Datasheet ADM6819 Datasheet (ANALOG DEVICES)

V

V

FET Drive Simple Sequencers

®

FEATURES

Single chip enables power supply sequencing of two

supplies
On-board charge pump fully enhances N-channel FET
Adjustable primary supply monitor to 0.618 V
Delay from primary supply to secondary supply enabled

Fixed 300 ms delay (ADM6819)

Capacitor adjustable delay (ADM6820)
Logic/analog driven enable input (ADM6819)

−40°C to +85°C operating range
Packaged in small 6-lead SOT-23 package
Pin-to-pin compatibility with MAX6819/MAX6820

APPLICATIONS

Multivoltage systems
Dual voltage microprocessors/FPGAs/ASICs/DSPs
Network processors
Telecom and datacom systems
PC/server applications

ADM6819/ADM6820

FUNCTIONAL BLOCK DIAGRAM

CC1

V

CC2

R1

SETV

R2

V

CC1

UVLO

0.618V

ADM6819/

ADM6820

GND

V

CC2

CHARGE

PUMP

LOGIC

0.618V

EN (ADM6819) - DIGITAL/ANALOG

SETD (ADM6820)

Figure 1.

V

DRIVER

TIMER

FET

FET

Q1

GATE

CC1

V

OUT

CC2

5133-001

GENERAL DESCRIPTION

The ADM6819 and ADM6820 are simple power supply sequencers
with FET drive capability for enhancing N-channel MOSFETs.
These devices can monitor a primary supply voltage and
enable/disable an external N-channel FET for a secondary
supply. The ADM6819 has the ability to monitor two supplies.
When more than two voltages require sequencing, multiple
ADM6819/ADM6820 devices can be cascaded to achieve this.
The devices operate over a supply range of 2.95 V to 5.5 V.

An internal comparator monitors the primary supply using the
VSET pin. The input to this comparator is externally set via a
resistor divider from the primary supply. When the voltage at
the VSET pin rises above the comparator threshold, an internal
charge pump on the GATE output enhances the secondary
supply FET.

The ADM6819 features an enable (EN) pin that is fed to the
input of an additional comparator and reference circuit. This
pin can be used as a digital enable or a secondary power good
comparator to monitor a second supply and enables the GATE
only if both supplies are valid. When both inputs of the internal
comparators are above the threshold, a fixed 300 ms timeout
occurs before the GATE is driven high and the secondary
supply is enabled.

The ADM6820 has only one comparator that is on the SETV
pin. It also features a timeout period that is adjustable via a
single external capacitor on the SETD pin.

The ADM6819/ADM6820 are packaged in small 6-lead SOT-23
packages.

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
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 owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2006 Analog Devices, Inc. All rights reserved.

ADM6819/ADM6820

TABLE OF CONTENTS

Features.............................................................................................. 1

Pin Configuration and Function Descriptions..............................7

Applications....................................................................................... 1

Functional Block Diagram .............................................................. 1

General Description ......................................................................... 1

Revision History ............................................................................... 2

Specifications..................................................................................... 3

Timing Diagrams.............................................................................. 4

Absolute Maximum Ratings............................................................ 6

Thermal Characteristics .............................................................. 6

ESD Caution.................................................................................. 6

REVISION HISTORY

7/06—Rev. 0: Initial Version

Typical Performance Characteristics..............................................8

Theory of Operation ...................................................................... 10

SETV Pin ..................................................................................... 10

EN Pin.......................................................................................... 10

GATE Pin .................................................................................... 10

SETD Pin..................................................................................... 10

Outline Dimensions....................................................................... 11

Ordering Guide .......................................................................... 11

Rev. 0 | Page 2 of 12

ADM6819/ADM6820

SPECIFICATIONS

V

or V

CC1

= 2.95 V to 5.5 V, TA = −40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C.

CC2

Table 1.

Parameter Min Typ Max Units Conditions

V

, V

PINS V

CC1

CC2

Operating Voltage Range, V
V

or V

CC1

V

CC1

V

CC1

Supply Current, ICC 350 500 μA V

CC2

or V

Disable Mode Current 250 μA V

or V

CC2

Slew Rate

CC2

2

1.2/t
Undervoltage Lockout, V

UVLO

CC1

or V

0.9 5.5 V V

CC2

6 V/s ADM6819

V/s ADM6820

DELAY

2.4 2.525 2.65 V VCC falling

CC1

CC1

CC1

CC1

or V

CC2

or V

CC2

= V

= 3.3 V

CC2

= V

= 3.3 V, EN = GND

CC2

SETV PIN

SETV Threshold, VTH 0.602 0.618 0.634 V V
SETV Input Current
SETV Threshold Hysteresis
SETV to GATE Delay, t

2

240 300 350 ms V

DELAY

10 100 nA

−1 % V

rising, enables GATE

SETV

falling, disables GATE

SETV

> V

SETV

TH

SETD PIN ADM6820

SETD Ramp Current, I

SETD

300 500 730 nA
400 500 600 nA TA = 25°C
SETD Voltage, V

1.295 1.326 1.357 V

SETD

GATE PIN

GATE Turn-On Time, tON 0.5 1.5 10 ms C
GATE Turn-Off Time, t
GATE Voltage, V

GATE

30 μs C

OFF

4.5 5.5 6.0 V With respect to V

= 1500 pF, V

GATE

= 1500 pF, V

GATE

4.0 5.0 6 V With respect to V

8.9 9.4 9.9 V With respect to V

8.2 8.6 9.1 V With respect to V
ENABLE PIN

EN Input Voltage Low, VIL 0.4 V V
EN Input Voltage High, VIH 2.0 V V

1

100% production tested at TA = +25°C. Specifications over temperature limit are guaranteed by design.

2

Guaranteed by design, not production tested.

3

t

(s) = 2.65 × 106 × C

DELAY

4

Highest supply pin is represented by V

5

Highest supply pin is represented by V

.

SET

= 2.95 V.

CCx

= 5.5 V.

CCx

CC1

CC1

or V
or V

CC2

CC2

1

must be > 2.95 V
must be > 2.95 V

3

; VEN > VTH (ADM6819)

= 3.3 V, V

CC2

= 3.3 V, V

CC2

, R

CCx

, R

CCx

, R

CCx

, R

CCx

GATE

GATE

> 50 MΩ to V

GATE

> 5 MΩ to V

GATE

> 50 MΩ to V

GATE

> 5 MΩ to V

GATE

must be > 2.95 V
must be > 2.95 V

= 7.8 V
= 0.5 V

CCx

CCx

CCx

CCx

4

4

5

5

Rev. 0 | Page 3 of 12

ADM6819/ADM6820

V

V

TIMING DIAGRAMS

V

CC2

CC1

Q1

V

CC1

V

CC2

CC1

V

OUT

CC2

CHARGE

PUMP

UVLO

R1

R3

R4

SETV

R2

0.618V

ADM6819

GND

LOGIC

0.618V

EN

V

FET

FET

DRIVER

GATE

05133-014

Figure 2. ADM6819 Solution for Validating Two Supplies Before Sequencing

V

SETV

V

GATE

Figure 3. ADM6819/ADM6820 Timing Diagram Using SETV for Sequencing

0.618V

t

DELAY

(ADM6819 = 300ms,

ADM6820 = ADJ)

t

ON

90%

10% 10%

V

CC2

+ 5.5V (typ)

t

OFF

05133-015

V

V

SETV

V

GATE

0.618V

EN

0.618V

t

DELAY

(300ms)

t

ON

90%

10% 10%

V

CC2

+ 5.5V (typ)

t

Figure 4. ADM6819 Timing Diagram Using EN and SETV for Sequencing

OFF

5133-016

Rev. 0 | Page 4 of 12

ADM6819/ADM6820

V

V

V

V

V

V

IN

= 3.3V

IN

= 3.0V

IN

= 5

Q1

Q2

= 5

OUT

V

= 3.3V

OUT

V

= 3.0V

OUT

V

CC2

V

CC1

R1

SETV

R2

GATE

ADM6819/

ADM6820

EN/SETD

GND

R3

R4

V

CC2

V

CC1

ADM6819/

ADM6820

SETV

GND

GATE

EN/SETD

05133-017

Figure 5. ADM6819/ADM6820 Solution for Sequencing Three Supply Rails

Rev. 0 | Page 5 of 12

ADM6819/ADM6820

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

V

, V

−0.3 V to +6.0 V

CC1

CC2

SETV, SETD, EN −0.3 V to +30 V
GATE −0.3 V to (V
Storage Temperature −65°C to +150°C
Operating Temperature Range −40°C to +85°C
Lead Temperature (Soldering 10 sec) 300°C
Junction Temperature 150°C

+ 11 V)

CCx

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.

Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.

THERMAL CHARACTERISTICS

θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.

Table 3. Thermal Resistance

Package Type θJA Unit

6-Lead SOT-23 169.5 °C/W

Rev. 0 | Page 6 of 12

ADM6819/ADM6820

SETV

SETV

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

V

CC1

GND

1

ADM6819

2

TOP VIEW

(Not to S cale)

3

6

5

4

V

CC2

GATE

EN

05133-002

Figure 6. ADM6819 Pin Configuration

Table 4. Pin Function Descriptions

Pin Number

ADM6819 ADM6820

1 1 V

Mnemonic Description

CC1

Supply Voltage 1. Either V

CC1

FET Drive.
2 2 GND Chip Ground Pin.
3 3 SETV

Sequenced Threshold Set. Connect to an external resistor divider to set the V

threshold that enables GATE turn-on. The internal reference is 0.618 V.
4 – EN

Active-High Enable. GATE drive is enabled t

immediately disabled when EN is driven low. Connect this pin to the higher of V

if not used. EN is internally identical to SETV (0.618 V threshold) and, therefore, can

V

CC2

be used as a second supply monitor, enabling two supplies to be validated before

sequencing begins.
– 4 SETD

5 5 GATE

GATE Delay Set Input. Connect an external capacitor from SETD to GND to adjust the

delay from SETV > V

to GATE turn-on. t

TH

GATE Drive Output. GATE drives an external N-channel FET to connect V

GATE drive enables t

after SETV exceeds V

DELAY

immediately disabled when SETV drops below V

enabled, an internal charge pump drives GATE above V

N-channel FET.
6 6 V

CC2

Supply Voltage 2. Either V

CC1

external FET Drive.

V

CC1

GND

1

ADM6820

2

TOP VIEW

(Not to S cale)

3

6

5

4

V

CC2

GATE

SETD

05133-003

Figure 7. ADM6820 Pin Configuration

or V

must be greater than the UVLO to enable external

CC2

after EN is driven high. GATE drive is

DELAY

(s) = 2.652 × 106 × C

DELAY

and ENABLE is driven high. GATE drive is

TH

or ENABLE is driven low. When

TH

or V

must be greater than the UVLO to enable the

CC2

to fully enhance the external

CCX

SET

(F).

to the load.

CC2

CC1

or

CC1

Rev. 0 | Page 7 of 12

ADM6819/ADM6820

TYPICAL PERFORMANCE CHARACTERISTICS

0.50

0.65

0.45
I

(V

= 3.3V, V

CC2

0.40

0.35

0.30

0.25

SUPPLY CURRENT (mA)

0.20

0.15

0.10

–25 0 25 50 75 100 125

–50

CC1

I

(V

= 5V, V

CC1

CC1

TEMPERATURE (° C)

CC2

CC2

= 3.3V)

= 5V)

VEN = 2V
V

= 2V

SETV

150

05133-004

Figure 8. Supply Current vs. Temperature

0.50

V

= 0V

CC1

0.45

V

= 2V

EN

V

= 2V

SETV

0.40

0.35

0.30

(mA)

0.25

CC2

I

0.20

0.15

0.10

0.05

0

0.50

0.45

0.40

0.35

0.30

(mA)

0.25

CC2

I

0.20

0.15

0.10

0.05

0

123456

0

V

(V)

CC2

Figure 9. I

V

= 3.3V

CC1

V

= 2V

EN

V

= 2V

SETV

123456

0

Figure 10. I

vs. V

CC2

(V)

vs. V

CC2

CC2

CC2

V

CC2

7

05133-005

7

05133-006

0.64

0.63

0.62

0.61

0.60

SUPPLY CURRENT (mA)

0.59

0.58
–50 150

–25 0 25 50 75 100 125

TEMPERATURE (°C)

05133-007

Figure 11. Supply Current vs. Temperature

14

12

10

(V)

8

GATE

V

6

4

V

2

0

06

14

12

10

(V)

8

GATE

V

6

4

2

0

06

12345

V

(V)

CC2

Figure 12. V

12345

Figure 13. V

vs. V

(V)

vs. V

CC2

CC2

GATE

V

CC2

GATE

V
V

CC1
EN
SETV

V
V
V

= 3.3V

= 2V

= V

CC1

= 2V

EN
SETV

= 0V

= 1V

CC2

05133-008

05133-009

Rev. 0 | Page 8 of 12

ADM6819/ADM6820

5

5

14

12

10

(V)

8

GATE

V

6

4

V

2

0

06

12345

V

(V)

CC2

Figure 14. V

340

330

320

310

300

(ms)

290

DELAY

280

t

270

260

250

240

–25 0 25 50 75 100 125

–50 150

TEMPERATURE (°C)

Figure 15. t

vs. V

GATE

vs. Temperature

DELAY

CC2

V
V

CC1
EN
SETV

= 3.3V

= 2V

= 1V

05133-010

05133-011

V

V

V/DIV

V

GATE

V/DIV

SETV

GATE

20µs/DIV

Figure 16. Gate Turn-Off Time

1ms/DIV

Figure 17. Gate Turn-On Time

C

C

LOAD

LOAD

= 1500pF

= 1500pF

5133-018

5133-019

Rev. 0 | Page 9 of 12

ADM6819/ADM6820

V

V

V

V

V

V

V

V

THEORY OF OPERATION

The ADM6819/ADM6820 provide local voltage sequencing in
multisupply systems.
application diagrams for these devices.

= 3.3

IN

VIN = 3.0V V

R1

R2

= 3.3

IN

VIN = 3.0V V

R1

R2

Figure 18 and Figure 19 show typical

Q1

V

CC2

V

CC1

SETV

Figure 18. ADM6819 Applications Diagram

V

CC2

V

CC1

SETV

Figure 19. ADM6820 Applications Diagram

GATE

ADM6819

GND

GATE

ADM6820

GND

EN

SETD

Q1

ON

C

SET

OFF

OUT

OUT

OUT

OUT

= 3.3
= 3.0V

= 3.3
= 3.0V

SETV PIN

The ADM6819/ADM6820 enable a supply after a monitored
supply voltage exceeds a programmed threshold. This threshold
is programmed by a R1/R2 resistor divider on the SETV pin.
Once the voltage on SETV exceeds the 0.618 V threshold, the
FET switches on after the delay timer expires. On the
ADM6820, this delay is programmable using a capacitor on the
SETD pin. On the ADM6819, this delay is fixed at 300 ms and
the EN pin must be valid high to begin the timer. The required
turn-on voltage is calculated by the following equation:

R1 = R2 ((VTRIP/V

TH

) – 1)

where:

05133-012

VTRIP is the minimum turn-on voltage at the supply being
monitored.

V

= 0.618 V.

TH

High value resistors can be used because the SETV input
current is typically 10 nA.

EN PIN

The ADM6819 has an enable (EN) pin connected to the input
of a second comparator, which is identical to that on the VSET
pin. EN can be used as a digital input provided the signal V
below 0.6 V. Alternatively, the enable input can be used to
validate a second supply. The fixed 300 ms timer does not begin

05133-013

counting until both SETV and EN are above the threshold. As a
result, the output is not enabled until this timer has expired.

is

OL

When the primary supply is above the desired threshold, the
ADM6819/ADM6820 are designed to control the N-channel
FET in the secondary power path to enable the secondary
supply. The GATE pin is held low while both V

CC1

and V

CC2

are
below the undervoltage threshold, ensuring that the FET is held
off. When V

CC1

or V

is above UVLO and the primary supply

CC2

is above the desired level dictated by the resistor divider to the
VSET pin, the external FET is driven on after the delay has
expired. An internal charge pump enhances the external FET. A
FET with a low drain-source resistance and low V

should be

TH

chosen to reduce voltage drop across the drain-source when the
FET is fully enhanced. Either supply may act as the primary
source if V
capacitor of typically 100 nF should be used on whichever V

CC1

or V

is greater that 2.95 V. A decoupling

CC2

CC

is the main supply.

GATE PIN

The internal charge pump is capable of driving the gate of an
N-channel MOSFET with no external capacitors. This ensures
that the MOSFET is enhanced to provide a minimum voltage
drop across the MOSFET, thus reducing the voltage drop across
the FET. This charge pump is designed to drive the high imped­ance capacitive load of a MOSFET gate input. The GATE pin
should not be resistively loaded because it reduces the gate drive
capability. During undervoltage lockout, GATE is held to GND.

SETD PIN

The ADM6820 features a capacitor adjustable sequencing delay.
A capacitor connected to the SETD pin determines the length
of the sequencing delay. The sequencing delay can be calculated
by the following equation:

(s) = 2.652 × 106 × CSET

t

DELAY

The ADM6819 has a fixed 300 ms delay.

Rev. 0 | Page 10 of 12

ADM6819/ADM6820

OUTLINE DIMENSIONS

2.90 BSC

45

2.80 BSC

2

0.95 BSC

1.90
BSC

1.45 MAX

0.50

0.30

Dimensions shown in millimeters

SEATING
PLANE

(RJ-6)

0.22

0.08
10°

4°
0°

0.60

0.45

0.30

1.60 BSC

PIN 1

INDICATOR

1.30

1.15

0.90

0.15 MAX

6

1 3

COMPLIANT TO JEDEC STANDARDS MO-178-AB

Figure 20. 6-Lead Small Outline Transistor Package [SOT-23]

ORDERING GUIDE

Model Temperature Range Package Description Package Option Branding

ADM6819ARJZ-REEL7

ADM6820ARJZ-REEL7

1

Z = Pb-free part.

1

−40°C to +85°C

1

−40°C to +85°C

6-Lead Small Outline Transistor Package [SOT-23] RJ-6 M2R

6-Lead Small Outline Transistor Package [SOT-23] RJ-6 M2S

Rev. 0 | Page 11 of 12

ADM6819/ADM6820

NOTES

©2006 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D05113-0-7/06(0)

Rev. 0 | Page 12 of 12