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參數(shù)資料
| 型號： | LTC1574 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | High Efficiency Step-Down DC/DC Converters with Internal Schottky Diode(可調(diào)輸出，高效率步降DC/DC變換器（內(nèi)部帶肖特基二極管）) |
| 中文描述： | 高效降壓DC / DC轉(zhuǎn)換器的內(nèi)部肖特基二極管（可調(diào)輸出，高效率步降直流/直流變換器（內(nèi)部帶肖特基二極管）） |
| 文件頁數(shù)： | 4/8頁 |
| 文件大?。?/td> | 161K |
| 代理商： | LTC1574 |
4
LTC1574
LTC1574-3.3/LTC1574-5
V
OUT
or V
FB
(Pin 10):
For the LTC1574, this pin connects
t
o the main voltage comparator input. On the LTC1574-5
and LTC1574-3.3, this pin goes to an internal resistive
divider which sets the output voltage
.
LB
OUT
(Pin 11):
Open drain of an N-Channel Pull-Down.
This pin will sink current when (Pin 12) LB
IN
goes below
1.25V.
LB
IN
(Pin 12):
The (–) Input of the Low-Battery Voltage
Comparator. The (+) input is connected to a reference
voltage of 1.25V.
NC (Pins 1, 8, 9, 16):
No Connection.
GND (Pins 2, 4, 13, 15):
Ground.
SW (Pins 3, 14):
Drain of P-Channel MOSFET Switch and
Cathode of Schottky Diode.
V
IN
(Pin 5):
Input Supply Voltage. It must be decoupled
close to ground (Pin 4).
I
PGM
(Pin 6):
This pin selects the current limit of the
P-channel switch. With I
PGM
= V
IN
, the current trip point is
600mA and with I
PGM
= 0V, the current trip point is
reduced to 340mA.
SHDN (Pin 7):
Pulling this pin to ground keeps the internal
switch off and puts the LTC1574 in micropower shutdown.
Operating Frequency and Inductor
Since the LTC1574 utilizes a constant off-time architecture,
its operating frequency is dependent on the value of V
IN
. The
frequency of operation can be expressed as:
f
t
V
V
V
V
Hz
OFF
IN
OUT
IN
D
=
+
( )
1
where t
OFF
= 4
μ
s and V
D
is the voltage drop across the
internal Schottky diode. Note that the operating frequency
is a function of the input and output voltage.
Although the size of the inductor does not affect the fre-
quency or inductor peak current, it does affect the ripple
current. The peak-to-peak ripple current is given by:
I
V
V
L
RIPPLE
OUT
D
=
+
(
)
4 10
6
A
P-P
When choosing a small inductor, core loss will increase due
to higher ripple current. Therefore, a low ESR output
capacitor has to be used.
Short-Circuit Protection
The LTC1574 is protected from output short circuits by its
internal current limit. Depending on the condition of the
Low-Battery Detector
The low-battery indicator senses the input voltage through
an external resistive divider. This divided voltage connects
to the “–” input of a voltage comparator (Pin 12) which is
compared with a 1.25V reference voltage. With the current
I
PGM
pin, the limit is either set to 340mA or 600mA. In
addition, the off-time of the switch is increased to allow the
inductor current to decay far enough to prevent any current
build-up (see Figure 1).
I
PGM
= V
IN
I
PGM
= 0
GND
L = 100
μ
H
V
IN
= 13.5V
1
20
μ
s/DIV
1574 F01
Figure 1. Inductor Current with Output Shorted
PIU
APPLICATIU
W
U
U
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| LTC1574CS#PBF | 功能描述:IC REG BUCK INV ADJ 16SOIC 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 |
| LTC1574CS#TR | 功能描述:IC REG BUCK INV ADJ 16SOIC 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:- 設(shè)計資源:Design Support Tool 標(biāo)準(zhǔn)包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:100mA 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:SOT-23-5 細型，TSOT-23-5 包裝:剪切帶 (CT) 供應(yīng)商設(shè)備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT |
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