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参数资料
| 型号： | LTC3810HUH-5#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 21/38页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 32-QFN |
| 标准包装： | 73 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 占空比： | 99% |
| 电源电压： | 4.35 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 ~ 150°C |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 包装： | 管件 |
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LTC3810-5
APPLICATIONS INFORMATION
R NDRV ≤
I C = ?
? 5.5V ?
? 75 μ s ? ? INTVCC
V IN istypicallymuchhigherthan14Vaseparatesupply
for the IC power (INTV CC ) and driver power (DRV CC ) must
be used. The LTC3810-5 has integrated bias supply con-
trol circuitry that allows the IC/driver supply to be easily
generated from V IN and/or V OUT with minimal external
components. There are four ways to do this as shown in
the simplified schematics of Figure 3 and explained in the
following sections.
Using the Linear Regulator for INTV CC /DRV CC Supply
In Mode 1, a small external SOT23 MOSFET, controlled
by the NDRV pin, is used to generate a 5.5V start-up
supply from V IN . The small SOT23 package can be used
because the NMOS is on continuously only during the brief
start-up period. As soon as the output voltage reaches
4.7V, the LTC3810-5 turns off the external NMOS and the
LTC3810-5 regulates the 5.5V supply from the EXTV CC
pin (connected to V OUT or a V OUT derived boost network)
through an internal low dropout regulator. For this mode to
work properly, EXTV CC must be in the range 4.7V < EXTV CC
< 15V. If V OUT < 4.7V, a charge pump or extra winding can
be used to raise EXTV CC to the proper voltage, or alter-
natively, Mode 2 should be used as explained later in this
section. If V OUT is shorted or otherwise goes below the
minimum 4.5V threshold, the MOSFET connected to V IN
is turned back on to maintain the 5.5V supply. However if
the output cannot be brought up within a timeout period,
the drivers are turned off to prevent the SOT23 MOSFET
from overheating. Soft-start cycles are then attempted at
low duty cycle intervals to try to bring the output back up
(see Figure 10). This fault timeout operation is enabled
by choosing the choosing R NDRV such that the resistor
current I NDRV is greater than 270μA by using the follow-
ing formulas:
P MOSFET(MAX) / I CC ? V TH
270 μ A
where
I CC = (f) ( Q G(TOP) + Q G(BOTTOM) ) + 3mA
and V TH is the threshold voltage of the MOSFET.
The value of R NDRV also affects the V IN(MIN) as follows:
V IN(MIN) = V INTVCC(MIN) + (40μA) R NDRV +V T (1)
where V INTVCC(MIN) is normally 4.5V for driving logic-level
MOSFETs. If minimum V IN is not low enough, consider
reducing R NDRV and/or using a Darlington NPN instead
of an NMOS to reduce V T to ~1.4V.
When using R NDRV equal to the computed value, the
LTC3810-5 will enable the low duty cycle soft-start re-
tries only when the desired maximum power dissipation,
P MOSFET(MAX) , in the MOSFET is exceeded and leave the
drivers on continuously otherwise. The shutoff/restart
times are a function of the TRACK/SS capacitor value.
The external NMOS for the linear regulator should be a
standard 3V threshold type (i.e., not a logic-level threshold).
The rate of charge of INTV CC from 0V to 5.5V is controlled
by the LTC3810-5 to be approximately 75μs regardless
of the size of the capacitor connected to the INTV CC pin.
The charging current for this capacitor is approximately:
C
DRIVER POWER
FAULTTIMEOUT
ENABLED
SS/TRACK
FROM V IN
START-UP
DRIVER POWER
F ROM V OUT
DRIVER OFF THRESHOLD
DRIVER POWER
FROM V IN
EXTV CC UV THRESHOLD
I SS/TRACK = 1.4 μ A (SOURCE)
I SS/TRACK = 0.1 μ A (SINK)
V OUT
SHORT-CIRCUIT EVENT
START-UP INTO SHORT-CIRCUIT
TG/BG
38105 F10
Figure 10. Fault Timeout Operation
38105fd
21
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| LTC3810IG | 制造商:Linear Technology 功能描述: |
| LTC3810IG#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP 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) |
| LTC3810IG#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP 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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| LTC3810IUH-5#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-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: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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