- 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： | 12/20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
I D = ? IN OUT ? I OUT
Under normal load conditions, the average current con-
ducted by the diode is:
? V ? V ?
? V IN + V D ?
The allowable forward voltage drop in the diode is calcu-
lated from the maximum short-circuit current as:
The output filtering capacitor C smooths out current flow
from the inductor to the load, help maintain a steady out-
put voltage during transient load changes and reduce output
voltage ripple. The capacitors must be selected with suf-
ficiently low ESR to minimize voltage ripple and load step
transients and sufficiently bulk capacitance to ensure the
control loop stability.
The output ripple, ? V OUT , is determined by:
? V OUT L ? ESR +
≤ ? I
8 fC OUT ?
V F ?
P D
I PEAK
?
?
1 ?
?
where P D is the allowable power dissipation and will be
determined by efficiency and/or thermal requirements.
A fast switching diode must also be used to optimize effi-
ciency. Schottky diodes are a good choice for low forward
drop and fast switching times. Remember to keep lead
length short and observe proper grounding to avoid ring-
ing and increased dissipation.
An additional consideration in applications where low no-
load quiescent current is critical is the reverse leakage
current of the diode at the regulated output voltage. A leak-
age greater than several microamperes can represent a
significant percentage of the total input current.
C IN and C OUT Selection
The input capacitance, C IN , is needed to filter the trapezoi-
dal current at the source of the top MOSFET. To prevent large
ripple voltage, a low ESR input capacitor sized for the
maximum RMS current should be used. RMS current is
given by:
The output ripple is highest at maximum input voltage since
? I L increases with input voltage. Multiple capacitors placed
in parallel may be needed to meet the ESR and RMS cur-
rent handling requirements. Dry tantalum, special polymer,
aluminum electrolytic and ceramic capacitors are all avail-
able in surface mount packages. Special polymer capaci-
tors offer very low ESR but have lower capacitance density
than other types. Tantalum capacitors have the highest
capacitance density but it is important to only use types
that have been surge tested for use in switching power sup-
plies. Aluminum electrolytic capacitors have significantly
higher ESR but can be used in cost-sensitive applications
provided that consideration is given to ripple current rat-
ings and long term reliability. Ceramic capacitors have
excellent low ESR characteristics but can have a high
voltage coefficient and audible piezoelectric effects. The
high Q of ceramic capacitors with trace inductance can also
lead to significant ringing.
Using Ceramic Input and Output Capacitors
I RMS = I OUT ( MAX )
V OUT
V IN
V IN
V OUT
–1
Higher values, lower cost ceramic capacitors are now
becoming available in smaller case sizes. Their high ripple
current, high voltage rating and low ESR make them ideal
This formula has a maximum at V IN = 2V OUT , where I RMS
= I OUT /2. This simple worst-case condition is commonly
used for design because even significant deviations do not
offer much relief. Note that ripple current ratings from
capacitor manufacturers are often based on only 2000 hours
of life which makes it advisable to further derate the capaci-
tor, or choose a capacitor rated at a higher temperature than
required. Several capacitors may also be paralleled to meet
size or height requirements in the design.
for switching regulator applications. However, care must
be taken when these capacitors are used at the input and
output. When a ceramic capacitor is used at the input and
the power is supplied by a wall adapter through long wires,
a load step at the output can induce ringing at the input, V IN .
At best, this ringing can couple to the output and be mis-
taken as loop instability. At worst, a sudden inrush of cur-
rent through the long wires can potentially cause a voltage
spike at V IN large enough to damage the part.
3772bfa
12
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。