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| 型号： | ADM1170-2AUJZ-RL7 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 11/16页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR HOTSWAP 16.5V TSOT-23-8 |
| 产品培训模块： | Hot Swap Design |
| 标准包装： | 1 |
| 类型： | 热交换控制器 |
| 应用： | 通用 |
| 内部开关： | 无 |
| 电源电压： | 2.7 V ~ 16.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | SOT-23-8 薄型，TSOT-23-8 |
| 供应商设备封装： | TSOT-23-8 |
| 包装： | 标准包装 |
| 产品目录页面： | 792 (CN2011-ZH PDF) |
| 配用： | EVAL-ADM1170EBZ-ND - BOARD EVALUATION FOR ADM1170 |
| 其它名称： | ADM1170-2AUJZ-RL7DKR |
Data Sheet
THEORY OF OPERATION
Many systems require the insertion or removal of circuit boards
to live backplanes. During this event, the supply bypass and hold-
up capacitors can require substantial transient currents from the
backplane power supply as they charge. These currents can
cause permanent damage to connector pins or undesirable glitches
and resets to the system.
The ADM1170 is intended to control the powering of a system
(on and off) in a controlled manner, allowing the board to be
removed from, or inserted into, a live backplane by protecting it
from excess currents. The ADM1170 can reside either on the
backplane or on the removable board.
OVERVIEW
The ADM1170 operates over a supply range of 2.7 V to 16.5 V.
As the supply voltage is coming up, an undervoltage lockout
circuit checks if sufficient supply voltage is present for proper
operation. During this period, the FET is held off by the GATE
pin being held to GND. When the supply voltage reaches a level
above UVLO and the ON (ON-CLR) pin is high, an initial timing
cycle ensures that the board is fully inserted in the backplane
before turning on the FET. The TIMER pin capacitor sets the
periods for all of the TIMER pin functions. After the initial
timing cycle, the ADM1170 monitors the inrush current
through an external sense resistor. Overcurrent conditions are
actively limited to 50 mV/R SENSE for the circuit breaker timer
limit. The ADM1170-1 automatically retries after a current limit
fault and the ADM1170-2 latches off. The retry duty cycle on
the ADM1170-1 timer function is limited to 3.8% for FET
cooling.
UVLO
If the V CC supply is too low for normal operation, an under-
voltage lockout circuit holds the ADM1170 in reset. The GATE
pin is held to GND during this period. When the supply reaches
ADM1170
delay time at card insertion. If using a short pin system to
enable the device, a pull-down resistor should be used to hold
the device prior to insertion.
GATE
Gate drive for the external N-channel MOSFET is achieved
using an internal charge pump. The gate driver consists of a
12 μA pull-up from the internal charge pump. There are various
pull-down devices on this pin. At a hotswap condition the board
is hot inserted to the supply bus. During this event, it is possible
for the external FET GATE capacitance to be charged up by the
sudden presence of the supply voltage. This can cause
uncontrolled inrush currents. An internal strong pull-down
circuit holds GATE low while in UVLO. This reduces current
surges at insertion. After the initial timing cycle, the GATE is
then pulled high. During an overcurrent condition, the
ADM1170 servos the GATE pin in an attempt to maintain a
constant current to the load until the circuit breaker timeout
completes. In the event of a timeout, the GATE pin abruptly
shuts down using the 4 mA pull-down device. Care must be
taken not to load the GATE pin resistively because this reduces
the gate drive capability.
CURRENT LIMIT FUNCTION
The ADM1170 features a fast response current control loop that
actively limits the current by reducing the gate voltage of the
external FET. This current is measured by monitoring the
voltage drop across an external sense resistor. The ADM1170
tries to regulate the gate of the FET to achieve a 50 mV voltage
drop across the sense resistor.
CALCULATING THE CURRENT LIMIT
The sense resistor connected between SENSE+ and the SENSE?
pin is used to determine the nominal fault current limit. This is
given by the following equation:
this UVLO voltage, the ADM1170 starts when the ON (ON-CLR)
pin condition is satisfied.
ON (ON-CLR) PIN
The ON (ON-CLR) pin is the enable pin. It is connected to a
comparator that has a low-to-high threshold of 1.3 V with 80 mV
ILIMIT NOM = VCB NOM / RSENSE NOM
The minimum load current is given by Equation 2
ILIMIT MIN = VCB MIN /RSENSE MAX
The maximum load current is given by Equation 3.
ILIMIT M A X = VCB MAX / RSENSE MIN
(1)
(2)
(3)
hysteresis and a glitch filter. The ADM1170 is reset when the
ON (ON-CLR) pin is low. When the ON (ON-CLR) pin is high,
the ADM1170 is enabled. A rising edge on this pin has the
added function of clearing a fault and restarting the device on
the latched off model, the ADM1170-2 . A low input on the ON
(ON-CLR) pin turns off the external FET by pulling the GATE
pin to ground and resets the timer. An external resistor divider at
the ON (ON-CLR) pin can be used to program an undervoltage
lockout value higher than the internal UVLO circuit. There is a
glitch filter delay of approximately 3 μs on rising allowing the
addition of an RC filter at the ON (ON-CLR) pin to increase the
For proper operation, the minimum current limit must exceed
the circuit maximum operating load current with margin. The
sense resistor power rating must exceed
( VCB MAX ) 2 / RSENSE MIN
CIRCUIT BREAKER FUNCTION
When the supply experiences a sudden current surge, such as a
low impedance fault on load, the bus supply voltage can drop
significantly to a point where the power to an adjacent card is
affected, potentially causing system malfunctions. The
ADM1170 limits the current drawn by the fault by reducing the
Rev. A | Page 11 of 16
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADM1171 | 制造商:AD 制造商全称:Analog Devices 功能描述:2.7 V to 16.5 V Hot Swap Controller with Current Sense Output |
| ADM1171-1AUJ | 制造商:Analog Devices 功能描述:ADI HOT SWAP CONTROLLER - Bulk |
| ADM1171-1AUJZ-RL7 | 功能描述:IC CTRLR HOTSWAP 16.5V TSOT-23-8 RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:119 系列:- 类型:热交换控制器 应用:通用型，PCI Express? 内部开关:无 电流限制:- 电源电压:3.3V，12V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:80-TQFP 供应商设备封装:80-TQFP（12x12） 包装:托盘 产品目录页面:1423 (CN2011-ZH PDF) |
| ADM1171-2AUJ | 制造商:Analog Devices 功能描述:ADI HOT SWAP CONTROLLER - Bulk |
| ADM1171-2AUJZ-RL7 | 功能描述:IC CTRLR HOTSWAP 16.5V TSOT-23-8 RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 标准包装:50 系列:- 类型:热交换控制器 应用:-48V 远程电力系统，AdvancedTCA ? 系统，高可用性 内部开关:无 电流限制:可调 电源电压:11.5 V ~ 14.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-MSOP 包装:管件 |
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