Datasheet ADM1202 Datasheet (Analog Devices)

© 2005

Preliminary Technical Data

FEATURES

Enables Power Supply Tracking of multiple supplies
Up/Down Tracking limits Supply Differences to ~100mV
Capacitor Adjustable Slew Rate
On Board Charge Pump Fully enhances FET
Ability to Track Down Supplies (ADM1202-1)
Emergency Shutdown Feature (ADM1202-2)
In-Built Power Good Detector Circuitry
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 ADM1202 is a cascadable Simple Tracker
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 ADM1202 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 C

pin and can be programmed from 100V/s to

SLEW

1000V/s. When multiple devices are cascaded the C
each subsequent device should be tied to the output rail(V
of the previous device to ensure that supply will track up and
down with the previous supply.

The ADM1202 is offered in two variants. The ADM1202-1
features an UP/DOWNb pin and the ADM1202-2 features an
Up/STOPb pin. For both devices a high level on the this input
will initiate tracking power up sequence. A low on the
UP/DOWNb pin of the ADM1202-1 will initiate a tracking
down of the supply rails, while a low on the UP/STOPb pin of
the ADM1202-2 will initiate an emergency fast shutdown of all
supply rails simultaneously.

Power Fail Detector circuitry is also present. A resistor divider
on the PFI input will dictate what level the ADM1202 registers a
power fail on that supply. When a power fail is detected the
Power Fail Output (PFO) will assert.

The ADM1202 is packaged in a tiny 8-pin TSOT package.

TM

device which

pin of

SLEW

OUTFB

)

Simple Tracker

with Power-Good Comparator

ADM1202

Functional Block Diagram

Q

GATE

1nF

V

OUTFB

PFI

5VOUT

R

1

R

2

3.3VOUT

R

3

R

4

2.8VOUT

R

5

R

6

1

5V POWER GOOD

3.3V POWER GOOD

2.8V POWER GOOD

R

1

R

2

V

IN

UP/DOWN

UP/STOP

POWER ON/OFF

(ADM1202-1)
(ADM1202-2)

C

SLEW

5VIN

3.3VIN

2.8VIN

2.7V - 16V

V

CC

V

CHARGE

FET

PUMP

UP / D OWN
DETECTOR

C

SLEW

PFO

SLEW RATE

CONTROL

POWER FAIL

DETECTOR

GND

LOGIC

ADM1202

FET

DRIVER

Applications Diagram

Q

1

VCC

ADM1202-1

GND

ADM1202-1

GND

ADM1202-1

GND

PFO

GATE

V

PFO

GATE

V

PFO

GATE

V

1nF

OUT

PFI

Q2

1nF

OUT

PFI

Q3

1nF

OUT

PFI

V

cc

UP/DOWN

C

SLEW

VCC

VCC

SLEW

V

cc

UP/DOWN

C

SLEW

V

cc

UP/DOWN

C

SLEW

C

TM

V

OUT

Rev. PrF

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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
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registered trademarks are the property of their respective companies.

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Tel: [phone]
Fax: [phone] © 2004 Analog Devices, Inc. All rights reserved.

www.analog.com

Preliminary Technical Data

ADM1202—SPECIFICATIONS

Table 1. V

Parameter Min Typ Max Units Conditions

VCC Pin

Operating Voltage Range Vcc 2.7 16.5 V
Undervoltage Lockout, V
UVLO Hysteresis 25 mV
Switched Voltage Range 0.65 16.5
Quiesent Current 0.65 1.0

Up/Downb Pin
Input Threshold 0.58 0.6 0.62
Input Threshold Hysteresis 60 mV
Input Current
Power Fail Output, PFO Pin
Internal Pull Up -5
Output Low Voltage 0.4 V Note 1, Iload = 300uA
Power Fail Detector, PFI Pin
PFI Detector Threshold
PFI Detector Hysterisis
PFI Input Current

C

Pin

SLEW

Slew up Current
Slew down Current
Tracking Gain 1 V/V V
Minimum Tracking Voltage 0.1 V
Maximum Tracking voltage Vcc – 0.3 V
Slew Rate

V

Pin

OUTFB

Input Current
Voltage Range 0 Vcc V

GATE Pin

Gate Pullup Current 12
Gate Pulldown Current 12
Gate Pulldown Current 2
GATE Voltage, V
6 8 12 V V
5 6.5 10 V V

NOTES:

1

Asserted when voltage on PFI pin exceeds threshold

= Full Operating Range, TA = -40°C to +85°C, unless otherwise noted.

CC

2.4 2.525 2.65 V Vcc Rising

UVLO

5 6.5 10 V V

GATE

-100 100 nA

0.58 0.6 0.62 V
10 mV

-100 100 nA

-10
10

100 1000 V/s

-10 10

V

mA

V

µA

µA
µA

µA

µA
µA

mA

Rising

SLEW/VOUTFB

Vslew – Vout > 100mV
Vout – Vslew > 100mV
ADM1202-2 only –vgate = 3.0V

– VCC; VCC = 2.7V

GATE

– VCC; VCC = 5.0V

GATE

– VCC; VCC = 16.5V

GATE

Absolute Maximum Ratings

Table 2. ADM1202 Absolute Maximum Ratings

Parameter
VCC Pin 20V
PFI Pin 20V
UP/DOWNb, UP/STOPb 20V
PFO Pin 20V
C

Pin 20V

SLEW

Gate Pin Vcc + 11V
V

Pin 20V

OUTFB

Power Dissipation TBD
Storage Temperature –65°C to +125°C
Operating Temperature Range –40°C to +85°C
Lead Temperature Range

(Soldering 10 sec)

Rating

300°C

Junction Temperature 150°C

Rev. PrF | Page 2 of 6

Preliminary Technical Data ADM1202

ENABLING A SINGLE SUPPLY

The ADM1202 requires a supply voltage of 2.7V to 16.5V on its
Vcc pin for operation. The device may be powered from the
input supply rail that is being switched or from an auxiliary
supply.

An internal charge pump ensures that the ADM1202 is capable
of fully enhancing an external FET via the GATE pin, turning
on the output. An external capacitor may be required on the
GATE node for stability.

Power up can be externally initiated by driving the
UP/DOWNb (ADM1202-1) or UP/STOPb (ADM1202–2)
logic pin high. A low on this pin will initiate a power down.

The V

A single ADM1202 device may be used where a single supply
rail is required to switch on at a controlled slew rate (see Figure

1). The value of the slew rate capacitor, C
slew rate of the GATE voltage at startup. An internal current

10µA source charges C

the same rate.

3.3VIN

pin monitors the output voltage.

OUTFB

and the GATE voltage is ramped at

SLEW

, will dictate the

SLEW

Q

1

3.3VOUT

5VIN

POWER ON/OFF

3.3VIN

2.8VIN

C

SLEW

VCC

VCC

VCC

ADM1202-1

V

cc

UP/DOWN

C

SLEW

ADM1202-1

V

cc

UP/DOWN

C

SLEW

ADM1202-1

V

cc

UP/DOWN

C

SLEW

GND

GND

GND

PFO

GATE

V

OUT

PFI

PFO

GATE

V

OUT

PFI

PFO

GATE

V

OUT

PFI

Q

1

5VOUT

5V POWER GOOD

1nF

1nF

1nF

R

1

R

2

Q2

Q3

3.3VOUT

R

3

R

4

2.8VOUT

R

5

R

6

3.3V POWER GOO D

2.8V POWER GOO D

ADM1202-2

V

POWER ON/OFF

C

SLEW

cc

UP/STOP

C

SLEW

GND

GATE

V

OUTFB

PFI

PFO

1nF

R

1

R

2

Figure 1. ADM1202 Switching on a Single Supply

MULTI-SUPPLY TRACKING

The primary function of the ADM1202 is to provide a voltage
tracking solution for multiple supply rails. The implementation
in Figure 2 will provide this function. Each voltage rail has its
own ADM1202 device driving a FET.

The UP/DOWNb (ADM1202-1) or UP/STOPb (ADM1202-2)
pins of all devices can be driven by a single logic input which
will initiate a system power-up going high or power-down
going low.

In figure 2, the ADM1202 is configured to control the ramp of
the largest supply first. The output of the first device is
connected to the slew pin on the second device to allow the rate
of the first supply to control the rate of the second and so on.

Figure 2. ADM1202 Solution for Tracking 3 Supplies

A low-to-high transition on the UP/DOWNb or UP/STOPb pin
will initiate turn-on of the supplies. The ADM1202 will begin to
source current into the C

capacitor. The voltages on all

SLEW

GATE pins will begin to rise, or “track” up, at the same rate, as
set by the value of C
100mV of the C

. All supply voltages will remain within

SLEW

voltage until they level off at their full

SLEW

potentials.

A high-to-low on the UP/DOWNb pin of the ADM1202-1 will
initiate a tracking down of the supply rails. The voltages will
attempt to stay with ~100mV of each other assuming the load
current will be sufficient to discharge the capacitors at the
required rate. (See Figure 3.)

A high-to-low on the UP/STOPb pin of the ADM1202-2 will
initiate an emergency fast shutdown of all supply rails
simultaneously. (See Figure 4.) Note that while the pass FETs
will be turned off immediately the actual discharge rate of each
supply rail will depend on the load.

Rev. PrF | Page 3 of 6

ADM1202 Preliminary Technical Data

UP/DOW N

V

cc

3.3V

2.5V

1.5V

OUTPUT

VOLTAGES

Figure 3. ADM1202-1 Power-Up and Power-Down Waveforms

UP/STOP

3.3V

2.5V

1.5V

OUTPUT

VOLTAGES

Figure 4. ADM1202-2 Power-Up and Power-Down Waveforms

PFI/PFO COMPARATOR

R

1

V

REF

PFI

R

2

+

-

5uA

PFO

ADM1202

Figure 5. ADM1202 Internal Power Fail Detector circuitry

SLEW RATE CONTROL

Voltage tracking is achieved by controlling the slew rate of a
rising or falling supply by an external capacitor on the SLEW
pin. Alternatively, this pin can be overdriven with a supply
which will result in the output following this supply. The gate
responds to maintain ~100mV between the VOUTFB pin and
the SLEW pin

ADM1202 POWER FAIL DETECTOR

Figure 4 shows the internal circuitry that enables the Power Fail
Detector on the ADM1202. An internal comparator with a

0.6V reference is used for detection. An external resistor
divider can be used to divide down a voltage rail to trigger a
power fail fault at the appropriate level. The Power Fail Output,
PFO, will assert high when a power fail condition occurs. Note
that there is no internal shutdown action from a Power Fail
event. A 10K is recommended on the PFO pin in order to
ensure it is either pulled up or down during powerup. The pin
will be in high impedance while Vcc < UVLO and may result in
invalid power fail signals.

Figure 6. Tracking up Waveforms

Rev. PrF | Page 4 of 6

Preliminary Technical Data ADM1202

PIN CONFIGURATIONS

UP / DOWN

1

ADM1202-1AUJ

2

TOP VIEW

(Not to Scale)

PFO

V

OUTFB

3

4

8

7

6

5

V

CC

PFIGND

GATE

C

SLEW

UP / STOP

PFO

V

OUTFB

1

ADM1202-2AUJ

2

TOP VIEW

(Not to Scale)

3

4

PIN FUNCTIONAL DESCRIPTIONS

Pin No. Name Description

1 UP/DOWNb or UP/STOPb

2 GND Chip Ground Pin.
3 PFO Logic Output. Asserts high when a power fail event occurs.
4 VOUTFB Monitors the Source of the external FET
5 CSLEW

6 GATE Drives the GATE node of the external FET
7 PFI

8 VCC Chip Power Supply, 2.7V to 16.5V.

Logic Pin. Drive high to initiate track up off all ADM1202 controlled rails. Drive low to
initiate track down of output (ADM1202-1) or a fast shutdown of output (ADM1202-2).

Connect to an external capacitor to control the slew rate of the output at turn on (and
turn-off for ADM1202-1).

Power Fail Detector Input Pin. A power fail fault is registered at a voltage of 0.6V rising
on this pin. An external resistor divider sets the output voltage that trips a power fail
fault.

8

7

6

5

V

CC

PFIGND

GATE

C

SLEW

Rev. PrF | Page 5 of 6

ADM1202

Preliminary Technical Data

2005

PR05130-0-2/05(PrF)

OUTLINE DIMENSIONS

Figure XX. 8-Lead TSOT Package (UJ-8)—Dimensions shown in millimeters

ESD CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the
human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.

Table 3. Ordering Guide

Part Number Variant Temperature Package Package Description Package Outline

ADM1202-1AUJ UP/DOWNb logic input –40°C to +85°C TSOT UJ-8
ADM1202-2AUJ UP/STOPb logic input –40°C to +85°C TSOT UJ-8

003 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective companies.
Printed in the U.S.A.

Rev. PrF | Page 6 of 6