Data Sheet
FEATURES
Controls supply rails from 1.6 V to 16.5 V
Supply voltage range from 2.7 V to 16.5 V
Allows protected board removal and insertion to a live
backplane
External sense resistor provides adjustable analog current
limit with circuit breaker
Soft start controls inrush current profile
Peak fault current limited with fast response
Charge pumped gate drive for external N-FET switch
Automatic retry or latch-off during current fault
Undervoltage lockout
8-lead, TSOT package
1.6 V to 16.5 V Hot Swap Controller
with Soft Start
ADM1170
GENERAL DESCRIPTION
The
ADM1170
is a hot swap controller that safely enables a
printed circuit board to be removed and inserted to a live
backplane. This is achieved using an external N-channel power
MOSFET with a current control loop that monitors the load
current through a sense resistor. An internal charge pump is
used to enhance the gate of the N-channel FET. When an
overcurrent condition is detected, the gate voltage of the FET is
reduced to limit the current flowing through the sense resistor.
The
ADM1170
operates with a supply voltage ranging from
2.7 V to 16.5 V. By using independent SENSE pins from V
CC
,
the
ADM1170
allows for the hot swap of supplies ranging down
to 1.6 V. During an overcurrent condition, the TIMER pin
capacitor determines the amount of time the FET remains at
a current limiting mode of operation until it is shut down. The
ON (ON-CLR) pin is the enable input for the device and can be
used to monitor the input supply voltage. The
ADM1170
also
features soft start to provide the user with a capacitor program-
mable ramping reference to the internal current sense comparator.
This provides a linearly increasing current limit at startup at a
rate set by C
SS
. This helps to reduce and limit large inrush
currents.
This device is available in two options: the
ADM1170-1
with
automatic retry for overcurrent fault and the
ADM1170-2
with
latch-off for an overcurrent fault. Toggling the ON (ON-CLR)
pin resets a latched fault. The
ADM1170
is packaged in an
8-lead TSOT.
APPLICATIONS
Hot swap board insertion: line cards, raid systems
Industrial high-side switches/circuit breakers
Electronic circuit breakers
FUNCTIONAL BLOCK DIAGRAM
V
IN
= 1.8V
LONG
R
SENSE
Q
1
V
OUT
= 1.8V
C
LOAD
SENSE+ SENSE–
V
IN
= 3.3VAUX
LONG
V
CC
R
ON1
GATE
SHORT
ADM1170-1
ON
SS
C
SS
TIMER
C
TIMER
GND
GND
05124-001
R
ON2
GND
LONG
Figure 1.
Rev. A
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ADM1170
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings ............................................................ 4
Thermal Characteristics .............................................................. 4
ESD Caution .................................................................................. 4
Pin Configurations and Function Descriptions ........................... 5
Typical Performance Characteristics ............................................. 6
Theory of Operation ...................................................................... 11
Overview...................................................................................... 11
Data Sheet
UVLO........................................................................................... 11
ON (ON-CLR) Pin ..................................................................... 11
GATE ........................................................................................... 11
Current Limit Function ............................................................. 11
Calculating the Current Limit .................................................. 11
Circuit Breaker Function........................................................... 11
Timer Function ........................................................................... 12
Power-Up Timing Cycle ............................................................ 12
Circuit Breaker Timing Cycle ................................................... 12
Automatic Retry or Latched Off............................................... 13
Soft Start ...................................................................................... 13
Outline Dimensions ....................................................................... 14
Ordering Guide .......................................................................... 14
REVISION HISTORY
1 /13—Rev. 0 to Rev. A
Changes to Figure 36 ...................................................................... 13
Changes to Ordering Guide .......................................................... 14
7/06—Revision 0: Initial Version
Rev. A | Page 2 of 16
Data Sheet
SPECIFICATIONS
V
CC
= 2.7 V to 16.5 V, T
A
= −40°C to +85°C, typical values at T
A
= 25°C, unless otherwise noted.
Table 1.
Parameter
V
CC
PIN
Operating Voltage Range
Supply Current
Undervoltage Lockout
Undervoltage Lockout Hysteresis
ON (ON-CLR) PIN
Input Current
Threshold
Threshold Hysteresis
SENSE PINS (SENSE+/SENSE−)
Hot Swap Operating Range
Input Current
Input Current
Circuit Breaker Limit Voltage
Circuit Breaker Limit Voltage
GATE PIN
Drive Voltage
Symbol
V
CC
I
CC
V
UVLO
V
UVLOHYS
I
INON
V
ON
V
ONHYST
Min
2.7
2.4
0.65
2.525
40
0
1.3
50
Typ
Max
16.5
0.8
2.65
Unit
V
mA
V
mV
µA
V
mV
V
µA
µA
mV
mV
V
V
V
V
V
μA
mA
mA
µA
µA
µA
µA
V
V
µA
V/V
V
µA
µs
µs
µs
Conditions
ADM1170
V
CC
rising
−1
1.22
+1
1.38
ON rising
I
INSENSE
I
INSENSE
V
CB
V
CB
V
GATE
1.6
−160
5
26
44
4.6
6.0
8.75
7.5
5.56
−6.5
−65
10
50
50
7.5
8
10
9
8
−12
4
25
−5
−60
2
100
1.3
0.2
10
20
1
50
2
40
40
16.5
+13
15
77
56
10
12
12
12
12
−14.5
V
SENSE+
= 1.6 V
V
SENSE+
≥ 2.2 V
V
CB
= (V
SENSE+
– V
SENSE−
), V
SENSE+
= 1.6 V
V
CB
= (V
SENSE+
– V
SENSE−
), V
SENSE+
≥ 2.2 V
V
GATE
− V
CC
, V
CC
= 3.0 V
V
GATE
− V
CC
, V
CC
= 3.3 V
V
GATE
− V
CC
, V
CC
= 5 V
V
GATE
− V
CC
, V
CC
= 12 V
V
GATE
− V
CC
, V
CC
= 15 V
V
GATE
= 0 V
V
GATE
= 3 V, V
CC
= 5 V, ON (ON-CLR) = low
V
GATE
= 3 V, V
CC
< UVLO
Initial cycle, V
TIMER
= 1 V
During current fault, V
TIMER
= 1 V
After Cct breaker tip, V
TIMER
= 1 V
Normal operation, V
TIMER
= 1 V
TIMER rising
TIMER falling
Pull-Up Current
Pull-Down Current
Pull-Down Current
TIMER PIN
Pull-Up Current
Pull-Down Current
Threshold High
Threshold Low
SS PIN
Soft Start Pull-Up Current
Current Setting Gain
Soft Start Completion Voltage
Pull-Down Current
t
OFF
Turn-Off Time (TIMER Rise to GATE Fall)
Turn-Off Time (ON Fall to GATE Fall)
Turn-Off Time (V
CC
Fall to IC Reset)
I
TIMERUP
I
TIMERDN
V
TIMERH
V
TIMERL
−2
−25
−8.5
−100
3.5
1.38
0.25
1.22
0.15
V
SS
/V
SENSE
During fault
V
TIMER
= 0 V to 2 V step, V
CC
= V
ON
= 5 V
V
ON
= 5 V to 0 V step, V
CC
= 5 V
V
CC
= 5 V to 2 V step, V
ON
= 5 V
Rev. A | Page 3 of 16
ADM1170
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
V
CC
Pin
SENSE+ Pin/SENSE− Pin
SENSE+ Pin − SENSE− Pin
TIMER Pin
ON (ON-CLR) Pin
SS Pin
GATE Pin
Storage Temperature Range
Operating Temperature Range
Lead Temperature (10 sec)
Junction Temperature
Rating
−0.3 V to +20 V
−0.3 V to +20 V
±5 V
−0.3 V to (V
CC
+ 0.3 V)
−0.3 V to +20 V
–0.3 V to (V
CC
+ 0.3 V)
−0.3 V to (V
CC
+ 11 V)
−65°C to +125°C
−40°C to +85°C
300°C
150°C
Data Sheet
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
θ
JA
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
8-Lead TSOT
θ
JA
152.9
Unit
°C/W
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.
Rev. A | Page 4 of 16
Data Sheet
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
ADM1170-1AUJ
TIMER
1
GND
2
8
ADM1170
ADM1170-2AUJ
V
CC
TIMER
1
GND
2
05124-006
8
V
CC
ON
4
5
GATE
ON-CLR
4
5
GATE
Figure 2. Pin Configuration, 1AUJ Model
Figure 3. Pin Configuration, 2AUJ Model
Table 4. Pin Function Descriptions
Pin No.
1
2
3
4
Mnemonic
TIMER
GND
SS
ON (ON-CLR)
Description
Timer Input Pin. The initial and circuit breaker timing cycles are set by this external capacitor. The initial timing
delay is 272.9 ms/μF, and 21.7 ms/µF for a circuit breaker delay. When the TIMER pin is pulled beyond the
upper threshold, the GATE turns off.
Chip Ground Pin.
Soft Start Pin. An external capacitor between the SS pin and GND sets the ramp rate of the current limit
reference.
Input Pin. The ON (ON-CLR) pin is an input to a comparator that has a low-to-high threshold of 1.3 V with
80 mV hysteresis and a glitch filter. The
ADM1170
is reset when the ON (ON-CLR) pin is low. When the ON
(ON-CLR) pin is high, the
ADM1170
is enabled. A rising edge on this pin has the added function of clearing a
fault and restarting the device on the latched off model, the
ADM1170-2.
Gate Output Pin. An internal charge pump provides a 12 µA pull-up current to drive the gate of an N-channel
MOSFET. In an overcurrent condition, the
ADM1170
controls the external FET to maintain a constant load
current.
Current Limit Sense Input Pins. The current limit is set via a sense resistor between the SENSE+ and SENSE−
pins. In an overcurrent condition, the gate of the FET is controlled to maintain the SENSE voltage at 50 mV.
When this limit is reached, the TIMER circuit breaker mode is activated. The circuit breaker limit can be
disabled by connecting the SENSE+ and SENSE− pins together.
Positive Supply Input Pin. The
ADM1170
operates between 2.7 V to 16.5 V. An undervoltage lockout (UVLO)
circuit with a glitch filter resets the
ADM1170
when the supply voltage drops below the specified UVLO limit.
5
6, 7
GATE
SENSE−, SENSE+
8
V
CC
Rev. A | Page 5 of 16
05124-007
7
SENSE+
TOP VIEW
SS
3
(Not to Scale)
6
SENSE–
7
SENSE+
TOP VIEW
SS
3
(Not to Scale)
6
SENSE–
