Motore di ricerca datesheet componenti elettronici
  Italian  ▼
ALLDATASHEETIT.COM

X  

ADM1170-2AUJZ-RL7 Scheda tecnica(PDF) 11 Page - Analog Devices

Il numero della parte ADM1170-2AUJZ-RL7
Spiegazioni elettronici  1.6 V to 16.5 V Hot Swap Controller with Soft Start
Download  16 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Produttore elettronici  AD [Analog Devices]
Homepage  http://www.analog.com
Logo AD - Analog Devices

ADM1170-2AUJZ-RL7 Scheda tecnica(HTML) 11 Page - Analog Devices

Back Button ADM1170-2AUJZ-RL7 Datasheet HTML 7Page - Analog Devices ADM1170-2AUJZ-RL7 Datasheet HTML 8Page - Analog Devices ADM1170-2AUJZ-RL7 Datasheet HTML 9Page - Analog Devices ADM1170-2AUJZ-RL7 Datasheet HTML 10Page - Analog Devices ADM1170-2AUJZ-RL7 Datasheet HTML 11Page - Analog Devices ADM1170-2AUJZ-RL7 Datasheet HTML 12Page - Analog Devices ADM1170-2AUJZ-RL7 Datasheet HTML 13Page - Analog Devices ADM1170-2AUJZ-RL7 Datasheet HTML 14Page - Analog Devices ADM1170-2AUJZ-RL7 Datasheet HTML 15Page - Analog Devices Next Button
Zoom Inzoom in Zoom Outzoom out
 11 / 16 page
background image
ADM1170
Rev. 0 | Page 11 of 16
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/RSENSE 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 VCC 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
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
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
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:
ILIMITNOM = VCBNOM/RSENSENOM
(1)
The minimum load current is given by Equation 2
ILIMITMIN = VCBMIN/RSENSEMAX
(2)
The maximum load current is given by Equation 3.
ILIMITMAX = VCBMAX/RSENSEMIN
(3)
For proper operation, the minimum current limit must exceed
the circuit maximum operating load current with margin. The
sense resistor power rating must exceed
(VCBMAX)2/RSENSEMIN
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


Codice articolo simile - ADM1170-2AUJZ-RL7

Produttore elettroniciIl numero della parteScheda tecnicaSpiegazioni elettronici
logo
Analog Devices
ADM1170 AD-ADM1170_15 Datasheet
248Kb / 16P
   1.6 V to 16.5 V Hot Swap Controller with Soft Start
REV. A
More results

Descrizione simile - ADM1170-2AUJZ-RL7

Produttore elettroniciIl numero della parteScheda tecnicaSpiegazioni elettronici
logo
Analog Devices
ADM1170 AD-ADM1170_15 Datasheet
248Kb / 16P
   1.6 V to 16.5 V Hot Swap Controller with Soft Start
REV. A
ADM1172 AD-ADM1172 Datasheet
228Kb / 16P
   2.7 V to 16.5 V Hot Swap Controller with Power-Fail Comparator
REV. 0
ADM1171 AD-ADM1171 Datasheet
255Kb / 16P
   2.7 V to 16.5 V Hot Swap Controller with Current Sense Output
REV. 0
ADM1171 AD-ADM1171_15 Datasheet
243Kb / 16P
   2.7 V to 16.5 V Hot Swap Controller with Current Sense Output
REV. A
ADM1172 AD-ADM1172_15 Datasheet
264Kb / 16P
   2.7 V to 16.5 V Hot Swap Controller with Power-Fail Comparator
REV. A
ADM1177 AD-ADM1177 Datasheet
203Kb / 16P
   Hot Swap Controller and Digital Power Monitor with Soft-Start Pin
Rev. PrD May 2006
ADM1177 AD-ADM1177_15 Datasheet
583Kb / 24P
   Hot Swap Controller and Digital Power Monitor with Soft Start Pin
REV. C
ADM1070 AD-ADM1070 Datasheet
367Kb / 16P
   -48 V Hot Swap Controller
REV. 0
ADM1070 AD-ADM1070_15 Datasheet
341Kb / 16P
   48 V Hot Swap Controller
REV. 0
logo
Texas Instruments
TPS2391DGKR TI-TPS2391DGKR Datasheet
653Kb / 21P
[Old version datasheet]   SIMPLE -48-V HOT SWAP CONTROLLER
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16


Scheda tecnica Scarica

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEETIT.COM
Lei ha avuto il aiuto da alldatasheet?  [ DONATE ] 

Di alldatasheet   |   Richest di pubblicita   |   contatti   |   Privacy Policy   |   scambio Link   |   Ricerca produttore
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com