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参数资料
| 型号： | LT3434EFE |
| 厂商： | Linear Technology |
| 文件页数： | 22/24页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 3A 16TSSOP |
| 标准包装： | 95 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.25 V ~ 54 V |
| 输入电压： | 3.3 V ~ 60 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 200kHz |
| 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： | 管件 |
| 供应商设备封装： | 16-TSSOP-EP |
LT3434
APPLICATIO S I FOR ATIO
catch diode and connecting the V C compensation to a
ground track carrying significant switch current. In addi-
tion the theoretical analysis considers only first order non-
ideal component behavior. For these reasons, it is important
that a final stability check is made with production layout
and components.
R C
11
LT3434
CURRENT MODE
POWER STAGE
g m = 6
g m = 650 μ
V C ERROR
AMP
–
1.5M +
SW
SW
FB
5
2
R1
12
R2
C FB
OUTPUT
ESR
The LT3434 uses current mode control. This alleviates
many of the phase shift problems associated with the
C C
C F
1.25V
C OUT
inductor. The basic regulator loop is shown in Figure 12.
The LT3434 can be considered as two g m blocks, the error
amplifier and the power stage.
Figure 13 shows the overall loop response with a 470pF V C
capacitor and a typical 100 μ F tantalum output capacitor.
The response is set by the following terms:
Error amplifier: DC gain is set by g m and R O :
EA Gain = 650 μ ? 1.5M = 975
The pole set by C F and R L :
EA Pole = 1/(2 π ? 1.5M ? 470pF) = 226Hz
Unity gain frequency is set by C F and g m :
EA Unity Gain Frequency = 650 μ F/(2 π ? 470pF)
= 220kHz
Powerstage: DC gain is set by g m and R L (assume 10 ? ):
PS DC Gain = 6 ? 10 = 60
3434 F13
Figure 13. Model for Loop Response
the value of R C is increased, transient response will
generally improve but two effects limit its value. First, the
combination of output capacitor ESR and a large R C may
stop loop gain rolling off altogether. Second, if the loop
gain is not rolled off sufficiently at the switching frequency
output ripple will perturb the V C pin enough to cause
unstable duty cycle switching similar to subharmonic
oscillation. This may not be apparent at the output. Small-
signal analysis will not show this since a continuous time
system is assumed.
When checking loop stability the circuit should be oper-
ated over the application’s full voltage, current and tem-
perature range. Any transient loads should be applied and
the output voltage monitored for a well-damped behavior.
Pole set by C OUT and R L :
PS Pole = 1/(2 π ? 100 μ F ? 10) = 159Hz
Unity gain set by C OUT and g m :
PS Unity Gain Freq = 6/(2 π ? 100 μ F) = 94kHz.
Tantalum output capacitor zero is set by C OUT and C OUT
ESR
Output Capacitor Zero = 1/(2 π ? 100 μ F ? 0.1) = 15.9kHz
100
80
40
0
–40
V OUT = 3.3V
C OUT = 100 μ F, 0.1 ?
C F = 470pF
R C = 10k
C C = 4700pF
I LOAD = 1A
180
160
120
80
40
The zero produced by the ESR of the tantalum output
capacitor is very useful in maintaining stability. If the ESR
of the output capacitor is low or better transient response
–80
10
100
1k 10k
FREQUENCY (Hz)
100k
0
1M
3434 F14
is required, a zero can be added to the loop using a resistor
(R C ) in series with the compensation capacitor (C C ). As
Figure 14. Overall Loop Response
3434fb
22
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| LT3434EFE#PBF | 功能描述:IC REG BUCK ADJ 3A 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 |
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| LT3434EFE#TRPBF | 功能描述:IC REG BUCK ADJ 3A 16TSSOP RoHS:是 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 |
| LT3434EFEPBF | 制造商:Linear Technology 功能描述:LT3434 adj 3A Buck SD dc-dc converter |
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