ISL6121
Implementing Autoreset on the ISL6121
Hot Swap Controller.
Description of Operation
Abstract
In applications where the cost, complexity or requirement for
a system controller is avoided and an autonomous power
control function is desired, a device that can monitor and
Rpu = 2k
VIN
FLTn
ENABLE
protect against excessive current failures is needed. This
tech brief shows how to implement such an autonomous
C = 0.1 μ F
GND
ISL6121H
controller using the ISL6121HIB. This application works only
with the ‘H’ version of this device. The ‘H’ version refers to
the enable function being asserted upon a high input.
Introduction
The ISL6118, ISL6119 and ISL6121 are all 2.5V to 5V power
supply controllers, each having a different level of current
regulation (CR). The ISL6118 and ISL6119 have 2
independent controllers with CR levels of 0.6A and 1.0A
respectively whereas the ISL6121 is a single supply
controller with a 2A CR level. Each of these devices features
integrated power switch(es) for power control. Each switch
is driven by a constant current source giving a controlled
ramp up of the output voltage. This provides a soft start
turn-on eliminating bus voltage drooping caused by in-rush
current while charging heavy load capacitances. The
independent enabling inputs and fault reporting outputs for
each channel are available and necessary for the
autonomous autoreset application.
The undervoltage (UV) feature prevents turn-on of the
outputs unless the ENABLE pin and VIN are > 2.5V. During
initial turn-on the ISL6121 prevents fault reporting by
blanking the fault signal. Rising and falling outputs are
current-limited voltage ramps so that both the inrush
current and voltage slew rate are limited, independent of
load. This reduces supply droop due to surge and
eliminates the need for external EMI filters. During
operation, once an OC condition is detected the
appropriate output is current limited to the appropriate level
FIGURE 18.
Initially as voltage is applied to VIN, the pull up resistor (Rpu)
provides for pull up to VIN on both the ENABLE pin asserting
the output once VIN > 2.5V and on the FLTn pin. Once turned
on and an overcurrent (OC) condition occurs the IC provides
CR protection for 10ms and then the FLTn pin pulls low through
Rpu and also pulling the ENABLE low thus resetting the device
fault condition. At this time the Rpu charges the cap and the
voltage on the ENABLE / FLTn node rises until the ENABLE >
2.0 and the output is asserted on once again. This automatic
reset cycle will continue until the OC fault no longer exists on
the output. After several seconds in this mode of operation the
IC thermal protection invokes adjusting the timing of the on-off
cycle to prevent excessive thermal dissipation in the power
switch protecting itself and surrounding circuitry. See Figure 19
for operation waveform.
.
VIN / FLTn 5V / DIV
VOUT 2V / DIV
0V
IOUT 1A / DIV
for 10ms to allow transient conditions to pass. If still in
current limit after the current limit period has elapsed, the
output is latched off and the fault is reported by pulling the
corresponding FAULT low. The FAULT signal is latched low
until reset by the ENABLE signal being de-asserted at
which time the FAULT signal will clear.
It is this described sequence of events that allows for the
autoreset function to be implemented in a cost efficient
manner requiring the addition of only an RC network per
channel to the typical application.
Figure 18 illustrates the RC network needed with suggested
component values and the configuration of the relevant pins
for each autoreset channel.
0A
FIGURE 19. AUTO RESET OPERATION
Applications
? USB
? 2.5V to 5V up to 10W power port protection
4ms/DIV
10
FN9004.2
November 12, 2004
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相关代理商/技术参数
ISL6121HEVAL1 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Single Supply Integrated Current Limiting Controller
ISL6121HIB 功能描述:IC CTRLR POWER SUPPLY SGL 8-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 电源控制器,监视器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 应用:多相控制器 输入电压:- 电源电压:9 V ~ 14 V 电流 - 电源:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:40-WFQFN 裸露焊盘 供应商设备封装:40-TQFN-EP(5x5) 包装:带卷 (TR)
ISL6121HIB-T 功能描述:IC CTRLR POWER SUPPLY SGL 8-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 电源控制器,监视器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 应用:多相控制器 输入电压:- 电源电压:9 V ~ 14 V 电流 - 电源:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:40-WFQFN 裸露焊盘 供应商设备封装:40-TQFN-EP(5x5) 包装:带卷 (TR)
ISL6121HIBZA 功能描述:IC SUPPLY/CURR LIMIT CTRLR 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 电源控制器,监视器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 应用:多相控制器 输入电压:- 电源电压:9 V ~ 14 V 电流 - 电源:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:40-WFQFN 裸露焊盘 供应商设备封装:40-TQFN-EP(5x5) 包装:带卷 (TR)
ISL6121HIBZA-T 功能描述:IC SUPPLY/CURR LIMIT CTRLR 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 电源控制器,监视器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 应用:多相控制器 输入电压:- 电源电压:9 V ~ 14 V 电流 - 电源:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:40-WFQFN 裸露焊盘 供应商设备封装:40-TQFN-EP(5x5) 包装:带卷 (TR)
ISL6121LIB 功能描述:IC CTRLR POWER SUPPLY SGL 8-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 电源控制器,监视器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 应用:多相控制器 输入电压:- 电源电压:9 V ~ 14 V 电流 - 电源:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:40-WFQFN 裸露焊盘 供应商设备封装:40-TQFN-EP(5x5) 包装:带卷 (TR)
ISL6121LIB-T 功能描述:IC SUPPLY/CURR LIMIT CTRLR 8SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 电源控制器,监视器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 应用:多相控制器 输入电压:- 电源电压:9 V ~ 14 V 电流 - 电源:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:40-WFQFN 裸露焊盘 供应商设备封装:40-TQFN-EP(5x5) 包装:带卷 (TR)
ISL6121LIBZA 功能描述:IC SUPPLY/CURR LIMIT CTRLR 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 电源控制器,监视器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 应用:多相控制器 输入电压:- 电源电压:9 V ~ 14 V 电流 - 电源:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:40-WFQFN 裸露焊盘 供应商设备封装:40-TQFN-EP(5x5) 包装:带卷 (TR)