參數(shù)資料
型號(hào): LTC1871HMS
廠商: LINEAR TECHNOLOGY CORP
元件分類(lèi): 穩(wěn)壓器
英文描述: 0.05 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO10
封裝: PLASTIC, MSOP-10
文件頁(yè)數(shù): 35/36頁(yè)
文件大小: 519K
代理商: LTC1871HMS
LTC1871
8
1871fe
BLOCK DIAGRAM
+
+
1.230V
85mV
OV
50k
EA
UV
TO
START-UP
CONTROL
BURST
COMPARATOR
S
R
Q
LOGIC
PWM LATCH
CURRENT
COMPARATOR
0.30V
1.230V
5.2V
+
2.00V
1.230V
SLOPE
1.230V
ILOOP
FB
ITH
+
gm
3
MODE/SYNC
5
FREQ
4
2
INTVCC
8
LDO
V-TO-I
OSC
V-TO-I
SLOPE
COMPENSATION
BIAS AND
START-UP
CONTROL
VIN
BIAS
VREF
IOSC
RLOOP
+
+
C1
SENSE
10
GND
1871 BD
6
GATE
INTVCC
GND
7
VIN
1.248V
9
RUN
C2
1
0.6V
Main Control Loop
The LTC1871 is a constant frequency, current mode con-
troller for DC/DC boost, SEPIC and yback converter ap-
plications. The LTC1871 is distinguished from conventional
current mode controllers because the current control loop
can be closed by sensing the voltage drop across the power
MOSFET switch instead of across a discrete sense resistor,
as shown in Figure 2. This sensing technique improves
efciency, increases power density, and reduces the cost
of the overall solution.
For circuit operation, please refer to the Block Diagram of
the IC and Figure 1. In normal operation, the power MOSFET
is turned on when the oscillator sets the PWM latch and
is turned off when the current comparator C1 resets the
latch. The divided-down output voltage is compared to an
internal 1.230V reference by the error amplier EA, which
outputs an error signal at the ITH pin. The voltage on the
ITH pin sets the current comparator C1 input threshold.
When the load current increases, a fall in the FB voltage
relative to the reference voltage causes the ITH pin to rise,
which causes the current comparator C1 to trip at a higher
peak inductor current value. The average inductor current
will therefore rise until it equals the load current, thereby
maintaining output regulation.
OPERATION
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
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LTC1871HMSPBF 制造商:Linear Technology 功能描述:PWM Controller Current Mode MSOP10
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LTC1871IMS#PBF 功能描述:IC REG CTRLR BST FLYBK CM 10MSOP RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無(wú) 升壓:是 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤(pán) 包裝:帶卷 (TR)