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参数资料
| 型号： | LTC3811EUHF#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 17/48页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 38-QFN |
| 标准包装： | 2,500 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 850kHz |
| 占空比： | 90% |
| 电源电压： | 4.5 V ~ 30 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： | 38-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
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LTC3811
OPERATION
(Refer to the Functional Diagram)
If the internal LDO is supplying power to the gate driver
and the input voltage is low enough for the LDO to be in
dropout, then the minimum gate drive supply voltage is:
V DRVCC = V IN(MIN) – V DROPOUT
The LDO dropout voltage is a function of the total gate
drive current and the quiescent current of the IC (typically
10mA). A curve of dropout voltage vs output current for the
LDO is shown in the Typical Performance Characteristics.
The temperature coef?cient of the LDO dropout voltage is
approximately +4000ppm/oC.
The total Q-current (I Q(TOT) ) ?owing in the LDO is the sum
of the controller quiescent current (typically 10mA) and
the total gate charge drive current.
I Q(TOT) = I Q + Q G(TOT) ? f
If an external supply is being used to supply power to the
gate driver through the EXTV CC pin, then the minimum
gate drive supply voltage is:
V DRVCC = V EXTVCC – I Q(TOT) ? R EXTVCC
The resistance of the internal EXTV CC PMOS switch is
typically 5 Ω at 25°C and has a temperature coef?cient of
approximately 3400ppm/°C.
After the calculations have been completed, it is important
to measure the gate drive waveforms (BG-to-PGND and
TG-to-SW) and the gate driver supply voltage (DRV CC -to-
PGND) over all operating conditions (low V IN , mid V IN ,
and high V IN , as well as from light load-to-full load) to
ensure adequate power MOSFET enhancement. Consult
the power MOSFET data sheet to determine the actual
The RUN pins may be externally pulled up or driven di-
rectly by logic. Be careful not to exceed the 7V absolute
maximum rating on this pin.
Soft-Start and Tracking Using the SS/TRACK Pin
The start-up of each controller’s output voltage V OUT
is normally controlled by the voltage on the SS/TRACK
pin for that channel. The SS/TRACK pin represents a
2nd noninverting input to the error ampli?er, as shown
in Figure 3. The error ampli?er is con?gured so that the
lower of the two noninverting inputs (the SS/TRACK pin
or the 0.6V reference) controls the feedback loop. That
is, when the voltage on the SS/TRACK pin is less than the
0.6V internal reference, the LTC3811 regulates the FB pin
voltage to be approximately equal to the SS/TRACK pin
voltage instead of the internal 0.6V reference. This allows
the user to connect a capacitor from the SS/TRACK pin to
SGND to program the soft-start of the power supply output.
An internal 2.5μA current source charges this capacitor,
creating a voltage ramp on the SS/TRACK pin. As the SS/
TRACK pin voltage rises from 0V to 0.6V, the output volt-
age, V OUT , rises smoothly from 0V to its ?nal value. Once
the soft-start interval is over, the internal 2.5μA current
source will continue to charge the SS/TRACK capacitor
up to a maximum voltage equal to INTV CC .
Alternately, the SS/TRACK pin can be used to force the
start-up of V OUT to track the voltage of another supply.
Typically, this requires connecting the SS/TRACK pin to
an external divider from the other supply to ground (see
Applications Information).
R DS(ON) for the measured V GS , and verify your thermal
calculations by measuring the component temperatures
using an infrared camera.
On/Off Control Using the RUN Pin
The two channels of the LTC3811 can be independently
turned on and off using the RUN1 and RUN2 pins. Pull-
ing either of these pins low shuts down the main control
INTV CC
Q2 Q4
2.5μA
INTV CC
Q3
INTV CC
V FB
SS/TRACK
loop for that channel. Pulling both pins low disables both
controllers and most of the internal circuitry, including the
DRV CC low dropout regulator (LDO). In shutdown mode
0.6V
Q1 Q5
SHDN
M1
(both RUN pins low) the LTC3811 typically draws only
20μA of current.
3811 F03
Figure 3. Simpli?ed LTC3811 Error Ampli?er Input Stage
3811f
17
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| LTC3812EFE5#PBF | 制造商:Linear Technology 功能描述: |
| LTC3812EFE-5#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 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:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LTC3812EFE-5#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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) |
| LTC3812IFE-5#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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) |
| LTC3812IFE-5#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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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