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参数资料
| 型号： | LT1074IT |
| 厂商： | Linear Technology |
| 文件页数： | 11/16页 |
| 文件大小： | 0K |
| 描述： | IC REG MULTI CONFIG ADJ TO220-5 |
| 标准包装： | 50 |
| 类型： | 降压（降压），升压（升压），反相，回扫 |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 2.5 V ~ 50 V |
| 输入电压： | 8 V ~ 45 V |
| 频率 - 开关： | 100kHz |
| 电流 - 输出： | 5A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 通孔 |
| 封装/外壳： | TO-220-5 成形引线 |
| 包装： | 管件 |
| 供应商设备封装： | TO-220-5 |
LT1074/LT1076
PI DESCRIPTIO S
V IN
R FB = ( I SC ? 0 . 44 * )( R L ) ( R L in k ? )
I LIM PIN
The I LIM pin is used to reduce current limit below the
preset value of 6.5A. The equivalent circuit for this pin is
shown in Figure 8.
TO LIMIT
CIRCUIT
320 μ A
from forcing current back into the I LIM pin. To calculate a
value for R FB , first calculate R LIM , the R FB :
0 . 5 * ( R L ? 1 k ? ) ? I SC
*Change 0.44 to 0.16, and 0.5 to 0.18 for LT1076.
Q1
D2
Example: I LIM = 4A, ISC = 1.5A, R LIM = (4)(2k) + 1k = 9k
( 1 . 5 ? 0 . 44 ) ( 9 k ? ) ( ) ?
0 . 5 ( ) ? 1 . 5
R1
8K
D1
D3
6V
4.3V
R FB =
9 k ? 1 k
3 . 8 k
I LIM
LT1047?PD12
Figure 8. I LIM Pin Circuit
LT1074
V OUT
When I LIM is left open, the voltage at Q1 base clamps at 5V
through D2. Internal current limit is determined by the
I LIM
FB
current through Q1. If an external resistor is connected
between I LIM and ground, the voltage at Q1 base can be
R LIM
R FB
D2
1N4148
reduced for lower current limit. The resistor will have a
voltage across it equal to (320 μ A)(R), limited to ≈ 5V when
clamped by D2. Resistance required for a given current
limit is:
R LIM = I LIM (2k ? ) + 1k ? (LT1074)
R LIM = I LIM (5.5k ? ) + 1k ? (LT1076)
As an example, a 3A current limit would require
3A(2k) + 1k = 7k ? for the LT1074. The accuracy of these
formulas is ± 25% for 2A ≤ I LIM ≤ 5A (LT1074) and
7A ≤ I LIM ≤ 1.8A (LT1076), so I LIM should be set at least
25% above the peak switch current required.
Foldback current limiting can be easily implemented by
adding a resistor from the output to the I LIM pin as shown
in Figure 9. This allows full desired current limit (with or
without R LIM ) when the output is regulating, but reduces
current limit under short-circuit conditions. A typical value
for R FB is 5k ? , but this may be adjusted up or down to set
the amount of foldback. D2 prevents the output voltage
LT1074?PD13
Figure 9. Foldback Current Limit
Error Amplifier
The error amplifier in Figure 10 is a single stage design
with added inverters to allow the output to swing above
and below the common mode input voltage. One side of
the amplifier is tied to a trimmed internal reference voltage
of 2.21V. The other input is brought out as the FB (feed-
back) pin. This amplifier has a G M (voltage “in” to current
“out”) transfer function of ≈ 5000 μ mho. Voltage gain is
determined by multiplying G M times the total equivalent
output loading, consisting of the output resistance of Q4
and Q6 in parallel with the series RC external frequency
compensation network. At DC, the external RC is ignored,
and with a parallel output impedance for Q4 and Q6 of
400k ? , voltage gain is ≈ 2000. At frequencies above a few
hertz, voltage gain is determined by the external compen-
sation, R C and C C .
sn1074 1074fds
11
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相关代理商/技术参数 |
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| LT1074IT#06 | 制造商:Linear Technology 功能描述:Step-Down Switching Regulator |
| LT1074IT#06PBF | 功能描述:IC REG MULTI CONFIG ADJ TO220-5 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 |
| LT1074IT#06PBF | 制造商:Linear Technology 功能描述:IC DC-DC CONV 5A 64V TO-22 制造商:Linear Technology 功能描述:IC, DC-DC CONV, 5A, 64V, TO-220-5 |
| LT1074IT#PBF | 功能描述:IC REG MULTI CONFIG ADJ TO220-5 RoHS:否 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 |
| LT1074IT7 | 功能描述:IC REG MULTI CONFIG ADJ TO220-7 RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 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:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
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