LT1939
1
1939f
TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
Monolithic 2A Step-Down
Regulator Plus Linear
Regulator/Controller
The LT
?/DIV>
1939 is a current mode PWM step-down DC/DC
converter with an internal 2.3A switch. The wide input
range of 3V to 25V makes the LT1939 suitable for regu-
lating power from a wide variety of sources, including
automotive batteries, industrial supplies and unregulated
wall adapters.
Resistor-programmable 250kHz to 2.2MHz frequency
range and synchronization capability enable optimization
between ef ciency and external component size. Cycle-
by-cycle current limit, frequency foldback and thermal
shutdown provide protection against a shorted output.
The soft-start feature controls the ramp rate of the output
voltage, eliminating input current surge during start-up,
and also provides output tracking.
The LT1939 contains an internal NPN transistor with feed-
back control which can be con gured as a linear regulator
or as a linear regulator controller.
The LT1939s low current shutdown mode (<12糀) enables
easy power management in battery-powered systems.
n
Wide Input Range: 3V to 25V
n
Short-Circuit Protected Over Full Input Range
n
2A Output Current Capability
n
Adjustable/Synchronizable Fixed Frequency
Operation from 250kHz to 2.2MHz
n
Soft-Start/Tracking Capability
n
Output Adjustable Down to 0.8V
n
Adjustable Linear Regulator/Driver with 13mA
Output Capability
n
Power Good Comparator with Complementary
Outputs
n
Low Shutdown Current: 12糀
n
Thermally Enhanced 3mm ?3mm DFN Package
n
Automotive Battery Regulation
n
Industrial Control
n
Wall Transformer Regulation
n
Distributed Power Regulation
Dual Step-Down Converters
Output Voltage Ripple
Switching Converter Ef ciency
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
6.8糎
0.47糉
22糉
22糉
42.2k
8.06k
2.2糉
0.47糉
V
IN
6V TO 25V
40.2k
53.6k
330pF
1939 TA01a
V
OUT1
5V
1A
V
OUT2
3.3V
1A
BAT54
B240A
BST
V
IN
SW
FB
SHDN
SS
LT1939
R
T/
SYNC
V
C
LDRV
LFB
PG
PG
8.06k
24.9k
1k
LOAD CURRENT (A)
0
90
85
80
75
70
65
60
55
50
1.6
1939 TA01b
0.4 0.8 1.2
2.0
1.4
0.2 0.6 1.0
1.8
V
IN
= 12V
I
OUT2
= 0A
FREQUENCY = 800kHz
500ns/DIV
1939 TA01c
V
OUT1
= 5V AT 1A
AC COUPLED
2mV/DIV
V
OUT2
= 3.3V AT 1A
AC COUPLED
2mV/DIV
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LT1939IDD-PBF
制造商:LINER 制造商全称:Linear Technology 功能描述:Monolithic 2A Step-Down Regulator Plus Linear Regulator/Controller
LT1939IDD-TRPBF
制造商:LINER 制造商全称:Linear Technology 功能描述:Monolithic 2A Step-Down Regulator Plus Linear Regulator/Controller
LT1940
制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Synchronous,400mA/800mA, 2.25MHz Step-Down DC/DC Regulator
LT1940EFE
功能描述:IC REG BUCK ADJ 1.4A DL 16TSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT
LT1940EFE#PBF
功能描述:IC REG BUCK ADJ 1.4A DL 16TSSOP 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:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2
LT1940EFE#TR
功能描述:IC REG BUCK ADJ 1.4A DL 16TSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT
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LT1940EFEPBF
制造商:Linear Technology 功能描述:LT1940 adj 1.4A SD dc-dc converter