Datasheet ADM1200 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 (ADM1200-1)
Emergency Shutdown Feature (ADM1200-2)
Packaged in tiny 6-Lead SOT-23 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 ADM1200 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 ADM1200 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 ADM1200 is offered in two variants. The ADM1200-1
features an UP/DOWNb pin and the ADM1200-2 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 ADM1200-1 will initiate a tracking
down of the supply rails, while a low on the UP/STOPb pin of
the ADM1200-2 will initiate an emergency fast shutdown of all
supply rails simultaneously.

The ADM1200 is packaged in a tiny 6-pin SOT-23 package.

TM

device which

pin of

SLEW

OUTFB

)

Simple Tracker

Functional Block Diagram

V

IN

2.7V - 16.5V

V

CC

V

CHARGE

UP/DOWN

(ADM1200-1)

UP/STOP

(ADM1200-2)

C

SLEW

C

SLEW

UP / DOWN
DETECTOR

SLEW RATE

CONTROL

LOGIC

GND

Applications Diagram

3.3VIN

UP/DOWN

2.5VIN

1.5VIN

V

cc

ADM1200

V

cc

UP/DOWN

C

SLEW

V

cc

V

cc

UP/DOWN

C

SLEW

V

cc

V

cc

UP/DOWN

C

SLEW

GND

ADM1200

GND

ADM1200

GND

C

SLEW

PUMP

FET

DRIVER

ADM1200

GATE

V

OUT

GATE

V

OUT

GATE

V

OUT

FET

20nF

20nF

20nF

ADM1200

Q

1

GATE

V

OUT

Q

1

3.3VOUT

Q

2

2.5VOUT

Q

3

1.5VOUT

V

TM

OUT

Rev. PrH

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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
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registered trademarks are the property of their respective companies.

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Tel: [phone]
Fax: [phone] © 2003 Analog Devices, Inc. All rights reserved.

www.analog.com

Preliminary Technical Data

ADM1200—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

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

-10
10

100 1000 V/s

-10 10

V

mA

V

µA
µA

µA

µA
µA

mA

Rising

SLEW/VOUTFB

Vslew – Vout > 100mV
Vout – Vslew > 100mV
ADM1200-2 only –vgate = 3.0V

– VCC; VCC = 2.7V

GATE

– VCC; VCC = 5.0V

GATE

– VCC; VCC = 16.5V

GATE

Absolute Maximum Ratings

Table 2. ADM1200 Absolute Maximum Ratings

Parameter
VCC Pin 20V
UP/DOWNb, UP/STOPb 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)
Junction Temperature 150°C

Rating

300°C

Rev. PrH | Page 2 of 6

Preliminary Technical Data ADM1200

ENABLING A SINGLE SUPPLY

The ADM1200 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 ADM1200 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 (ADM1200-1) or UP/STOPb (ADM1200–2)
logic pin high. A low on this pin will initiate a power down.

The V

pin monitors the output voltage.

OUTFB

3.3VIN

UP/DOWN

2.5VIN

V

cc

ADM1200

V

cc

UP/DOWN

C

SLEW

V

cc

V

cc

UP/DOWN

C

SLEW

GND

ADM1200

GND

C

SLEW

GATE

V

GATE

V

Q

1

3.3VOUT

20nF

OUT

Q

2

2.5VOUT

20nF

OUT

A single ADM1200 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

, will dictate the

SLEW

slew rate of the GATE voltage at startup. An internal current

10µA source charges C

and the GATE voltage is ramped at

SLEW

the same rate.

Q

3.3VIN

1

3.3VOUT

ADM1200-1

V

POWER ON/OFF

C

SLEW

cc

UP/STOP

C

SLEW

GND

GATE

V

OUTFB

1nF

Figure 1. ADM1200 Switching on a Single Supply

MULTI-SUPPLY TRACKING

The primary function of the ADM1200 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 ADM1200 device driving a FET.

The UP/DOWNb (ADM1200-1) or UP/STOPb (ADM1200-2)
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.

Q

GATE

V

3

1.5VOUT

20nF

OUT

1.5VIN

V

cc

V

cc

UP/DOWN

C

SLEW

ADM1200

GND

Figure 2. ADM1200 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 ADM1200 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 ADM1200-1 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 ADM1200-2 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.

In figure 2, the ADM1200 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.

Rev. PrH | Page 3 of 6

ADM1200 Preliminary Technical Data

UP/DOW N

SLEW RATE CONTROL

3.3V

2.5V

1.5V

OUTPUT

VOLTAGES

Figure 3. ADM1200-1 Power-Up and Power-Down Waveforms

UP/STOP

3.3V

2.5V

1.5V

OUTPUT

VOLTAGES

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.

Figure 6. Tracking up Waveforms

Figure 4. ADM1200-2 Power-Up and Power-Down Waveforms

Rev. PrH| Page 4 of 6

Preliminary Technical Data ADM1200

PIN CONFIGURATIONS

UP / DOWN

1

V

6

CC

UP / STOP

1

ADM1200-1ARJ

GND

V

OUTFB

2

TOP VIEW

(Not to Scale)

3

GATE

5

C

4

SLEW

GND

V

OUTFB

2

3

PIN FUNCTIONAL DESCRIPTIONS

Pin No. Name Description

1 UP/DOWNb or UP/STOPb

2 GND Chip Ground Pin.
3 VOUTFB Monitors the Source of the external FET
4 CSLEW

5 GATE Drives the GATE node of the external FET
6 VCC Chip Power Supply, 2.7V to 16.5V.

Logic Pin. Drive high to initiate track up off all ADM1200 controlled rails. Drive low to
initiate track down of output (ADM1200-1) or a fast shutdown of output (ADM1200-2).

Connect to an external capacitor to control the slew rate of the output at turn on (and
turn-off for ADM1200-1).

ADM1200-2ARJ

TOP VIEW

(Not to Scale)

V

6

CC

GATE

5

C

4

SLEW

Rev. PrH | Page 5 of 6

2005

PR05128-0-2/05(PrH)

ADM1200

Preliminary Technical Data

OUTLINE DIMENSIONS

0.122 (3.10)

0.106 (2.70)

2

BSC

0.020 (0.50)

0.010 (0.25)

4 5 6

0.118 (3.00)

0.098 (2.50)

3

0.037 (0.95) BSC

0.057 (1.45)

0.035 (0.90)

SEATING

PLANE

0.009 (0.23)

0.003 (0.08)

10°

0°

0.022 (0.55)

0.014 (0.35)

0.071 (1.80)

0.059 (1.50)

0.051 (1.30)

0.035 (0.90)

PIN 1

0.059 (0.15)

0.000 (0.00)

1

0.075 (1.90)

Figure 5. 6-Lead SOT-23 Package (RJ-6)—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

ADM1200-1ARJ UP/DOWNb logic input –40°C to +85°C SOT-23 RJ-6
ADM1200-2ARJ UP/STOPb logic input –40°C to +85°C SOT-23 RJ-6

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. PrH | Page 6 of 6