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参数资料
| 型号： | LTC3810HUH-5#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 22/38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
5.5 ? 10 5 ? C SS ?
C OUT
I G ? ? larger of or ?
The safe operating area (SOA) for the external NMOS
should be chosen so that capacitor charging does not
damage the NMOS. Excessive values of capacitor are
unnecessary and should be avoided. Typically values in
the 1μF to 10μF work well.
One more design requirement for this mode is the minimum
soft-start capacitor value. The fault timeout is enabled
when SS/TRACK voltage is greater than 4V. This gives the
power supply time to bring the output up before it starts
the timeout sequence. To prevent timeout sequence from
starting prematurely during start-up, a minimum C SS value
is necessary to ensure that V SS/TRACK < 4V until V EXTVCC
> 4.7V. To ensure this, choose:
C SS > C OUT ? (2.3 ? 10 –6 )/I OUT(MAX)
Mode 2 should be used if V OUT is outside of the 4.7V <
EXTV CC < 15V operating range and the extra complexity
of a charge pump or extra inductor winding is not wanted
to boost this voltage above 4.7V. In this mode, EXTV CC is
grounded and the NMOS is chosen to handle the worst-
case power dissipation:
? ?
P MOSFET = ( V IN(MAX) ) ? ( f ) ( Q G(TOP) + Q G(BOTTOM) ) + 3mA ?
To operate properly, the fault timeout operation must be
disabled by choosing
R NDRV > (V IN(MAX) – 5.5V – V TH )/270μA
If the required R NDRV value results in an unacceptable value
for V IN(MIN) (see Equation 1), fault timeout operation can
also be disabled by connecting a 500k to 1Meg resistor
from SS/TRACK pin to INTV CC .
Using Trickle Charge Mode
Trickle charge mode is selected by shorting NDRV and
INTV CC and connecting EXTV CC to V OUT . Trickle charge
mode has the advantage of not requiring an external
MOSFET but takes longer to start up due to slow charge
up of C INTVCC and C DRVCC through R PULLUP (t DELAY = 0.77
? R PULLUP ? C DRVCC ) and usually requires larger INTV CC /
DRV CC capacitor values to hold up the supply voltage dur-
ing start-up. Once the INTV CC /DRV CC voltage reaches the
trickle charge UV threshold of 9V, the drivers will turn on
and start discharging C INTVCC /C DRVCC at a rate determined
by the driver current I G . In order to ensure proper start-
up, C INTVCC /C DRVCC must be chosen large enough so that
the EXTV CC voltage reaches the switchover threshold of
4.7V before C INTVCC /C DRVCC discharges below the falling
UV threshold of 4V. This is ensured if:
C INTVCC + C DRVCC >
?
? I MAX V OUT(REG) ?
Where I G is the gate drive current = (f)(Q G(TOP) +
Q G(BOTTOM) ) and I MAX is the maximum inductor current
selected by V RNG .
For R PULLUP , the value should fall in the following range
to ensure proper start-up:
Min R PULLUP > (V IN(MAX) – 14V)/I CCSR
Max R PULLUP < (V IN(MIN) – 9V)/I Q,SHUTDOWN
Using an External Supply Connected to the INTV CC /
DRV CC Pins
If an external supply is available between 4.5V and 14V,
the supply can be connected directly to the INTV CC /DRV CC
pins. In this mode, INTV CC , EXTV CC and NDRV must be
shorted together.
INTV CC /DRV CC Supply and the EXTV CC Connection
The LTC3810-5 contains an internal low dropout regulator
to produce the 5.5V INTV CC /DRV CC supply from the EXTV CC
pin voltage. This regulator turns on when the EXTV CC pin
is above 4.7V and remains on until EXTV CC drops below
4.45V. This allows the IC/MOSFET power to be derived
from the output or an output derived boost network during
normal operation and from the external NMOS from V IN
during start-up or short-circuit. Using the EXTV CC pin in
this way results in significant efficiency gains compared
to what would be possible when deriving this power
continuously from the typically much higher V IN voltage.
The EXTV CC connection also allows the power supply to
be configured in trickle charge mode in which it starts up
with a high valued “bleed” resistor connected from V IN
to INTV CC to charge up the INTV CC capacitor. As soon as
the output rises above 4.7V the internal EXTV CC regulator
38105fd
22
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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) |
| LTC3810IUH-5#PBF | 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) |
| 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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