收藏本站
NCP3125
Overcurrent Threshold Setting
NCP3125 overcurrent threshold can be set from 50 mV to
0.9 V
COMP
BG
TG
550 mV, by adding a resistor (R SET ) between ISET and
GND. During a short period of time following V IN rising
over UVLO threshold, an internal 10 m A current (I OCSET ) is
sourced from the ISET pin, creating a voltage drop across
R SET . The voltage drop is compared against a stepped
internal voltage ramp. Once the internal stepped voltage
reaches the R SET voltage, the value is stored internally until
power is cycled. The overall time length for the OC setting
procedure is approximately 9 ms. Connecting an R SET
resistor between ISET and GND, the programmed threshold
will be:
Figure 17. Enable/Disable Driver State Diagram
External Soft ? Start
I OCth +
I OCSET * R SET
R DS(on)
3 4.2 A +
10 m A * 21 k W
50 m W
(eq. 1)
The NCP3125 features an external soft ? start function,
which reduces inrush current and overshoot of the output
voltage. Soft ? start is achieved by using the internal current
source of 10.5 m A (typ), which charges the external
integrator capacitor of the OTA. Figure 18 is a typical
soft ? start sequence. The sequence begins once V IN and
V BST surpass their UVLO thresholds and OCP
programming is complete. The current sourced out of the
COMP pin continually increases the voltage until regulation
is reached. Once the voltage reaches 400 mV logic is
enabled. When the voltage exceeds 900 mV, switching
begins. Current is sourced out of the COMP pin, placing the
regulator into open loop operation until 800 mV is sensed at
the FB pin. Once 800 mV is sensed at the FB pin, open loop
operation ends and closed loop operation begins. In closed
loop operation, the OTA is capable of sourcing and sinking
I OCSET = Sourced current
I OCth = Current trip threshold
R DS(on) = On resistance of the low side MOSFET
R SET = Current set resistor
The R SET values range from 5 k W to 55 k W . If R SET is not
connected, the device switches the OCP threshold to a fixed
375 mV value. An internal safety clamp on ISET is triggered
as soon as ISET voltage reaches 700 mV, enabling the
375 mV fixed threshold and ending the OCP setting period.
The current trip threshold tolerance is ± 25 mV. The
accuracy is best at the highest set point (550 mV). The
accuracy will decrease as the set point decreases. MOSFET
tolerances with temperature and input voltage will vary the
over current set threshold operating point. A graph of the
typical current limit set thresholds at 4.5 V and 12 V is
shown in Figure .
120 m A.
4.2 V
3.85 V
7
6.5
VCC
6
COMP
VFB
BG
TG
0.9 V
5.5
5
4.5
4
3.5
12 V
5V
BG Comparator
DAC Voltage
50 mV
500 mV
3
2.5
BG Comparator Output
2
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21
Vout
UVLO
POR Current Soft ? Start Normal Operation
Delay Trip Set COMP
Delay
UVLO
R SET (k W )
Figure 19. R SET Value for Output Current
Figure 18. Soft ? Start Sequence
http://onsemi.com
8
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
A9AAT-1304F FLEX CABLE - AFE13T/AF13/AFE13T
MAX6006BESA+ IC VREF SHUNT PREC 1.25V 8-SOIC
A9CAA-0802E FLEX CABLE - AFK08A/AE08/AFH08T
A9AAT-2203E FLEX CABLE - AFH22T/AE22/AFH22T
RE-1512S/H CONV DC/DC 1W 15VIN 12VOUT
NCP3127AGEVB BOARD EVALUATION NCP3127
A9CAG-0603F FLEX CABLE - AFG06G/AF06/AFE06T
A9BBG-0204F FLEX CABLE - AFF02G/AF02/AFF02G
相关代理商/技术参数
NCP3125CRAGEVB 功能描述:电源管理IC开发工具 NCP3125 Ceramic Eval Board RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V
NCP3126ADR2G 功能描述:直流/直流开关转换器 3A PWM Switching Buck Regulator RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT
NCP3126AGEVB 功能描述:电源管理IC开发工具 NCP3126 EVB RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V
NCP3126CRAGEVB 功能描述:电源管理IC开发工具 NCP3126 CERAMIC EVB RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V
NCP3127ADR2G 功能描述:直流/直流开关转换器 2A PWM Switching Buck Regulator RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT
NCP3127AGEVB 功能描述:电源管理IC开发工具 NCP3127 EVALUATION BOARD RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V
NCP3127CRAGEVB 功能描述:电源管理IC开发工具 NCP3127 CERAMIC EVB RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V
NCP3155ADR2G 功能描述:直流/直流开关调节器 BUCK CONTROLLER RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5