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ADM1203 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer ADM1203
Beschreibung Simple Tracker
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 8 Seiten
ADM1203 Datasheet, Funktion
Preliminary Technical Data
FEATURES
Enables Power Supply Tracking of multiple Supplies
Monitors Current on Supply being Tracked
Up/Down Tracking limits Supply Differences to ~100mV
Capacitor Adjustable Slew Rate
On Board Charge Pump Fully enhances FET
Ability to Track Down Supplies (ADM1203-1/3)
Emergency Shutdown Feature (ADM1203-2/4)
Auto retry after Current Fault (ADM1203-1/2)
Latch off after Current Fault (ADM1203-3/4)
Packaged in tiny 8-Lead TSOT Package
APPLICATIONS
Multi-Voltage Supply Rail Tracker
Telecoms and Datacom s Systems
Multi voltage Network Processors , FPGAs, ASICs, DSPs
PC/Server Applications
GENERAL DESCRIPTION
The ADM1203 is a cascadable Simple Tracker TM device which
ensures that voltage rails track within ~100mV of each other in
multi supply systems. Any number of these devices can be
cascaded to form a multi supply tracking solution.
The ADM1203 requires 2.7V to 16.5V on its Vcc pin to operate.
An on-board charge pump generates a high voltage GATE drive
to fully enhance FETs in the power path.
The Slew Rate of the ramp is adjustable via an external capacitor
on the CSLEW pin and can be programmed from 100V/s to
1000V/s. When multiple devices are cascaded the CSLEW pin of
each subsequent device should be tied to the output rail of the
previous device to ensure that supply will track up and down
with the previous supply.
The ADM1203 is offered in four variants. The ADM1203-1/3
features an UP/DOWNb pin and the ADM1203-2/4 features an
Up/STOPb pin. The ADM1203-1/2 features an auto retry on
current RS fault and the ADM1203-3/4 latches off. For all
devices, a high level on the input will initiate tracking power up
sequence. A low on the UP/DOWNb pin of the ADM1203-1/3
will initiate a tracking down of the supply rails, while a low on
the UP/STOPb pin of the ADM1203-2/4 will initiate an
emergency fast shutdown of all supply rails simultaneously.
The ADM1203 features a current sense comparator, which
monitors for an over current condition on the supply. In the
event of an over current condition, a fault is flagged and the gate
is switched off. The ADM1203-1/2 will auto retry this fault at
Rev. PrD
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
Simple Tracker TM with
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Circuit Breaker
ADM1203
every cycle determined by the capacitor on the TIMER pin and
the ADM1203-3/4 will latch off the gate until the
up/down(stop) pin is toggled.
The ADM1203 is packaged in a tiny 8-pin TSOT package.
Functional Block Diagram
Rs Q1
VIN
VCC RS-
VOUT
UP/DOWN
(ADM1203-1/3)
UP/STOP
(ADM1203-2/4)
CSLEW
CSLEW
CTIMER
CTIMER
VCC
LOGIC
FET
DRIVER
GATE
20nF
SLEW RATE
CONTROL
VOUT
TIMER
CONTROL
GND
ADM1203
Applications Diagram
5VIN
RSENSE
Q1
POWER ON/OFF
CSLEW
3.3VIN
Vcc RS-
UP/DOWN
GATE
ADM1203-1 1nF
SLEW
TIMER
CTIMER
VOUTFB
GND
RSENSE
Q1
POWER ON/OFF
2.7VIN
Vcc RS-
UP/DOWN
GATE
ADM1203-1 1nF
SLEW
TIMER
CTIMER
VOUTFB
GND
RSENSE
Q1
POWER ON/OFF
Vcc RS-
UP/DOWN
GATE
ADM1203-1 1nF
SLEW
TIMER
CTIMER
VOUTFB
GND
5VOUT
3.3VOUT
2.7VOUT
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.326.8703 ©©22000053 Analog Devices, Inc. All rights reserved.






ADM1203 Datasheet, Funktion
ADM1203
TIMER FUNCTION
The TIMER pin handles several key functions with an external
capacitor, CTIMER. There are two comparator thresholds:
COMP1 (0.2V) and COMP2 (1.3V). The four timing current
sources are:
5µA pull-up
60µA pull-up
2µA pull-down
100µA pull-down
The 100µA is a non-ideal current source approximating a 7k
resistor below 0.4V.
INITIAL TIMING CYCLE
When the card is being inserted into the bus connector, the
long pins mate first which brings up the supply VIN at time
point 1 of Figure 7. The ADM1203 is in reset mode as the ON
pin is low. GATE is pulled low and the TIMER pin is pulled low
with a 100µA source. At time point 2, the short pin makes
contact and ON is pulled high. At this instant, a start-up check
requires that the supply voltage be above UVLO, the ON pin
beabove1.3Vand the TIMER pin voltage be less than 0.2V.
When these three conditions are fulfilled, the initial cycle
begins and the TIMER pin is pulled high with 5µA. At time
point 3, the TIMER reaches the COMP2 threshold and the first
portion of the initial cycle ends. The 100µA current source then
pulls down the TIMER pin until it reaches 0.2V at time point 4.
The initial cycle delay (time point 2 to time point 4) is related to
CTIMER by equation:
tINITIAL ~= 272.9 x CTIMER ms/uF
(4)
When the initial cycle terminates, a start-up cycle is activated
and the GATE pin ramps high. The TIMER pin continues to be
pulled down towards ground.
Preliminary Technical Data
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VIN
VON
VTIMER
VGATE
VOUT
RE SET
MODE
INITIAL
CYCLE
S TART -UP
CYCLE
NORM AL
CYCLE
Figure 7: Normal Start-up
V IN
VON
VTIMER
VGATE
VOUT
5µA 60µA
100µA
2µA
100µA
VTH
IRSENSE
RESET
MODE
INITIAL
CYCLE
START-UP
CYCLE
NORMAL
CYCLE
Figure 8: Current Limiting at Start-up
Rev. PrD | Page 6 of 8

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