- 您现在的位置：买卖IC网 > PDF目录4956 > LTC3891EUDC#PBF (Linear Technology)IC REG CTRLR BUCK PWM CM 20-QFN PDF资料下载
参数资料
| 型号： | LTC3891EUDC#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 21/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 20-QFN |
| 标准包装： | 91 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 835kHz |
| 占空比： | 99% |
| 电源电压： | 4 V ~ 60 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 ~ 125°C |
| 封装/外壳： | 20-WFQFN 裸露焊盘 |
| 包装： | 管件 |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页当前第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页
LTC3891
APPLICATIONS INFORMATION
NDS7002
L
R SENSE
Δ I L(SC) = t ON(MIN) ? IN ?
4. EXTV CC ConnectedtoanOutput-DerivedBoostNetwork.
For 3.3V and other low voltage regulators, efficiency
gains can still be realized by connecting EXTV CC to an
output-derived voltage that has been boosted to greater
than 4.7V. This can be done with the capacitive charge
pump shown in Figure 8. Ensure that EXTV CC < V IN .
C IN
BAT85 BAT85
V IN
MTOP
BAT85
TG
LTC3891
EXTV CC SW V OUT
MBOT
BG C OUT
Fault Conditions: Current Limit and Current Foldback
The LTC3891 includes current foldback to help limit load
current when the output is shorted to ground. If the output
voltage falls below 70% of its nominal output level, then
the maximum sense voltage is progressively lowered from
100% to 45% of its maximum selected value. Under short-
circuit conditions with very low duty cycles, the LTC3891
will begin cycle skipping in order to limit the short-circuit
current. In this situation the bottom MOSFET will be dis-
sipating most of the power but less than in normal opera-
tion. The short-circuit ripple current is determined by the
minimum on-time, t ON(MIN) , of the LTC3891 (≈95ns), the
input voltage and inductor value:
? V ?
? L ?
PGND
3891 F08
The resulting average short-circuit current is:
I SC = 45% ? I LIM(MAX) – D I L(SC)
Figure8.CapacitiveChargePumpforEXTV CC
Topside MOSFET Driver Supply (C B , D B )
An external bootstrap capacitor, C B , connected to the
BOOST pin supplies the gate drive voltage for the topside
MOSFET. Capacitor C B in the Functional Diagram is charged
though external diode D B from INTV CC when the SW pin
is low. When the topside MOSFET is to be turned on, the
driver places the C B voltage across the gate-source of
the MOSFET. This enhances the top MOSFET switch and
turns it on. The switch node voltage, SW, rises to V IN and
the BOOST pin follows. With the topside MOSFET on, the
boost voltage is above the input supply: V BOOST = V IN +
V INTVCC . The value of the boost capacitor, C B , needs to be
100 times that of the total input capacitance of the top-
side MOSFET(s). The reverse breakdown of the external
Schottky diode must be greater than V IN(MAX) .
When adjusting the gate drive level, the final arbiter is the
total input current for the regulator. If a change is made
and the input current decreases, then the efficiency has
improved. If there is no change in input current, then there
is no change in efficiency.
1
2
Fault Conditions: Overvoltage Protection (Crowbar)
The overvoltage crowbar is designed to blow a system
input fuse when the output voltage of the regulator rises
much higher than nominal levels. The crowbar causes huge
currents to flow, that blow the fuse to protect against a
shorted top MOSFET if the short occurs while the control-
ler is operating.
A comparator monitors the output for overvoltage condi-
tions. The comparator detects faults greater than 10%
above the nominal output voltage. When this condition
is sensed, the top MOSFET is turned off and the bottom
MOSFET is turned on until the overvoltage condition is
cleared. The bottom MOSFET remains on continuously
for as long as the overvoltage condition persists; if V OUT
returns to a safe level, normal operation automatically
resumes.
A shorted top MOSFET will result in a high current condition
which will open the system fuse. The switching regulator
will regulate properly with a leaky top MOSFET by altering
the duty cycle to accommodate the leakage.
3891fa
21
相关PDF资料 |
PDF描述 |
|---|---|
| HBM36DSEH-S13 | CONN EDGECARD 72POS .156 EXTEND |
| ECM18DKLH | CONN EDGECARD 36POS .156 WW |
| HCM36DRTN-S13 | CONN EDGECARD 72POS .156 EXTEND |
| GCE45DHRN | CONN CARD EXTEND 90POS 1MM SLD |
| HBM36DRTN-S13 | CONN EDGECARD 72POS .156 EXTEND |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3891HFE#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 20TSSOP 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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3891HFE#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 20TSSOP 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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3891HUDC#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 20-QFN 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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3891HUDC#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 20-QFN 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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3891IFE#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 20TSSOP 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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
发布紧急采购，3分钟左右您将得到回复。