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| 型号： | LT1076HVCT7-5#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 9/16页 |
| 文件大小： | 0K |
| 描述： | IC REG MULTI CONFIG 5V TO220-7 |
| 标准包装： | 50 |
| 类型： | 降压（降压），升压（升压），反相，回扫 |
| 输出类型： | 固定 |
| 输出数： | 1 |
| 输出电压： | 5V |
| 输入电压： | 8 V ~ 60 V |
| 频率 - 开关： | 100kHz |
| 电流 - 输出： | 2A |
| 同步整流器： | 无 |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 通孔 |
| 封装/外壳： | TO-220-7 成形引线 |
| 包装： | 管件 |
| 供应商设备封装： | TO-220-7 |
LT1074/LT1076
PI DESCRIPTIO S
current is well controlled even when switch duty cycle
must be extremely low. Theoretical switch “on” time for a
buck converter in continuous mode is:
SHUTDOWN PIN
The shutdown pin is used for undervoltage lockout, micro-
power shutdown, soft-start, delayed start, or as a general
t ON =
V OUT + V D
V IN ? f
purpose on/off control of the regulator output. It controls
switching action by pulling the I LIM pin low, which forces
the switch to a continuous “off” state. Full micropower
V D = Catch diode forward voltage ( ≈ 0.5V)
f = Switching frequency
At f = 100kHz, t ON must drop to 0.2 μ s when V IN = 25V
and the output is shorted (V OUT = 0V). In current limit,
the LT1074 can reduce t ON to a minimum value of
≈ 0.6 μ s, much too long to control current correctly for
V OUT = 0. To correct this problem, switching frequency
is lowered from 100kHz to 20kHz as the FB pin drops
from 1.3V to 0.5V. This is accomplished by the circuitry
TO
OSCILLATOR
V OUT
shutdown is initiated when the shutdown pin drops below
0.3V.
The V/I characteristics of the shutdown pin are shown in
Figure 4. For voltages between 2.5V and ≈ V IN , a current of
10 μ A flows out of the shutdown pin. This current in-
creases to ≈ 25 μ A as the shutdown pin moves through the
2.35V threshold. The current increases further to ≈ 30 μ A at
the 0.3V threshold, then drops to ≈ 15 μ A as the shutdown
voltage fall below 0.3V. The 10 μ A current source is in-
cluded to pull the shutdown pin to its high or default state
when left open. It also provides a convenient pull-up for
delayed start applications with a capacitor on the shut-
down pin.
+
+2V
2.21V
Q1
R3
R1
When activated, the typical collector current of Q1 in
Figure 5, is ≈ 2mA. A soft-start capacitor on the I LIM pin will
V C
ERROR
AMPLIFIER
–
3k
FB
R2
EXTERNAL
DIVIDER
delay regulator shutdown in response to C1, by
≈ (5V)(C LIM )/2mA. Soft-start after full micropower shut-
down is ensured by coupling C2 to Q1.
2.21k
0
Figure 3. Frequency Shifting
LT1074?PD03
–5
–10
T j = 25 ° C
CURRENT FLOWS OUT
OF SHUTDOWN PIN
shown in Figure 3.
Q1 is off when the output is regulating (V FB = 2.21V). As
the output is pulled down by an overload, V FB will eventu-
ally reach 1.3V, turning on Q1. As the output continues to
drop, Q1 current increases proportionately and lowers the
–15
–20
–25
–30
–35
SHUTDOWN
THRESHOLD
frequency of the oscillator. Frequency shifting starts when
the output is ≈ 60% of normal value, and is down to its
minimum value of ? 20kHz when the output is ? 20% of
–40
0
0.5
1.0
1.5 2.0 2.5
VOLTAGE (V)
3.0
3.5 4.0
LT1074?PC05
normal value. The rate at which frequency is shifted is
determined by both the internal 3k resistor R3 and the
Figure 4. Shutdown Pin Characteristics
external divider resistors. For this reason, R2 should not
be increased to more than 4k ? , if the LT1074 will be
subjected to the simultaneous conditions of high input
voltage and output short-circuit.
sn1074 1074fds
9
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1076HVCTPBF | 制造商:Linear Technology 功能描述:DC-DC Converter Step-Down 60V TO220-5 |
| LT1076HVIR | 功能描述:IC REG MULTI CONFIG ADJ 2A 7DD 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 |
| LT1076HVIR#PBF | 功能描述:IC REG MULTI CONFIG ADJ 2A 7DD RoHS:是 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 |
| LT1076HVIR#PBF | 制造商:Linear Technology 功能描述:IC, DC-DC CONV, BUCK, 100KHZ, 2.6A, TO-2 |
| LT1076HVIR#TR | 功能描述:IC REG MULTI CONFIG ADJ 2A 7DD 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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