参数资料
| 型号： | LT3431IFE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 23/28页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 3A 16TSSOP |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.2 V ~ 48 V |
| 输入电压： | 5.5 V ~ 60 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 500kHz |
| 电流 - 输出： | 3A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 16-TSSOP-EP |
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LT3431
APPLICATIO S I FOR ATIO
BUCK CONVERTER WITH ADJUSTABLE SOFT-START
Large capacitive loads or high input voltages can cause
high input currents at start-up. Figure 13 shows a circuit
that limits the dv/dt of the output at start-up, controlling
the capacitor charge rate. The buck converter is a typical
configuration with the addition of R3, R4, C SS and Q1.
As the output starts to rise, Q1 turns on, regulating switch
current via the V C pin to maintain a constant dv/dt at the
output. Output rise time is controlled by the current
through C SS defined by R4 and Q1’s V BE . Once the output
is in regulation, Q1 turns off and the circuit operates
normally. R3 is transient protection for the base of Q1.
Dual Polarity Output Converter
The circuit in Figure 14a generates both positive and
negative 5V outputs with all components under 3mm
height. The topology for the 5V output is a standard buck
converter. The –5V output uses a second inductor L2,
diode D3, and output capacitor C6. The capacitor C4
couples energy to L2 and ensures equal voltages across
L2 and L1 during steady state. Instead of using a trans-
former for L1 and L2, uncoupled inductors were used
because they require less height than a single transformer,
can be placed separately in the circuit layout for optimized
space savings and reduce overall cost. This is true even
Rise Time =
( R 4 )( C SS )( V OUT )
V BE
when the uncoupled inductors are sized (twice the value of
inductance of the transformer) in order to keep ripple
current comparable to the transformer solution. If a single
transformer becomes available to provide a better height
( )( ) ( ) 5 = 5 ms
47 ? 10 15 ? 10
Using the values shown in Figure 10,
3 – 9
Rise Time =
0 . 7
The ramp is linear and rise times in the order of 100ms are
possible. Since the circuit is voltage controlled, the ramp
rate is unaffected by load characteristics and maximum
output current is unchanged. Variants of this circuit can be
used for sequencing multiple regulator outputs.
D2
MMSD914TI
/cost solution, refer to the Dual Output SEPIC circuit
description in Design Note 100 for correct transformer
connection.
During switch on-time, in steady state, the voltage across
both L1 and L2 is positive and equal ; with energy (and
current) ramping up in each inductor. The current in L2 is
provided by the coupling capacitor C4. During switch off-
time, current ramps downward in each inductor. The
current in L2 and C4 flows via the catch diode D3, charging
the negative output capacitor C6. If the negative output is
not loaded enough it can go severely unregulated (become
more negative). Figure 14b shows the maximum allow-
0.22 μ F
C1
10V
INPUT
12V
C3
4.7 μ F
25V
CER
BOOST BIAS
LT3431
SHDN FB
V IN SW
C2
L1
15 μ H
D1
30BQ060 100 μ F
OR B250A
+
R1
15.4k
OUTPUT
5V
2A
able –5V output load current (vs load current on the 5V
output) that will maintain the –5V output within 3%
tolerance. Figure 14c shows the –5V output voltage regu-
lation versus its own load current when plotted for three
SYNC GND
V C
R2
4.99k
separate load currents on the 5V output. The efficiency of
R C
3.3k
C C
0.022 μ F
C F
220pF Q1
R3
2k
R4
47k
C SS
15nF
3431 F13
the dual polarity output converter circuit shown in Figure
14a is given in Figure 14d.
L1: CDRH104R-220M
Figure 13. Buck Converter with Adjustable Soft-Start
sn3431 3431fs
23
相关PDF资料 |
PDF描述 |
|---|---|
| LT3433IFE#TRPBF | IC REG BUCK BST ADJ 0.5A 16TSSOP |
| LT3434IFE#TRPBF | IC REG BUCK ADJ 3A 16TSSOP |
| LT3435IFE#TRPBF | IC REG BUCK ADJ 3A 16TSSOP |
| LT3436EFE#TRPBF | IC REG BOOST ADJ 3A 16TSSOP |
| LT3437EDD#PBF | IC REG BUCK ADJ 0.5A 10DFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3433 | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Voltage Step-Up/Step-Down DC/DC Converter |
| LT3433_1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Voltage Step-Up/Step-Down DC/DC Converter |
| LT3433EFE | 功能描述:IC REG BUCK BST ADJ 0.5A 16TSSOP 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 |
| LT3433EFE#PBF | 功能描述:IC REG BUCK BST ADJ 0.5A 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 |
| LT3433EFE#TR | 功能描述:IC REG BUCK BST ADJ 0.5A 16TSSOP 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 |
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