参数资料
| 型号： | LT337AT |
| 厂商： | Linear Technology |
| 文件页数： | 7/12页 |
| 文件大小： | 0K |
| 描述： | IC REG LDO NEG ADJ TO220-3 |
| 标准包装： | 50 |
| 稳压器拓扑结构： | 负，可调式 |
| 输出电压： | -1.2 V ~ -37 V |
| 稳压器数量： | 1 |
| 电流 - 限制（最小）： | 1.5A |
| 工作温度： | 0°C ~ 125°C |
| 安装类型： | 通孔 |
| 封装/外壳： | TO-220-3 |
| 供应商设备封装： | TO-220-3 |
| 包装： | 管件 |
LT137A/LM137
LT337A/LM337
APPLICATIONS INFORMATION
+ I ADJ ( R 2 )
V OUT REF ? 1 +
= V
V OUT REF
=
= 696 . 4 Ω
V REF
+ 65 μ A
+ I ADJ
Output Voltage
The output voltage is determined by two external resis-
tors, R1 and R2 (see Figure 1). The exact formula for the
output voltage is:
? R2 ?
?
? R 1 ?
Where: V REF = Reference Voltage, I ADJ = Adjustment Pin
Current. In most applications, the second term is small
enough to be ignored, typically about 0.5% of V OUT . In
more critical applications, the exact formula should be
used, with I ADJ equal to 65μA. Solving for R2 yields:
EXAMPLES:
1. A precision 10V regulator to supply up to 1A load
current.
a. Select R1 = 100Ω to minimize effect of I ADJ
b. Calculate R2 =
– V 10 V – 1 . 25 V
1.25 V
R 1 100 Ω
Use R2 = 698Ω
2. A 15V regulator to run off batteries and supply
V OUT REF
+ I ADJ
R 2 =
V REF
R 1
– V
50mA. V IN MAX = 25V
a. To minimize battery drain, select R1 as high as
possible
Smaller values of R1 and R2 will reduce the in?uence
of I ADJ on the output voltage, but the no-load current
R 1 =
1.25 V
3 mA
= 417 Ω , use 402 Ω , 1%
drain on the regulator will be increased. Typical values
for R1 are between 100Ω and 300Ω, giving 12.5mA and
4.2mA no-load current respectively. There is an additional
consideration in selecting R1, the minimum load current
b. The high value for R1 will exaggerate the error due
to I ADJ , so the exact formula to calculate R2 should
be used.
V OUT REF
+ I ADJ
+ 6 5 μA
speci?cationoftheregulator.Theoperatingcurrentofthe
LT137A ?ows from input to output. If this current is not
absorbed by the load, the output of the regulator will rise
above the regulated value. The current drawn by R1 and
R 2 =
V REF
R 1
– V
=
15 V – 1 . 25 V
1. 25 V
402 Ω
= 4331 Ω
R2 is normally high enough to absorb the current, but
care must be taken in no-load situations where R1 and
R2 have high values.
The maximum value for the operating current, which must
be absorbed, is 5mA for the LT137A. If input-output volt-
age differential is less than 10V, the operating current that
must be absorbed drops to 3mA.
Use R2 = 4320Ω
Capacitors and Protection Diodes
An output capacitor, C3, is required to provide proper fre-
quency compensation of the regulator feedback loop. A 1μF
or larger solid tantalum capacitor is generally suf?cient for
this purpose if the 1MHz impedance of the capacitor is 2Ω
or less. High Q capacitors, such as Mylar, are not recom-
+
C2
+
C1
10μF
I ADJ
R2
+
C3
mended because they tend to reduce the phase margin at
light load currents. Aluminum electrolytic capacitors may
also be used, but the minimum value should be 10μF to
5μF
1μF
ensure a low impedance at 1MHz. The output capacitor
ADJ
V REF
R1
should be located within a few inches of the regulator to
–V IN
V IN
LT137A V OUT
–V OUT
keep lead impedance to a minimum. The following caution
should be noted: if the output voltage is greater than 6V
137A F01
Figure 1
and an output capacitor greater than 20μF has been used,
it is possible to damage the regulator if the input voltage
137afb
7
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT337AT#PBF | 功能描述:IC REG LDO NEG ADJ TO220-3 RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:1 系列:- 稳压器拓扑结构:正，固定式 输出电压:8V 输入电压:10.5 V ~ 23 V 电压 - 压降（标准）:1.7V @ 40mA 稳压器数量:1 电流 - 输出:100mA（最小值） 电流 - 限制（最小）:- 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） 供应商设备封装:8-SOIC 包装:剪切带 (CT) 产品目录页面:1075 (CN2011-ZH PDF) 其它名称:296-24390-1 |
| LT337AT#PBF | 制造商:Linear Technology 功能描述:IC NEGATIVE ADJ REG -1.2V TO 7V TO-220 制造商:Linear Technology 功能描述:IC, NEGATIVE ADJ REG, -1.2V TO 7V TO-220 |
| LT337ATPBF | 制造商:Linear Technology 功能描述:Negative Adjustable Regulator 1.5A TO220 |
| LT337BC | 制造商:EDSYN 功能描述: |
| LT337H | 制造商:LINER 制造商全称:Linear Technology 功能描述:Negative Adjustable Regulator |
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