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| 型号： | MAX8753ETI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 16/20页 |
| 文件大小： | 0K |
| 描述： | IC DC-DC CONV TFT LCD 28TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 应用： | 转换器，TFT，LCD |
| 输入电压： | 2.6 V ~ 5.5 V |
| 输出数： | 4 |
| 输出电压： | 2.6 V ~ 13 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 供应商设备封装： | 28-TQFN-EP（5x5） |
| 包装： | 带卷 (TR) |
TFT LCD DC-DC Converter with
Integrated Charge Pumps
? 3 . 3 V ? ?
? ? 0 . 80 ?
9 V ? 3 . 3 V
? 9 V ? ? 0 . 19 A × 1 MHz ? ? ? 0 . 45 ?
plus the contributions from the positive and negative
charge pumps:
I MAIN ( EFF ) = I MAIN ( MAX ) + n NEG × I NEG + 3 × I POS
where I MAIN(MAX) is the maximum output current, n NEG
2
L = ? ? ? ? ? ≈ 6 . 8 μ H
Using the circuit ’ s minimum input voltage (2.6V) and
estimating efficiency of 70% at that operating point:
is the number of negative charge-pump stages, I NEG is
the negative charge-pump output current, and I POS is
the positive charge-pump output current.
I IN ( DC , MAX ) =
0.19 A × 9 V
2 . 6 V × 0 . 7
≈ 0 . 94 A
Calculate the approximate inductor value using the typ-
2 . 6 V × ( 9 V ? 2 . 6 V )
I RIPPLE = = 0 . 27 A
ical input voltage (V IN ), the maximum output current
(I MAIN(MAX) ), the expected efficiency ( η TYP ) taken from
an appropriate curve in the Typical Operating
Characteristics , and an estimate of LIR based on the
above discussion:
The ripple current and the peak current are:
6 . 8 μ H × 9 V × 1 MHz
? V IN ? ?
? ? η
V MAIN ? V IN
TYP ?
? ? I
L = ? ? ? ?
2
? V MAIN ? ? MAIN ( EFF ) × f OSC ? ? LIR ?
I PEAK = 0 . 94 A +
0.27 A
2
= 1 . 08 A
I MAIN ( EFF ) × V MAIN
V IN ( MIN ) × η MIN
V RIPPLE ( C ) ≈ MAIN ? MAIN IN ? and
Choose an available inductor value from an appropriate
inductor family. Calculate the maximum DC input cur-
rent at the minimum input voltage V IN(MIN) using con-
servation of energy and the expected efficiency at that
operating point ( η MIN ) taken from an appropriate curve
in the Typical Operating Characteristics :
,
I IN ( DCMAX ) =
Calculate the ripple current at that operating point and
Output Capacitor Selection
The total output-voltage ripple has two components: the
capacitive ripple caused by the charging and discharg-
ing of the output capacitance, and the ohmic ripple due
to the capacitor ’ s equivalent series resistance (ESR):
V RIPPLE = V RIPPLE ( C ) + V RIPPLE ( ESR )
I ? V ? V ?
C OUT ? V MAIN f OSC ?
V IN ( MIN ) × ( V MAIN IN ( MIN )
L × V MAIN × f OSC
I PEAK IN ( DCMAX ) + RIPPLE
= I
2
the peak current required for the inductor:
? V
I RIPPLE =
I
,
)
V RIPPLE ( ESR ) ≈ I PEAK R ESR ( COUT )
where I PEAK is the peak inductor current (see the
Inductor Selection section). For ceramic capacitors,
the output voltage ripple is typically dominated by
V RIPPLE(C) . The voltage rating and temperature charac-
teristics of the output capacitor must also be considered.
Input Capacitor Selection
The inductor ’ s saturation current rating and the
MAX8753 ’ s LX current limit (I LX(MAX) ) should exceed
I PEAK and the inductor ’ s DC current rating should
exceed I IN(DC,MAX) . For good efficiency, choose an
inductor with less than 0.1 ? series resistance.
Considering the typical operating circuit, the maximum
load current (I MAIN(MAX) ) is 140mA with a 9V output
and a typical input voltage of 3.3V:
I MAIN ( EFF ) = 140 mA + 2 × 10 mA + 3 × 10 mA = 190 mA
Choosing an LIR of 0.45 and estimating efficiency of
80% at this operating point:
The input capacitor (C IN ) (see Figure 1) reduces the
current peaks drawn from the input supply and reduces
noise injection into the IC. A 10μF ceramic capacitor is
used in the typical operating circuit (Figure 1) because
of the high source impedance seen in typical lab
setups. Actual applications usually have much lower
source impedance since the step-up regulator often
runs directly from the output of another regulated sup-
ply. Typically, C IN can be reduced below the values
used in the typical operating circuit. Ensure a low noise
supply at IN by using adequate C IN .
16
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| MAX8753EVKIT | 功能描述:电源管理IC开发工具 MAX8753 Eval Kit RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MAX8756ETI+ | 功能描述:电流和电力监控器、调节器 Interleaved Dual Power-Supply Ctlr RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX8756ETI+T | 功能描述:电流和电力监控器、调节器 Interleaved Dual Power-Supply Ctlr RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX8757ETG+ | 制造商:Maxim Integrated Products 功能描述:INTERLEAVED HI-EFF AND DUAL PS CNTRLR 24TQFN EP - Rail/Tube |
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