Analog Devices ADM1070 Datasheet

a

–48 V Hot Swap Controller

ADM1070

FEATURES
Allows Safe Board Insertion and Removal from a Live

–48 V Backplane
Typically Operates from –36 V to –80 V
Tolerates Transients up to –200 V (Limited by External

Components)
Accurate Programmable Linear Current Limit for

In-Rush Control and Short Circuit Protection
Programmable Timeout in Current Limit
Limited Consecutive Retry:

Auto-Restart after Current Limit Timeout

Shutdown after Seven Consecutive Auto Restarts

Provides Immunity from Step Induced Current Spikes
Default Timing Provided with no TIMER Capacitor
Single Pin Undervoltage/Overvoltage Detection
Programmable Operating Voltage Window
Programmable Undervoltage/Overvoltage Time Filter
Small 6-Lead SOT-23 Package

APPLICATIONS
Central Office Switching
–48 V Distributed Power Systems
Negative Power Supply Control
Hot Board Insertion
Electronic Circuit Breaker
High Availability Servers
Programmable Current Limiting Circuit
–48 V Power Supply Modules

0V

V

DD

R1

R2

–48V

V

EE

FUNCTIONAL BLOCK DIAGRAM

16k⍀

R

DROP

V

IN

VCC AND
REFERENCE
GENERATOR

100mV

ADM1070

UV/OV

TIMER

()*

12V

OVER-UNDER

VOLTAGE DETECTION

CIRCUIT

FAULT TIMER AND

CONTROL

OSCILLATOR

*OPTIONAL TIMER CAPACITOR

EN

C

V

CC

V

REF

V

IN

45␮A

GATE

SENSE

V

EE

LOAD

Q1

R

SENSE

V

OUT

GENERAL DESCRIPTION

The ADM1070 is a negative voltage hot swap controller that
allows a board to be safely inserted and removed from a live
–48 V backplane. The part achieves this by providing robust
current limiting, protection against transient and nontransient
short circuits and overvoltage and undervoltage conditions. The
ADM1070 typically operates from a negative voltage of up to
–80 V and can tolerate transient voltages of up to –200 V.

In-rush current is limited to a programmable value by control­ling the gate drive of an external N-channel FET. The current
limit can be controlled by the choice of the sense resistor,
R

. Added control of the in-rush current is provided by an

SENSE

on-chip timer that uses pulsewidth modulation to allow the
maximum current to flow for only 3% of the time. An autorestart
occurs after a current limit timeout. After seven successive
autorestarts, the fault will be latched and the part goes into
shutdown with the result that the external FET is disabled until
the power is reset.

REV. 0

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. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.

The ADM1070 also features single-pin undervoltage and over­voltage detection. The FET is turned off if a nontransient
voltage less than the undervoltage threshold, typically –36 V, or
greater than the overvoltage threshold, typically –77 V, is detected
on the UV/OV Pin. The operating voltage window of the
ADM1070 is programmable and is determined by the ratio R1/R2.

Time filtering on the undervoltage and overvoltage detection
and current limiting is programmable via the TIMER Pin. An
external capacitor connected between the TIMER Pin and V

EE

determines the undervoltage/overvoltage time filter and the
timeout in current limit. If the pin is tied to V

, the time filter

EE

values and the current limit timeout revert to default figures.

The ADM1070 is fabricated using BiCMOS technology for mini­mal power consumption. The part is available in a small
6-Lead SOT-23 package.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]www.analog.com
Fax: [phone] © Analog Devices, Inc., 2002

ADM1070–SPECIFICATIONS

(VDD = 0 V, VEE = –48 V, R
wise noted.)

= 16 k⍀, TA = –40ⴗC to +85ⴗC, unless other-

DROP

Parameter Min Typ Max Unit Test Conditions

BOARD SUPPLY
(not connected directly to device)

Maximum Voltage Range –200 –48 –20 V Limited by Voltage Capability of

External Components*

Typical Operating Voltage Range –77 –48 –36 V R

= 16 kΩ, R1/R2 = 40*

DROP

VIN PIN––SHUNT REGULATOR

Operating Supply Voltage Range, V
Quiescent Supply Current, I
Maximum Shunt Supply Voltage, V
Undervoltage Lockout, V

LKO

SS

SS

SS

11.5 12.3 13 V ISS = 1.5 mA to 4.25 mA

0.4 0.85 1.3 mA VSS = 11.5 V

12.5 14 V ISS = 20 mA

7 8.5 10.5 V

UV/OV PIN––UNDERVOLTAGE AND
OVERVOLTAGE DETECTION

Undervoltage Falling Threshold, V
Undervoltage Rising Threshold, V
Undervoltage Hysteresis, V

UVH

Overvoltage Falling Threshold, V
Overvoltage Rising Threshold, V
Overvoltage Hysteresis V
Power-On Reset Delay, t

Voltage Fault Filter Time (UV/OV Out of

Voltage

Input Current, I

Window), t

VMON

OVH

POR

FLT

UVF

UVR

OVF

OVR

0.81 0.86 0.91 V

0.86 0.91 0.96 V
45 mV

1.85 1.93 2.01 V

1.89 1.97 2.05 V
–45 mV

1.10 1.70 2.30 ms TIMER Pin Tied to V

(V

< UV/OV < V

0.90 1.21 1.51 ms C

UVR

= 470 pF

TIMER

(V

< UV/OV < V

UVR

OVF

OVF

1.10 1.70 2.30 ms TIMER Pin Tied to V

(V

< UV/OV < V

0.90 1.21 1.51 ms C

UVR

= 470 pF

TIMER

< UV/OV < V

(V

UVR

OVF

OVF

1.0 µA

EE

)

)

EE

)

)*

GATE PIN––FET DRIVER

Maximum Gate Voltage, V
Minimum Gate Voltage, V
Pull-Up Current, I

GUP

Pull-Down Current, I
Hold-off Impedance, R

GMAX

GMIN

GDP

GOFF

11 12 13 V I
050mVI
–20 –40 –55 µAV
10 30 mA V

10 k⍀ V
30 k⍀ V

= –1 µA

GATE

= 1 µA

GATE

= 0 V to 9 V, V

GATE

= V

GATE

GATE

GATE

SS

< 2 V, VSS > 11 V
< 2 V, VSS > 2 V

SENSE

= 0

SENSE PIN––CURRENT SENSE

Analog Current Limit Voltage (Rising),V

LIM

90 100 110 mV I

= 0 µA to –15 µA

GATE

Circuit Breaker Limit Voltage (Rising) 75 88 100 mV
Circuit Breaker Limit Voltage (Rising) –12 mV
(With Respect to V

LIM

), V

LIMITON

Circuit Breaker Limit Voltage (Falling) 60 79 95 mV
Circuit Breaker Limit Voltage (Falling) –21 mV
(With Respect to V

LIM

), V

LIMITOFF

Fast Current Limit Voltage 107 126 145 mV
Fast Current Limit Voltage 26 mV
(With Respect to V
Control Loop Transconductance, 1.5 2.75 4 µA/mV I

/dV

(dI

GATE

SENSE

Maximum Current Limit On Time, t

Current Limit PWM Off Time 320 450 580 ms TIMER Pin Tied to V

)

LIM

< ⫾30 µA, TA = 25°C

GATE

)

LIMITON

10 14 18 ms TIMER Pin Tied to V

(V

< UV/OV < V

7.4 9.9 12.4 ms C

240 320 400 ms C

UVR

= 470 pF

TIMER

(V

< UV/OV < V

UVR

(V

< UV/OV < V

UVR

= 470 pF

TIMER

(V

< UV/OV < V

UVR

OVF

OVF

OVF

OVF

EE

)

)*

EE

)*

)*

Current Limit PWM Duty Cycle 3 % (Typical Only)
Number of Consecutive PWM Retry Cycles 7 (Typical Only)

REV. 0–2–

Parameter Min Typ Max Unit Test Conditions

WARNING!

ESD SENSITIVE DEVICE

SENSE PIN––CURRENT SENSE (continued)

Continuous Short Circuit Time before Latched 2100 2800 3500 ms TIMER Pin Tied to V

Shutdown, t

SHORT

Operating Sense Voltage Range, V
Input Current, I

TIMER PIN

SENSE

––

TIMING CONTROL

SOP

1500 2000 2500 ms C

0 0.11 V
–500 +500 µAV

(V

< UV/OV < V

UVR

= 470 pF

TIMER

(V

< UV/OV < V

UVR

= –2 V to +2 V

SENSE

Internal Oscillator Default Frequency, 9.0 kHz TIMER Pin Tied to V

f

TIMERINT

External/Internal Selection Threshold, V
High Trip Threshold, V
Low Trip Threshold, V
Pull-Down Current, I
Pull-Up Current, I
Start-Up Current, I

*Not production tested. Guaranteed by design.

Specifications subject to change without notice.

(Not Seen at Pin)

TIMERTHH

TIMERTHL

TIMERDN

TIMERUP

TIMERSTART

TIMERTHEI

0.3 0.45 0.6 V

3.0 3.5 4.0 V

1.2 1.5 1.8 V
15 24 31 µAV
–15 –24 –31 µAV
–12 –19 –26 µAV

TIMER

TIMERTHEI

< V

TIMER

> V

TIMERTHH

< V

TIMERTHEI

TIMER

ADM1070

EE

)

OVF

)*

OVF

EE

< V

TIMERTHL

ABSOLUTE MAXIMUM RATINGS*

(All voltages referred to VEE, unless otherwise noted. TA = 25°C, unless other-

wise noted.)

Supply Voltage (VDD–VEE) . . . . . . . . . . . . . –0.3 V to –200.0 V

Maximum Shunt Supply Voltage, V

. . . . . . . . . . . . . . . 16 V

SS

SENSE Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . –2 V to +16 V

GATE Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +16 V

UV/OV Pin . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +15 V

TIMER Pin . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +10 V

Maximum Junction Temperature . . . . . . . . . . . . . . . . . 125°C

Temperature Range . . . . . . . . . . . . . . . . . . . . –40°C to +85°C

Continuous Power Dissipation . . . . . . . . . . . . . . . . . 282 mW

Storage Temperature Range . . . . . . . . . . . –65°C to +150°C

Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . . 300°C

*This is a stress rating only and functional operation of the device at these or any

other conditions above those indicated in the operation sections of this specifica­tion is not implied. Exposure to absolute maximum rating conditions for extended
periods of time may affect reliability.

ORDERING GUIDE

Temperature Package Package

Model Range Description Option

ADM1070ART –40ºC to +85ºC 6-Lead RT-6

THERMAL CHARACTERISTICS

6-Lead SOT-23 Package:

␪

= 226.6°C/W, ␪JC = 91.99°C/W

JA

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 the
ADM1070 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.

REV. 0

–3–

ADM1070

PIN CONFIGURATION

SENSE

V

EE

V

1

ADM1070ART

2

3

IN

TOP VIEW

(Not to Scale)

6

5

4

GATE

UV/OV

TIMER

PIN FUNCTION DESCRIPTION

Pin No. Mnemonic Function

1 SENSE Connection to External FET Source Voltage. A sense resistor is connected in the supply path

between the SENSE Pin and V

, and the voltage across this resistor is monitored to detect current

EE

faults. This voltage is fed as an input to the linear current regulator. When it reaches 100 mV for
a specified period, t

, the regulator reduces the gate voltage and drives the FET as a linear pass

ON

device. If current monitoring is not required, this feature can be turned off by shorting the
SENSE Pin and VEE together.

2V

EE

Device Negative Supply Voltage. This pin should be connected to the lower potential of the
power supply.

3V

IN

Shunt Regulated On-Chip Supply, Nominally V

EE

+ 12.3 V. This pin should be current fed

through a dropper resistor that is connected to the higher potential of the power supply inputs.

4TIMER

Allows User Control over Timing Functions by Determining Frequency of Oscillator. Fre­quency set by connecting external capacitor to VEE. Tying pin directly to VEE causes oscillator to
default to internally set value.

5 UV/OV Input Pin for Overvoltage and Undervoltage Detection Circuitry. The voltage appearing on the

UV/OV Pin is proportional to board supply and is determined by external resistors. When the
voltage on UV/OV falls below the undervoltage threshold of 0.86 V, the GATE Pin is driven low.
When the voltage appearing at the UV/OV Pin rises above the overvoltage threshold of 1.97 V,
the GATE Pin is also driven low. If the external resistor ratio of R1/R2 = 40 is used, then this
gives an operating range of –36 V to –77 V.

6 GATE Output to External FET Gate Drive. Controlled by linear current regulator. The gate is driven

low if an overvoltage or undervoltage fault occurs or if a current fault lasts for longer than the
time, t

. When in linear regulation, the GATE Pin voltage is controlled as part of the servo loop.

ON

No external compensation is required. When the FET is fully enhanced and the load capacitance
has been charged, the GATE Pin reaches a high level of typically 12 V.

REV. 0–4–

2.0

TEMPERATURE – ⴗC

–45

V

Z

– V

14.5

14.0

13.5

13.0

12.5

12.0

11.5

11.0
–35 –25 –15 –5 5 15 25 35 45 55 65 75 85

1.8

1.6

1.4

1.2

1.0

– mA

IN

I

0.8

0.6

0.4

0.2

0
–50 –35

Typical Performance Characteristics–

–20 –5 10 25 40 55 70

TEMPERATURE – ⴗC

ADM1070

85

1000

100

– mA

IN

I

10

1

0.1

10

9

8

TPC 1. IIN vs. Temperature

+85ⴗC

+25ⴗC

02

4681012 14

VIN – V

TPC 2. IIN vs. V

TPC 4. VZ vs. Temperature

12

11

10

– V

9

LKO

V

8

–40ⴗC

16

IN

7

6

–50

–35 –20 –5 10 25 40 55 70 85

TEMPERATURE – ⴗC

TPC 5. Undervoltage Lockout, V

100

95

90

vs. Temperature

LKO

RISING

7

– V

6

Z

R

5

4

REV. 0

3

2

–45

–35 –25 –15 –5 5 15 25 35 45 55 65 75 85

TPC 3. RZ vs. Temperature

TEMPERATURE – ⴗC

–5–

85

– mV

80

CB

V

75

70

65

60

–35 –20 –5 10 25 40 55 70 85

–50

TEMPERATURE – ⴗC

FALLING

TPC 6. Circuit Breaker Current Limit Voltage,

vs. Temperature

V

CB