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参数资料
| 型号： | LTC3811EUHF#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 16/48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)
be increased to 10μF. Because of the high peak current
capability of the gate driver, it is essential that this capacitor
be placed as close as possible to DRV CC and PGND pins,
and on the same PCB layer as the IC.
The INTV CC pin supplies power to all of the low voltage
analog circuitry and is electrically isolated from DRV CC . The
INTV CC supply is normally derived from DRV CC through
an RC ?lter, in order to prevent gate driver supply noise
from coupling into sensitive analog control circuitry. Typi-
cal values for this RC ?lter consist of a 1 Ω resistor from
DRV CC to INTV CC and a 0.1μF low ESR ceramic capacitor
from INTV CC to SGND. The INTV CC capacitor should be
placed as close as possible to the INTV CC and SGND pins
and on the same PCB layer as the IC.
A third power supply pin, EXTV CC , serves as an auxiliary
input for applications where the power dissipation in the
internal LDO is excessive, or where maximum ef?ciency
is essential. This con?guration is shown in Figure 2. When
the EXTV CC pin is left open or is connected to a voltage
less than 4.5V, the internal 6V LDO supplies DRV CC power
from V IN . If EXTV CC is tied to an external power supply
greater than 4.5V, however, the 6V LDO is turned off and
power is supplied to DRV CC through a 5 Ω PMOS switch
from EXTV CC . For 4.5V < EXTV CC < 7V this PMOS switch
is on and DRV CC is approximately equal to EXTV CC . Using
the EXTV CC pin allows the gate driver and control power to
be derived from a high ef?ciency external source, dramati-
cally reducing power dissipation on the IC.
Using an External 5V Supply to Measure Dynamic
Quiescent Current
When a voltage above 4.5V is applied to the EXTV CC pin, the
internal LDO in the LTC3811 is switched off and the power
is supplied by the external 5V power supply as shown in
Figure 2. Under these conditions, the quiescent current
at the V IN pin of the IC is very low (less than 1mA), and
most of the current required to power the analog control
circuitry and the gate drivers ?ows into the EXTV CC pin. As
a result, this auxiliary supply can be used as a diagnostic
tool in order to measure the total current for thermal
calculations. In order to match the actual condition when
the internal LDO is on, the voltage applied to EXTV CC when
the measurements are taken should be 6V (the same as
the regulated LDO output voltage).
Once the total quiescent current for the application is
known, the power dissipation, P D , on the IC will be ap-
proximately I EXTVCC times V IN , since the gate drive current
and control circuitry quiescent current would be required
to ?ow through the V IN pin. The junction temperature of
the IC can then be estimated using the following well-
known formula:
T J = T A + (P D ? R θ JA )
If the maximum junction temperature is close to the Abso-
lute Maximum Rating for the particular device being used,
the use of an auxiliary supply and the EXTV CC pin may be
required. Alternatively, lower gate charge MOSFETs should
be used or the switching frequency should be reduced.
V IN
V IN
Operation at Low Supply Voltage
AUX 5V
SUPPLY
EXTV CC
4.5V
+
–
6V
LDO
The LTC3811 control circuit has a minimum input volt-
age of 4.5V, making it a good choice for applications that
experience low supply conditions. However, care should
DRV CC
GATE DRIVER SUPPLY
be taken to determine the minimum gate drive supply
voltage in order to choose the optimum power MOSFETs.
INTV CC
ANALOG SUPPLY
Important parameters that can affect the minimum gate
SGND
BIAS
V FB
SS/TRACK
0.600V
EA
drive voltage are the minimum input voltage (V IN ), the
LDO dropout voltage, and the EXTV CC supply voltage, if
an external gate drive supply is being used.
3811 F02
Figure 2. Supplying Power to the LTC3811 from EXTV CC
3811f
16
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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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