参数资料
型号: LT1374CS8#TRPBF
厂商: Linear Technology
文件页数: 26/32页
文件大小: 0K
描述: IC REG BUCK ADJ 4.5A 8SOIC
标准包装: 2,500
类型: 降压(降压)
输出类型: 可调式
输出数: 1
输出电压: 2.42 V ~ 21.5 V
输入电压: 5 V ~ 25 V
PWM 型: 电流模式
频率 - 开关: 500kHz
电流 - 输出: 4.5A
同步整流器:
工作温度: 0°C ~ 125°C
安装类型: 表面贴装
封装/外壳: 8-SOIC(0.154",3.90mm 宽)
包装: 带卷 (TR)
供应商设备封装: 8-SOIC
LT1374
APPLICATIO N S I N FOR M ATIO N
With the conditions above:
This duty cycle is close enough to 50% that I P can be
assumed to be 4.5A.
OUTPUT DIVIDER
If the adjustable part is used, the resistor connected to
V OUT (R2) should be set to approximately 5k. R1 is
calculated from:
INDUCTOR VALUE
Unlike buck converters, positive-to-negative converters
cannot use large inductor values to reduce output ripple
voltage. At 500kHz, values larger than 25 μ H make almost
no change in output ripple. The graph in Figure 16 shows
peak-to-peak output ripple voltage for a 5V to – 5V con-
verter versus inductor value. The criteria for choosing the
inductor is therefore typically based on ensuring that peak
switch  current  rating  is  not  exceeded.  This  gives  the
250
5V TO – 5V CONVERTER
lowest value of inductance that can be used, but in some
cases (lower output load currents) it may give a value that
creates unnecessarily high output ripple voltage. A com-
promise value is often chosen that reduces output ripple.
As you can see from the graph, large inductors will not
give arbitrarily low ripple, but small inductors can give
high ripple.
The difficulty in calculating the minimum inductor size
needed is that you must first know whether the switcher
will be in continuous or discontinuous mode at the critical
point where switch current is 4.5A. The first step is to use
the following formula to calculate the load current where
the switcher must use continuous mode. If your load
current is less than this, use the discontinuous mode
formula to calculate minimum inductor needed. If load
current is higher, use the continuous mode formula.
Output current where continuous mode is needed:
Minimum inductor discontinuous mode:
200
OUTPUT CAPACITOR’S
ESR = 0.05 ?
Minimum inductor continuous mode:
150
I LOAD = 1A
100
50
0
I LOAD = 0.25A
For the example above, with maximum load current of 1A:
0
5
10
15
20
INDUCTOR SIZE ( μ H)
1374 F16
Figure 16. Ripple Voltage on Positive-to-Negative Converter
1374fd
26
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相关代理商/技术参数
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LT1374CT7#PBF 功能描述:IC REG BUCK ADJ 4.5A TO220-7 RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:250 系列:- 类型:降压(降压) 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON(1.45x1) 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2
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LT1374HV 制造商:LINER 制造商全称:Linear Technology 功能描述:4.5A, 500kHz Step-Down Switching Regulator