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参数资料
| 型号： | LTC3862HFE#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | DUAL SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO24 |
| 封装： | 4.40 MM, LEAD FREE, PLASTIC, TSSOP-24 |
| 文件页数： | 6/40页 |
| 文件大小： | 613K |
| 代理商： | LTC3862HFE#PBF |
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LTC3862
14
3862fb
OPERATION
To prevent the maximum junction temperature from be-
ing exceeded, the input supply current to the IC should
be checked when operating in continuous mode (heavy
load) at maximum VIN. A tradeoff between the operating
frequency and the size of the power MOSFETs may need
to be made in order to maintain a reliable junction tem-
perature. Finally, it is important to verify the calculations
by performing a thermal analysis of the nal PCB using
an infrared camera or thermal probe. As an option, an
exernal regulator shown in Figure 3 can be used to reduce
the total power dissipation on the IC.
Thermal Shutdown Protection
In the event of an overtemperature condition (external
or internal), an internal thermal monitor will shut down
the gate drivers and reset the soft-start capacitor if the
die temperature exceeds 170°C. This thermal sensor
has a hysteresis of 10°C to prevent erratic behavior at
hot temperatures. The LTC3862’s internal thermal sen-
sor is intended to protect the device during momentary
overtemperature conditions. Continuous operation above
the specied maximum operating junction temperature,
however, may result in device degradation.
Operation at Low Supply Voltage
The LTC3862 has a minimum input voltage of 4V, making
it a good choice for applications that experience low sup-
ply conditions. The gate driver for the LTC3862 consists
of PMOS pull-up and NMOS pull-down devices, allowing
the full INTVCC voltage to be applied to the gates during
power MOSFET switching. Nonetheless, care should be
taken to determine the minimum gate drive supply voltage
(INTVCC) in order to choose the optimum power MOSFETs.
Important parameters that can affect the minimum gate
drive voltage are the minimum input voltage (VIN(MIN)),
the LDO dropout voltage, the QG of the power MOSFETs,
and the operating frequency.
If the input voltage VIN is low enough for the INTVCC LDO
to be in dropout, then the minimum gate drive supply
voltage is:
VINTVCC = VIN(MIN) – VDROPOUT
The LDO dropout voltage is a function of the total gate
drive current and the quiescent current of the IC (typically
3mA). A curve of dropout voltage vs output current for the
LDO is shown in Figure 2. The temperature coefcient of
the LDO dropout voltage is approximately 6000ppm/°C.
The total Q-current (IQ(TOT)) owing in the LDO is the sum
of the controller quiescent current (3mA) and the total gate
charge drive current.
IQ(TOT) = IQ + QG(TOT) f
After the calculations have been completed, it is impor-
tant to measure the gate drive waveforms and the gate
driver supply voltage (INTVCC to PGND) over all operating
conditions (low VIN, nominal VIN and high VIN, 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 RDS(ON) for the measured
VGS, and verify your thermal calculations by measuring
the component temperatures using an infrared camera
or thermal probe.
INTVCC LOAD (mA)
0
DROPOUT
VOL
TAGE
(mV)
600
800
1000
30
50
3862 F02
400
200
0
10
20
40
1200
1400
1600
85°C
25°C
–40°C
125°C
150°C
Figure 2. INTVCC LDO Dropout Voltage vs Current
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相关代理商/技术参数 |
参数描述 |
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| LTC3862HGN#PBF | 功能描述:IC REG CTRLR BST PWM CM 24-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: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 |
| LTC3862HGN#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 24-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: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 |
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| LTC3862HGN-1#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 24-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: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 |
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