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參數(shù)資料
| 型號： | LT1105CS |
| 英文描述： | Current-Mode SMPS Controller |
| 中文描述： | 電流模式開關電源控制器 |
| 文件頁數(shù)： | 6/16頁 |
| 文件大?。?/td> | 206K |
| 代理商： | LT1105CS |
6
LT1107
1107fa
W
IAGRA
BLOCK
S
OPERATIO
The LT1107 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 LT1107 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 63kHz 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 11
μ
s ON time and 5
μ
s
OFF time in step-up mode, optimizing the device for
converters where V
OUT
≈
3V
IN
. The combination of high
duty cycle and the current limit feature enables continuous
mode operation in many applications, increasing available
output power.
U
OSCILLATOR
1.25V
REFERENCE
V
IN
GND
SENSE
COMPARATOR
A2
A1
DRIVER
I
LIM
SW1
SW2
AO
GAIN BLOCK/
ERROR AMP
SET
1107 BD02
R1
R2
220k
LT1107-5: R1 = 73.5k
LT1107-12: R1 = 25.5k
OSCILLATOR
1.25V
REFERENCE
V
IN
GND
FB
COMPARATOR
A2
A1
DRIVER
I
LIM
SW1
SW2
1107 BD01
AO
GAIN BLOCK/
ERROR AMP
SET
LT1107
LT1107-5/LT1107-12
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 LT1107-5 and LT1107-12 are functionally identical to
the LT1107. 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.
相關PDF資料 |
PDF描述 |
|---|---|
| LT1117IST-2.85 | THREE-TERMINAL POSITIVE FIXED VOLTAGE REGULATORS |
| LT1117IST-3.3 | THREE-TERMINAL POSITIVE FIXED VOLTAGE REGULATORS |
| LT1117IST-5 | THREE-TERMINAL POSITIVE FIXED VOLTAGE REGULATORS |
| LT1118CST8-2.5 | Analog IC |
| LT1118CST8-2.85 | Analog IC |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LT1105I | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Offline Switching Regulator |
| LT1105IN | 功能描述:IC OFFLINE SWIT CM HV 14DIP RoHS:否 類別:集成電路 (IC) >> PMIC - AC-DC 轉換器，離線開關 系列:- 標準包裝:3,000 系列:- 輸出隔離:隔離 頻率范圍:61kHz ~ 71kHz 輸入電壓:9.4 V ~ 28 V 輸出電壓:12V 功率（瓦特）:- 工作溫度:-40°C ~ 125°C 封裝/外殼:SC-74，SOT-457 供應商設備封裝:6-TSOP 包裝:帶卷 (TR) |
| LT1105IN#PBF | 制造商:Linear Technology 功能描述:Conv DC-DC Single 30V 14-Pin PDIP N |
| LT1105IN8 | 功能描述:IC OFFLINE SWIT CM HV 8DIP RoHS:否 類別:集成電路 (IC) >> PMIC - AC-DC 轉換器，離線開關 系列:- 標準包裝:3,000 系列:- 輸出隔離:隔離 頻率范圍:61kHz ~ 71kHz 輸入電壓:9.4 V ~ 28 V 輸出電壓:12V 功率（瓦特）:- 工作溫度:-40°C ~ 125°C 封裝/外殼:SC-74，SOT-457 供應商設備封裝:6-TSOP 包裝:帶卷 (TR) |
| LT1105IN8#PBF | 制造商:Linear Technology 功能描述:Conv DC-DC Single 30V 8-Pin PDIP N |
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