参数资料
型号: LTC3862IGN#TRPBF
厂商: Linear Technology
文件页数: 16/42页
文件大小: 0K
描述: IC REG CTRLR BST PWM CM 24-SSOP
标准包装: 2,500
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:
升压:
回扫:
反相:
倍增器:
除法器:
Cuk:
隔离:
工作温度: -40°C ~ 125°C
封装/外壳: 24-SSOP(0.154",3.90mm 宽)
包装: 带卷 (TR)
LTC3862
OPERATION
Operation of the RUN Pin
The control circuitry in the LTC3862 is turned on and
off using the RUN pin. Pulling the RUN pin below 1.22V
forces shutdown mode and releasing it allows a 0.5μA
current source to pull this pin up, allowing a “normally
on” converter to be designed. Alternatively, the RUN pin
can be externally pulled up or driven directly by logic.
Care must be taken not to exceed the absolute maximum
rating of 8V for this pin.
V IN
INTERNAL 5V
0.5μA
RUN
10V 1.22V
SGND
4.5μA
+
LTC3862
BIAS AND
START-UP
CONTROL
RUN
COMPARATOR
I IN = OUT OUT
CONTROL
+
10V
1.22V
The comparator on the RUN pin can also be used to sense
the input voltage, allowing an undervoltage detection
circuit to be designed. This is helpful in boost converter
applications where the input current can reach very high
levels at low input voltage:
I ? V
V IN ? η
The 1.22V input threshold of the RUN comparator is derived
from a precise bandgap reference, in order to maximize
the accuracy of the undervoltage-sensing function. The
RUN comparator has 80mV built-in hysteresis. When
the voltage on the RUN pin exceeds 1.22V, the current
sourced into the RUN pin is switched from 0.5μA to 5μA
current. The user can therefore program both the rising
threshold and the amount of hysteresis using the values
of the resistors in the external divider, as shown in the
following equations:
3862 F05a
Figure 5a. Using the RUN Pin for a “Normally On” Converter
V IN LTC3862
INTERNAL 5V
EXTERNAL
LOGIC
0.5μA
4.5μA
RUN
BIAS AND
START-UP
CONTROL
RUN
COMPARATOR
SGND
3862 F05b
Figure 5b. On/Off Control Using External Logic
V IN ( ON ) = 1 . 22 V ? 1 + A ? – 0 . 5 μ ? R A
? R ?
? R B ?
V IN
INTERNAL 5V
LTC3862
V IN ( OFF ) = 1.. 22 V ? 1 + A ? – 5 μ ? R A
? R ?
? R B ?
Several of the possible RUN pin control techniques are
illustrated in Figure 5.
R A
R B
0.5μA
RUN
10V
SGND
4.5μA
1.22V
+
BIAS AND
START-UP
CONTROL
RUN
COMPARATOR
Frequency Selection and the Phase Lock Loop
The selection of the switching frequency is a tradeoff
between efficiency and component size. Low frequency
operation increases efficiency by reducing MOSFET
switching losses, but requires a larger inductor and output
capacitor to maintain low output ripple.
3862 F05c
Figure 5c. Programming the Input Voltage Turn-On and Turn-Off
Thresholds Using the RUN Pin
3862fc
16
For more information www.linear.com/LTC3862
相关PDF资料
PDF描述
H2AAT-10102-Y8-ND JUMPER-H1502TR/A3048Y/H1502TR 2"
LTC3785EUF-1#PBF IC REG CTRLR BST PWM VM 24-QFN
RLB9012-391KL INDUCTOR HI CURRENT RADIAL 390UH
LTC1735IGN-1#TRPBF IC REG CTRLR BUCK PWM CM 16-SSOP
RBA31DCBS CONN EDGECARD 62POS R/A .125 SLD
相关代理商/技术参数
参数描述
LTC3862IUH#PBF 功能描述:IC REG CTRLR BST PWM CM 24-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:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 升压:是 回扫:是 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:8-TSSOP(0.173",4.40mm 宽) 包装:带卷 (TR)
LTC3862IUH#TRPBF 功能描述:IC REG CTRLR BST PWM CM 24-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)
LTC3862IUH-1#PBF 功能描述:IC REG CTRLR BST PWM CM 24-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)
LTC3862IUH-1#TRPBF 功能描述:IC REG CTRLR BST PWM CM 24-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: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
LTC3862IUH-2#PBF 功能描述:IC REG CTRLR BST PWM CM 24-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)