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參數(shù)資料
| 型號： | LT1931ES5 |
| 文件頁數(shù)： | 4/12頁 |
| 文件大?。?/td> | 210K |
| 代理商： | LT1931ES5 |
4
LT1931/LT1931A
BLOCK DIAGRA
Figure 2
OPERATIOU
The LT1931 uses a constant frequency, current mode
control scheme to provide excellent line and load regula-
tion. Operation can be best understood by referring to the
Block Diagram in Figure 2. At the start of each oscillator
cycle, the SR latch is set, turning on the power switch Q3.
A voltage proportional to the switch current is added to a
stabilizing ramp and the resulting sum is fed into the
positive terminal of the PWM comparator A2. When this
voltage exceeds the level at the negative input of A2, the SR
latch is reset, turning off the power switch. The level at the
negative input of A2 is set by the error amplifier (g
m
) and
is simply an amplified version of the difference between
the feedback voltage and the reference voltage of –1.255V.
In this manner, the error amplifier sets the correct peak
current level to keep the output in regulation. If the error
amplifier’s output increases, more current is taken from
the output; if it decreases, less current is taken. One
function not shown in Figure 2 is the current limit. The
switch current is constantly monitored and not allowed to
exceed the nominal value of 1.2A. If the switch current
reaches 1.2A, the SR latch is reset regardless of the state
of comparator A2. This current limit protects the power
switch as well as various external components connected
to the LT1931.
The Block Diagram for the LT1931A is identical except that
the oscillator is 2.2MHz and resistors R3 to R6 are one-half
the LT1931 values.
–
+
–
+
LATCH
R
Q
S
0.01
SW
DRIVER
COMPARATOR
2
SHUTDOWN
SHDN
4
1
–
+
Σ
RAMP
GENERATOR
R
C
C
C
1.2MHz
OSCILLATOR
GND
1931 BD
R6
80k
R4
150k
R3
30k
Q2
x10
Q1
Q3
R5
80k
V
IN
V
IN
5
NFB
C
PL
(OPTIONAL)
R2
(EXTERNAL)
R1
(EXTERNAL)
V
OUT
NFB
3
A2
A1
g
m
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LT1D90A | CHIP LEDs |
| LT1H90A | CHIP LEDs |
| LT1K90A | CHIP LEDs (Taped models only) |
| LT2402-SERIES | Optoelectronic |
| LT2462-SERIES | Optoelectronic |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT1931ES5#PBF | 制造商:Linear Technology 功能描述:Conv DC-DC Single Inv 2.45V to 16V 5-Pin TSOT-23 制造商:Linear Technology 功能描述:IC SEMICONDUCTOR ((NS)) 制造商:Linear Technology 功能描述:IC, DC/DC CONVERTER, 5-TSOT-23; Primary Input Voltage:16V; No. of Outputs:1; Output Voltage:-12V; Output Current:350mA; No. of Pins:5; Operating Temperature Min:-40C; Operating Temperature Max:85C; MSL:MSL 1 - Unlimited ;RoHS Compliant: Yes |
| LT1931ES5#PBF | 制造商:Linear Technology 功能描述:IC |
| LT1931ES5#TR | 功能描述:IC REG INV 1A TSOT23-5 RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC |
| LT1931ES5#TRM | 功能描述:IC REG INV 1A TSOT23-5 RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC |
| LT1931ES5#TRMPBF | 功能描述:IC REG INV 1A TSOT23-5 RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:250 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開關(guān):2MHz 電流 - 輸出:500mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:6-UFDFN 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:6-SON（1.45x1） 產(chǎn)品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
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