- 您现在的位置：买卖IC网 > PDF目录15342 > LTC3772BEDDB#TRMPBF (Linear Technology)IC REG CTRLR BUCK PWM CM 8-DFN PDF资料下载
参数资料
| 型号： | LTC3772BEDDB#TRMPBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 8-DFN |
| 标准包装： | 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) |
LTC3772B
APPLICATIO S I FOR ATIO
The basic LTC3772B application circuit is shown on the front
page of this data sheet. The load requirement drives the
selection of external components: the power MOSFET,
inductor and output diode, as well as the input bypass
However, for operation above 20% duty cycle, slope com-
pensation has to be taken into consideration to select the
appropriate value of R DS(ON) for the required amount of load
current:
capacitor C IN and output bypass capacitor C OUT .
Power MOSFET Selection
R DS ( ON )( MAX ) =
5 ? V SENSE ( MAX ) – SF
?
6 I OUT ( MAX )
An external P-channel power MOSFET must be selected for
use with the LTC3772B. The main selection criteria for the
power MOSFET are the threshold voltage V GS(TH) , the “on”
resistance R DS(ON) , reverse transfer capacitance C RSS and
total gate charge.
Since the LTC3772B is designed for operation down to low
input voltages, a sublogic level threshold MOSFET (R DS(ON)
guaranteed at V GS = 2.5V) is required for applications that
work close to this voltage. When these MOSFETs are used,
where SF is a factor whose value is obtained from the curve
in Figure 1.
These must be further derated to take into account the
significant variation in on-resistance with temperature. The
following equation is a good guide for determining the
required R DS(ON)MAX at 25 ° C (manufacturer’s specifica-
tion), allowing some margin for variations in the LTC3772B
and external component values:
make sure that the input supply to the LTC3772B is less than
the absolute maximum V GS rating.
The P-channel MOSFET’s on-resistance is chosen based on
R DS ( ON )( MAX ) =
5
6
? 0 . 9 ?
? V SENSE ( MAX ) – SF
I OUT ( MAX ) ? ρ T
the required load current. The maximum average output
load current I OUT(MAX) is equal to the peak inductor current
minus half the peak-to-peak ripple current I RIPPLE . The
LTC3772B’s current comparator monitors the drain-to-
source voltage V DS of the P-channel MOSFET, which is
sensed between the V IN and SW pins. The peak inductor
current is limited by the current threshold, set by the volt-
age on the I TH pin of the current comparator. The voltage
on the I TH pin is internally clamped, which limits the maxi-
mum current sense threshold ? V SENSE(MAX) to approxi-
mately 138mV when I PRG is floating (70mV when I PRG is
tied low; 208mV when I PRG is tied high).
The output current that the LTC3772B can provide is given by:
The ρ T is a normalizing term accounting for the tempera-
ture variation in on-resistance, which is typically about
0.4%/ ° C, as shown in Figure 2. Junction to case tempera-
ture T JC is about 10 ° C in most applications. For a maximum
ambient temperature of 70 ° C, using ρ 80 ° C ? 1.3 in the above
equation is a reasonable choice.
The required minimum R DS(ON) of the MOSFET is also
governed by its allowable power dissipation. For applica-
tions that may operate the LTC3772B in dropout–i.e., 100%
2.0
1.5
– RIPPLE
I OUT ( MAX ) =
? V SENSE ( MAX )
R DS ( ON )
I
2
1.0
A reasonable starting point is setting ripple current I RIPPLE
to be 40% of I OUT(MAX) . Rearranging the above equation
yields:
0.5
5 ? V SENSE ( MAX )
R DS ( ON )( MAX ) =
6 I OUT ( MAX )
?
0
– 50
0 50 100 150
JUNCTION TEMPERATURE ( ? C)
3772B F02
for Duty Cycle < 20%.
Figure 2. R DS(ON) vs Temperature
3772bfa
10
相关PDF资料 |
PDF描述 |
|---|---|
| HCC22DRTS | CONN EDGECARD 44POS DIP .100 SLD |
| VE-BWP-EV-F3 | CONVERTER MOD DC/DC 13.8V 150W |
| GMC19DRXI | CONN EDGECARD 38POS DIP .100 SLD |
| LTC1622CMS8#TR | IC REG CTRLR BUCK PWM CM 8-MSOP |
| VE-BWP-EV-F2 | CONVERTER MOD DC/DC 13.8V 150W |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3772BETS8#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) |
| LTC3772BETS8#TRPBF | 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) |
| LTC3772EDDB#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 DFN EP |
| LTC3772EDDB#TRMPBF | 功能描述:IC REG CTRLR BUCK PWM CM 8-DFN 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) |
| LTC3772EDDB#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 8-DFN 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) |
发布紧急采购，3分钟左右您将得到回复。