ficient is 0.5%/ ° C, R DS(MAX) can be calculated with the
following equation:
R DS(MAX) = R DS_25C ? [1 + 0.005 ? (T J - 25)]
where T J is the actual MOSFET junction temperature in
normal operation due to ambient temperature and self-
heating caused by power dissipation. As an example,
consider the Fairchild FDN304P, which has a maximum
R DS(ON) at room temperature of 70m ? . If the junction
temperature is +100 ° C, the maximum on-state resis-
tance over temperature is:
R DS(MAX) = 70m ? [1 + 0.005 ? (100 - 25)] = 100m ?
For given R2 and R3 values, the ideal ratio of R4/R5
can be determined:
on the current-sense accuracy, the sense voltage
should be close to the upper limit of the comparator ’ s
common-mode range (same as the operating range),
R 4
R 5
=
R 2 + R 3
R 3
×
V IN
V IN - I PEAK(MAX) × R DS(MAX)
- 1
which extends up to 80% of the input voltage. The
resistive voltage divider R4/R5, combined with the on-
state resistance of P1, sets the overcurrent threshold.
The center of R4/R5 is connected to the inverting input
(OCN) as shown in Figure 10.
24
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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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