ANALOG DEVICES ADM1200 Service Manual

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FET Driver with Programmable Slew Rate

Preliminary Technical Data

FEATURES

Enables Power Supply Tracking of multiple supplies
Capacitor Adjustable Linear Slew Rate
On Board Charge Pump Fully enhances NFET
Up/Down slew rate control to approx. +/-100mV
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 Datacoms Systems
Multi voltage Network Processors , FPGAs, ASICs, DSPs
PC/Server Applications

GENERAL DESCRIPTION

The ADM1200 is FET driver capable of driving N channel
FETs. Is features a capacitor programmable SLEW rate control
system ensuring that the output voltage rises and falls at a
controlled rate and in a linear fashion. The ADM1200 is
designed to ensure that the output voltage follows the voltage on
the SLEW pin to within ~100mV. It can also be cascaded to
perform simple tracking functionality of supply rails ensuring
that each 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
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 slew 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 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.

pin and can be programmed from 100V/s to

SLEW

SLEW

pin of

OUTFB

)

V

IN

3.3VIN

UP/DOWN

2.5VIN

1.5VIN

Functional Block Diagram

2.7V - 16.5V

V

CC

V

UP/DOWN

(ADM1200-1)

UP/STOP

(ADM1200-2)

C

SLEW

CHARGE

UP / DOWN
DETECTOR

C

SLEW

SLEW RATE

CONTROL

LOGIC

GND

PUMP

FET

DRIVER

ADM1200

FET

Applications Diagram

Q

GATE

V

OUT

GATE

V

OUT

GATE

V

OUT

20nF

20nF

20nF

1

Q

2

Q

3

C

SLEW

V

cc

V

cc

UP/DOWN

C

SLEW

V

cc

V

cc

UP/DOWN

C

SLEW

V

cc

V

cc

UP/DOWN

C

SLEW

ADM1200-1

GND

ADM1200-1

GND

ADM1200-1

GND

ADM1200

Q

GATE

V

OUT

3.3VOUT

2.5VOUT

1.5VOUT

1

3.3V

2.5V

1.5V

V

OUT

Rev. PrJ

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 Anal og Devices. Trademarks and
registered trademarks are the property of their respective companies.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]
Fax: [phone] © 2005 Analog Devices, Inc. All rights reserved.

www.analog.com

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 0.5 1.5

Up/Downb Pin
Input Threshold 0.6 0.63 0.66
Input Threshold Hysteresis 60 mV
Input Current

C

Pin

SLEW

Slew up Current
Slew down Current
Slew Gain 1 V/V V
Minimum Tracking Voltage 0.1 V
Maximum Tracking voltage Vcc – 0.3 V
Tracking Delta 100 mV V
Slew Rate

V

Pin

OUTFB

Input Current
Voltage Range 0 Vcc V Must not exceed VCC

GATE Pin

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

= Full Operating Range, TA = -40°C to +105°C, unless otherwise noted.

CC

2.4 2.525 2.65 V Vcc Rising

UVLO

4 5.5 8 V V

GATE

-100 100 nA

-10
10

100 1000 V/s

-12 12

V

mA

V

µA
µA

µA

µA
µA

mA

Rising

- V

SLEW

SLEW/VOUTFB

OUTFB

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

– VCC; VCC = 2.7V

GATE

– VCC; VCC = 3.3V

GATE

– VCC; VCC = 5.0V

GATE

– VCC; VCC = 16.5V

GATE

Absolute Maximum Ratings

Table 2. ADM1200 Absolute Maximum Ratings

Parameter
VCC Pin -0.3V to 20V
UP/DOWNb, UP/STOPb -0.3V to 20V
C

Pin -0.3V to 20V

SLEW

Gate Pin -0.3V to (VCC + 11V)
V

Pin -0.3V to (VCC + 0.3V)

OUTFB

Power Dissipation TBD
Storage Temperature –65°C to +125°C
Operating Temperature Range –40°C to +105°C
Lead Temperature Range

(Soldering 10 sec)
Junction Temperature 150°C

Rating

300°C

Rev. PrJ | Page 2 of 6

Preliminary Technical Data ADM1200

GENERAL INFORMATION

The ADM1200 provides a solution for slew rate control, linear
supply regulation and voltage tracking. The device 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 providing it does
not exceed the voltage to be expected on the devices V

OUTFB

pin.

GATE

An internal charge pump ensures that the ADM1200 is capable
of fully enhancing an external N channel FET via the GATE
pin. An external capacitor may be required on the GATE node
for stability. During under voltage lockout the GATE pin is held
low to avoid any glitches on the FETs gate and prevent false
power ups.

SLEW

The value of the slew rate capacitor, C
rate of the output voltage. An internal current source charges

in a linear fashion and the GATE voltage is controlled so

C

SLEW

that V

will be regulated to within 100mV from V

OUT

maximum voltage that the ADM1200 can control is 0.3V below
Vcc. Once the SLEW pin reaches this maximum voltage the
GATE is driven fully high.

The C

capacitor is determined by:

SLEW

, will dictate the slew

SLEW

SLEW

. The

UP/DOWN

3.3 V

2.5V

1.5 V

OUTPUT

VOLTAGES

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

UP/STOP

3.3 V

2.5V

1.5 V

OUTPUT

VOLTAGES

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

ENABLING A SINGLE SUPPLY

A single ADM1200 device may be used where a single supply
rail is required to switch on at a controlled linear slew rate (see
Figure 3). The capacitor C

3.3VIN

determines the slew rate

SLEW

Q

1

3.3VOUT

= 10µA / Slewrate(V/s)

C

SLEW

On the ADM1200-2 only, a high to low on the UP/DOWN pin
will enable a current sink on the SLEW pin to discharge the
capacitor at the same rate. This will initiate a SLEW down of the
output.

VOUTFB

The V
within approximately 100mV of the voltage on the SLEW pin.
This pin must not exceed the Vcc voltage at any time or it may
cause damage to the device.

pin monitors the output voltage to ensure it is kept

OUTFB

UP/DOWN AND UP/STOP

Power up can be externally initiated by driving the
UP/DOWNb (ADM1200-1) or UP/STOPb (ADM1200–2) logic
pin high. A low on the ADM1200-1 will initiate a track down
and one the ADM1200-2 the gate will shutdown immediately.
This is illustrated in Figure 1 and Figure 2.

ADM1200-1

V

POWER ON/OFF

C

SLEW

cc

UP/STOP

C

SLEW

GND

GATE

V

OUTFB

1nF

Figure 3. ADM1200 Switching on a Single Supply

MULTI-SUPPLY TRACKING

The ADM1200 can be used to provide a voltage tracking
solution for multiple supply rails. The implementation in Figure
4 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.

In Figure 4, the ADM1200 is configured to control the ramp of
the largest supply first. The output of the first device is

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