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参数资料
| 型号： | LT1303CS8-5#TR |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 0.75 A SWITCHING REGULATOR, 155 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封装： | SOIC-8 |
| 文件页数： | 9/12页 |
| 文件大小： | 248K |
| 代理商： | LT1303CS8-5#TR |
6
LT1303/LT1303-5
W
I
DAGRA
BLOCK
S
If switch current reaches 1A, causing C2 to trip, switch on-
time is reduced and off-time increases slightly. This allows
continuous operation during bursts. C2 monitors the
voltage across 3
resistor R1 which is directly related to
the switch current. Q2’s collector current is set by the
emitter-area ratio to 0.6% of Q1’s collector current. When
R1’s voltage drop exceeds 18mV, corresponding to 1A
switch current, C2’s output goes high, truncating the on-
time portion of the oscillator cycle and increasing off-time
OPERATION
U
Operation of the LT1303 is best understood by referring to
the Block Diagram in Figure 2. When C1’s negative input,
related to the output voltage by the appropriate resistor-
divider ratio, is higher than the 1.24V reference voltage,
C1’s output is low. C2, A3 and the oscillator are turned off,
drawing no current. Only the reference and C1 consume
current, typically 140
A. When C1’s negative input drops
below 1.24V and overcomes C1’s 6mV hysteresis, C1’s
output goes high, enabling the oscillator, current compara-
tor C2 and driver A3. Quiescent current increases to 2mA
as the device goes into active switching mode. Q1 then
turns on in controlled saturation for nominally 6
s or until
current comparator C2 trips, whichever comes first. The
switch then turns off for approximately 1.5
s,thenturnson
again. The LT1303’s switching causes current to alter-
nately build up in L1 and dump into output capacitor C4 via
D1, increasing the output voltage. When the output is high
enough to cause C1’s output to go high, switching action
ceases. Capacitor C4 is left to supply current to the load
until VOUT decreases enough to force C1’s output high, and
the entire cycle repeats. Figure 4 details relevant wave-
forms. C1’s cycling causes low-to-mid-frequency ripple
voltage on the output. Ripple can be reduced by making the
output capacitor large. The 100
F unit specified results in
ripple of 50mV to 100mV on the 5V output. A 220
F
capacitor will decrease ripple by approximately 50%.
–
+
–
+
–
+
6
7
8
3
2
5
1
4
VIN
R1
3
Q2
1
×
Q1
160
×
SHUTDOWN
LBO
LBI
GND
PGND
R1
474k
R2
156k
C3
C2
C1
FB
SW
OFF
OSCILLATOR
A3
DRIVER
CURRENT
COMPARATOR
HYSTERETIC
COMPARATOR
REFERENCE
1.24V
18mV
LT1303 BD02
Figure 3. LT1303-5 Block Diagram
20
s/DIV
VOUT
100mV/DIV
AC COUPLED
LT1303 F04
Figure 4. Burst Mode Operation in Action
IL
1A/DIV
VSW
5V/DIV
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1303CS8PBF | 制造商:Linear Technology 功能描述:DC-DC Adj. Micropower Low-Battery SOIC8 |
| LT1303IN8-5 | 功能描述:IC REG BOOST 5V 0.2A 8DIP 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 |
| LT1303IN8-5#PBF | 功能描述:IC REG BOOST 5V 0.2A 8DIP 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:20 系列:SIMPLE SWITCHER® 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:12V 输入电压:4 V ~ 60 V PWM 型:电压模式 频率 - 开关:52kHz 电流 - 输出:1A 同步整流器:无 工作温度:-40°C ~ 125°C 安装类型:通孔 封装/外壳:16-DIP（0.300"，7.62mm） 包装:管件 供应商设备封装:16-DIP 其它名称:*LM2575HVN-12LM2575HVN-12 |
| LT1303IS8 | 功能描述:IC REG BOOST ADJ 0.2A 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 |
| LT1303IS8#PBF | 功能描述:IC REG BOOST ADJ 0.2A 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 |
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