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参数资料
| 型号： | LTC3772EDDB#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 9/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 8-DFN |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 650kHz |
| 占空比： | 100% |
| 电源电压： | 2.75 V ~ 9.8 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 8-WFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
LTC3772
OPERATIO
(Refer to the Functional Diagram)
Overvoltage Protection
If V FB exceeds its regulation point of 0.8V by more than
10% for any reason, such as an output short-circuit to a
higher voltage, the overvoltage comparator will hold the
external P-channel MOSFET off. This comparator has a
typical hysteresis of 40mV.
However, once the controller’s duty cycle exceeds 20%,
slope compensation begins and effectively reduces the
peak sense voltage by a scale factor given by the curve in
Figure 1.
The peak inductor current is determined by the peak sense
voltage and the on-resistance of the external P-channel
MOSFET:
Peak Current Sense Voltage Selection and Slope
Compensation (I PRG Pins)
When a controller is operating below 20% duty cycle, the
peak current sense voltage (between the SENSE + and SW
I PEAK =
? V SENSE(MAX)
R DS ( ON )
pins) allowed across the external P-channel MOSFET is
determined by:
Soft-Start
The start-up of V OUT is controlled by the LTC3772 internal
? V SENSE ( MAX ) =
A( V ITH – 0.7 V )
10
– 0 . 015
soft-start. During soft-start, the error amplifier EAMP
compares the feedback signal V FB to the internal soft-start
ramp (instead of the 0.8V reference), which rises linearly
where A is a constant determined by the state of the I PRG
pins. Floating the I PRG pin selects A = 1.58; tying I PRG to
V IN selects A = 2.2; tying I PRG to SGND selects A = 0.97.
The maximum value of V ITH is typically about 1.98V, so the
maximum sense voltage allowed across the external
P-channel MOSFET is 175mV, 100mV or 250mV for the
three respective states of the I PRG pin.
100
90
80
70
60
50
40
30
20
10
from 0V to 0.8V in about 0.6ms. This allows the output
voltage to rise smoothly from 0V to its final value, while
maintaining control of the inductor current. After the
soft-start is timed out, it is disabled until the part is put in
shutdown again or the input supply is cycled.
0
0
10 20 30 40 50 60 70 80 90 100
DUTY CYCLE (%)
3772 F01
Figure 1. Reduction in Sense Voltage Due to
Slope Compensation vs Duty Cycle
3772f
9
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3772ETS8 | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Step Down 2.75V to 9.8V Input 8-Pin TSOT-23 |
| LTC3772ETS8#PBF | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Step Down 2.75V to 9.8V Input 8-Pin TSOT-23 |
| LTC3772ETS8#TR | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Step Down 2.75V to 9.8V Input 8-Pin TSOT-23 T/R |
| LTC3772ETS8#TRM | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Step Down 2.75V to 9.8V Input 8-Pin TSOT-23 T/R |
| LTC3772ETS8#TRMPBF | 功能描述:IC REG CTRLR BUCK PWM TSOT23-8 RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
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