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参数资料
| 型号： | MAX1518BETJ+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 22/25页 |
| 文件大小： | 0K |
| 描述： | IC DC-DC CONV TFT-LCD 32-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 60 |
| 应用： | 转换器，TFT，LCD |
| 输入电压： | 2.6 V ~ 6.5 V |
| 输出数： | 1 |
| 输出电压： | 2.6 V ~ 13 V |
| 工作温度： | -40°C ~ 100°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 |
TFT-LCD DC-DC Converter with
Operational Amplifiers
? I BIAS × h FE ? ?
A V _ LR ? ? V T ? × ? 1 + ? I ? ? × V REF
f POLE _ IN =
f POLE _ IN = T
The transconductance amplifier regulates the output
voltage by controlling the pass transistor’s base cur-
rent. The total DC loop gain is approximately:
? 10 ? ?
? ?
? ? LOAD _ LR ? ?
where V T is 26mV at room temperature, and I BIAS is the
current through the base-to-emitter resistor (R BE ). For
the MAX1518B, the bias currents for both the gate-on
and gate-off linear-regulator controllers are 0.1mA.
Therefore, the base-to-emitter resistor for both linear
regulators should be chosen to set 0.1mA bias current:
g m is the transconductance of the pass transistor,
and f T is the transition frequency. Both parameters
can be found in the transistor’s data sheet. Because
R BE is much greater than R IN , the above equation
can be simplified:
1
2 π × C IN × R IN
Substituting for C IN and R IN yields:
f
h FE
= ≈ 6 . 8 k ?
R BE =
V BE
0 . 1 mA
0 . 7 V
0 . 1 mA
4) Next, calculate the pole set by the linear regula-
tor ’s feedback resistance and the capacitance
The output capacitor and the load resistance create the
dominant pole in the system. However, the internal
amplifier delay, pass transistor’s input capacitance,
between FB_ and AGND (including stray capaci-
tance):
and the stray capacitance at the feedback node create
additional poles in the system, and the output capaci-
tor’s ESR generates a zero. For proper operation, use
f POLE _ FB =
1
2 π × C FB × ( R UPPER || R LOWER )
f POLE _ LR =
f POLE _ ESR =
the following equations to verify the linear regulator is
properly compensated:
1) First, determine the dominant pole set by the linear
regulator’s output capacitor and the load resistor:
I LOAD ( MAX )_ LR
2 π × C OUT _ LR × V OUT _ LR
The unity-gain crossover of the linear regulator is:
f CROSSOVER = A V_LR ? f POLE_LR
2) The pole created by the internal amplifier delay is
approximately 1MHz:
f POLE_AMP = 1MHz
3) Next, calculate the pole set by the transistor’s
input capacitance, the transistor’s input resistance,
and the base-to-emitter pullup resistor:
where C FB is the capacitance between FB_ and
AGND, R UPPER is the upper resistor of the linear
regulator ’s feedback divider, and R LOWER is the
lower resistor of the divider.
5) Next, calculate the zero caused by the output
capacitor’s ESR:
1
2 π × C OUT _ LR × R ESR
where R ESR is the equivalent series resistance of
C OUT_LR .
To ensure stability, choose C OUT_LR large enough so
the crossover occurs well before the poles and zero
calculated in steps 2 to 5. The poles in steps 3 and 4
generally occur at several megahertz, and using
ceramic capacitors ensures the ESR zero occurs at
f POLE _ IN =
1
2 π × C IN × ( R BE || R IN )
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 capacitances move one of the other
poles or the zero below 1MHz.
where C IN =
g m
2 π f T
, R IN =
h FE
g m
,
22
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1518BETJ+ | 功能描述:LCD 驱动器 TFT-LCD DC-DC Conv w/Op Amps 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 |
| MAX1518BETJ+T | 功能描述:LCD 驱动器 TFT-LCD DC-DC Conv w/Op Amps 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 |
| MAX1518ETJ | 功能描述:LCD 驱动器 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 |
| MAX1518ETJ+ | 功能描述:LCD 驱动器 TFT-LCD DC-DC Conv w/Op Amps 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 |
| MAX1518ETJ+T | 功能描述:LCD 驱动器 TFT-LCD DC-DC Conv w/Op Amps 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 |
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