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参数资料
| 型号： | LT1111IS8#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 6/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK BOOST INV ADJ 8SOIC |
| 标准包装： | 2,500 |
| 类型： | 降压（降压），升压（升压），反相 |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 可调 |
| 输入电压： | 2 V ~ 30 V |
| 频率 - 开关： | 72kHz |
| 电流 - 输出： | 400mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 105°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 |
LT1111
BLOCK D I AGRA S
LT1111
LT1111-5/LT1111-12
V IN
SET
+
–
A2
GAIN BLOCK/
ERROR AMP
A0
I LIM
SW1
V IN
SET
+
–
A2
GAIN BLOCK/
ERROR AMP
A0
I LIM
SW1
1.25V
REFERENCE
GND
FB
+
–
A1
COMPARATOR
OSCILLATOR
DRIVER
SW2
LT1111 ? BD01
1.25V
REFERENCE
R1
+
–
R2
220k
A1
COMPARATOR
SENSE
OSCILLATOR
DRIVER
LT1111-5: R1 = 73.5k
LT1111-12: R1 = 25.5k
SW2
OPERATIO
GND
LT1111 ? BD02
The LT1111 is a gated oscillator switcher. This type
architecture has very low supply current because the
switch is cycled when the feedback pin voltage drops
below the reference voltage. Circuit operation can best be
understood by referring to the LT1111 block diagram.
Comparator A1 compares the feedback (FB) pin voltage
with the 1.25V reference signal. When FB drops below
1.25V, A1 switches on the 72kHz oscillator. The driver
amplifier boosts the signal level to drive the output NPN
power switch. The switch cycling action raises the output
voltage and FB pin voltage. When the FB voltage is suffi-
cient to trip A1, the oscillator is gated off. A small amount
of hysteresis built into A1 ensures loop stability without
external frequency compensation. When the comparator
output is low, the oscillator and all high current circuitry is
turned off, lowering device quiescent current to just 300 μ A.
The oscillator is set internally for 7 μ s ON time and 7 μ s OFF
time, optimizing the device for circuits where V OUT and V IN
differ by roughly a factor of 2. Examples include a 3V to 5V
step-up converter or a 9V to 5V step-down converter.
Gain block A2 can serve as a low-battery detector. The
negative input of A2 is the 1.25V reference. A resistor
divider from V IN to GND, with the mid-point connected to
the SET pin provides the trip voltage in a low-battery
detector application. AO can sink 300 μ A (use a 22k
resistor pull-up to 5V).
A resistor connected between the I LIM pin and V IN sets
maximum switch current. When the switch current ex-
ceeds the set value, the switch cycle is prematurely
terminated. If current limit is not used, I LIM should be tied
directly to V IN . Propagation delay through the current limit
circuitry is approximately 1 μ s.
In step-up mode the switch emitter (SW2) is connected to
ground and the switch collector (SW1) drives the induc-
tor; in step-down mode the collector is connected to V IN
and the emitter drives the inductor.
The LT1111-5 and LT1111-12 are functionally identical to
the LT1111. The -5 and -12 versions have on-chip voltage
setting resistors for fixed 5V or 12V outputs. Pin 8 on the
fixed versions should be connected to the output. No
external resistors are needed.
1111fd
6
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1111M | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower DC/DC Converter Adjustable and Fixed 5V, 12V |
| LT1111MJ8 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower DC/DC Converter Adjustable and Fixed 5V, 12V |
| LT1111MJ8-12 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower DC/DC Converter Adjustable and Fixed 5V, 12V |
| LT1111MJ8-5 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower DC/DC Converter Adjustable and Fixed 5V, 12V |
| LT1112 | 制造商:LINEAR 制造商全称:LINEAR 功能描述:Dual/Quad Low Power Precision, Picoamp Input Op Amps |
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