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参数资料
| 型号： | LTC1174IN8#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 1 A SWITCHING REGULATOR, 200 kHz SWITCHING FREQ-MAX, PDIP8 |
| 封装： | 0.300 INCH, LEAD FREE, PLASTIC, DIP-8 |
| 文件页数： | 18/20页 |
| 文件大小： | 251K |
| 代理商： | LTC1174IN8#TRPBF |
7
LTC1174
LTC1174-3.3/LTC1174-5
1174fe
(Refer to Functional Diagram)
The LTC1174 uses a constant off-time architecture to
switch its internal P-channel power MOSFET. The off-time
is set by an internal timing capacitor and the operating
frequency is a function of VIN.
The output voltage is set by an internal resistive divider
(LTC1174-3.3 and LTC1174-5) or an external divider re-
turned to VFB Pin 1 (LTC1174). A voltage comparator A1
compares the divided output voltage to a reference voltage
of 1.25V.
To optimize efficiency, the LTC1174 automatically switches
between continuous and Burst Mode
operation. The volt-
age comparator is the primary control element when the
device is in Burst Mode operation, while the current com-
parator controls the output voltage in continuous mode.
During the switch“ON” time, switch current flows through
the 0.1
sense resistor. When this current reaches the
threshold of the current comparator A2, its output signal will
change state, setting the flip-flop and turning the switch off.
The timing capacitor, CT, begins to discharge until its
voltage goes below VTH1. Comparator A4 will then trip,
which resets the flip-flop and causes the switch to turn on
again. Also, the timing capacitor is recharged. The inductor
current will again ramp up until the current comparator A2
trips. The cycle then repeats.
When the load is relatively light, the LTC1174 automatically
goes into Burst Mode operation. The current mode loop is
interrupted when the output voltage reaches the desired
regulated value. The hysteretic voltage comparator A1 trips
when VOUT is above the desired output voltage, shutting off
the switch and causing the timing capacitor to discharge.
This capacitor discharges past VTH1 until its voltage drops
below VTH2. Comparator A5 then trips and a sleep signal is
generated.
In sleep mode, the LTC1174 is in standby and the load
current is supplied by the output capacitor. All unused
circuitry is shut off, reducing quiescent current from
0.45mA to 0.13mA. When the output capacitor discharges
by the amount of the hysteresis of the comparator A1, the
P-channel switch turns on again and the process repeats
itself.
Operating Frequency and Inductor
Since the LTC1174 utilizes a constant off-time architecture,
its operating frequency is dependent on the value of VIN. The
frequency of operation can be expressed as:
f
t
VV
Hz
OFF
IN
OUT
IN
D
=
+
()
1
where tOFF =4sandVDisthevoltagedropacrossthediode.
Note that the operating frequency is a function of the input
and ouput voltage.
Although the size of the inductor does not affect the fre-
quency, it does affect the ripple current. The peak-to-peak
ripple current is given by:
I
VV
L
A
RIPPLE
OUT
D
PP
=
+
()
410 6
By choosing a smaller inductor, a low ESR output filter
capacitor has to be used (see CIN and COUT). Moreover, core
loss will also increase (see Inductor Core Selection section)
due to higher ripple current.
OPERATIO
U
Burst Mode is a registered trademark of Linear Technology Corporation.
相关PDF资料 |
PDF描述 |
|---|---|
| LTC1174CN8#TRPBF | 1 A SWITCHING REGULATOR, 200 kHz SWITCHING FREQ-MAX, PDIP8 |
| LTC1174CN8-5#TRPBF | 1 A SWITCHING REGULATOR, 200 kHz SWITCHING FREQ-MAX, PDIP8 |
| LTC1174CN8-5#TR | 1 A SWITCHING REGULATOR, 200 kHz SWITCHING FREQ-MAX, PDIP8 |
| LTC1174HVCS8#TR-5 | SWITCHING REGULATOR, 200 kHz SWITCHING FREQ-MAX, PDSO8 |
| LTC1174CS8#TR-5 | SWITCHING REGULATOR, 200 kHz SWITCHING FREQ-MAX, PDSO8 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1174IS8 | 功能描述:IC REG BUCK INV ADJ 1A 8SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LTC1174IS8#PBF | 功能描述:IC REG BUCK INV ADJ 1A 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LTC1174IS8#TR | 功能描述:IC REG BUCK INV ADJ 1A 8SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LTC1174IS8#TRPBF | 功能描述:IC REG BUCK INV ADJ 1A 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LTC1177-12 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Isolated MOSFET Drivers |
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