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| 型号： | LTC3834IUFD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 18/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 20-QFN |
| 标准包装： | 73 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 580kHz |
| 占空比： | 99.4% |
| 电源电压： | 4 V ~ 36 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： | 20-WFQFN 裸露焊盘 |
| 包装： | 管件 |
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LTC3834
APPLICATIONS INFORMATION
Topside MOSFET Driver Supply (C B , D B )
External bootstrap capacitors, C B , connected to the BOOST
pins supply the gate drive voltages 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 de-
sired MOSFET. This enhances the MOSFET and turns on
the topside switch. 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 topside MOSFET. The reverse breakdown of the
external Schottky diode must be greater than V IN(MAX) .
When adjusting the gate drive level, the ?nal arbiter is the
Fault Conditions: Current Limit and Current Foldback
The LTC3834 includes current foldback to help limit load
current when the output is shorted to ground. If the out-
put falls below 70% of its nominal output level, then the
maximum sense voltage is progressively lowered from
100mV to 30mV. Under short-circuit conditions with very
low duty cycles, the LTC3834 will begin cycle skipping in
order to limit the short-circuit current. In this situation
the bottom MOSFET will be dissipating most of the power
but less than in normal operation. The short-circuit ripple
current is determined by the minimum on-time, t ON(MIN) ,
of the LTC3834 (≈200ns), the input voltage and inductor
value:
Δ I L(SC) = t ON(MIN) (V IN /L)
The resulting short-circuit current is:
– Δ I L ( SC )
total input current for the regulator. If a change is made
and the input current decreases, then the ef?ciency has
improved. If there is no change in input current, then
I SC =
30 mV
R SENSE
1
2
there is no change in ef?ciency.
Fault Conditions: Overvoltage Protection (Crowbar)
C IN
+
V IN
1μF
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
LTC3834
V IN
TG1
BAT85
0.22μF
VN2222LL
BAT85
BAT85
currents to ?ow, that blow the fuse to protect against a
shorted top MOSFET if the short occurs while the control-
ler is operating.
EXTV CC
SW
BG1
PGND
N-CH
N-CH
L1
R SENSE
+
V OUT
C OUT
A comparator monitors the output for overvoltage con-
ditions. The comparator (OV) detects overvoltage 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
Figure 6. Capacitive Charge Pump for EXTV CC
3834 F06
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 accom-
modate the leakage.
3834fb
18
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| LTC3835EDHC-1 | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Sync Step Down 4V to 36V Input 16-Pin DFN EP |
| LTC3835EDHC-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-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: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 |
| LTC3835EDHC-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-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) |
| LTC3835EFE#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: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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