safely inserted and removed from a live backplane. Using
an external N-channel pass transistor, the board supply
voltage can be ramped up at an adjustable rate. An I
2
C
interface and onboard ADC allow monitoring of board
current, voltage and fault status.
The device features adjustable analog foldback current
limit with latch off or automatic restart after the LTC4260
remains in current limit beyond an adjustable time-out
delay.
The controller has additional features to interrupt the host
when a fault has occurred, notify when output power is
good, detect insertion of a load card and power-up in
either the on or off state.
L,
LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
Allows Safe Board Insertion into Live Backplane
8-Bit ADC Monitors Current and Voltage
I
2
C™/SMBus Interface
Wide Operating Voltage Range: 8.5V to 80V
High Side Drive for External N-Channel MOSFET
Input Overvoltage/Undervoltage Protection
Optional Latchoff or Autoretry After Faults
Alerts Host After Faults
Foldback Current Limiting
Available in 24-Lead SO, 24-Lead Narrow
SSOP and 32-Lead (5mm
×
5mm) QFN Packages
applicaTions
n
n
n
Electronic Circuit Breakers
Live Board Insertion
Computers, Servers
Typical applicaTion
3A, 48V Card Resident Application
48V
49.9k
0.1µF
CONNECTOR 2
CONNECTOR 1
1.74k
*
2.67k
0.010
FDB3632
Power Up Waveforms
+
V
OUT
48V
C
L
43.5k
3.57k
V
IN
50V/DIV
I
IN
2A/DIV
C
L
= 1000F
10
100k
6.8nF
SDA
SCL
ALERT
UV V
DD
SENSE GATE
OV
SDAO
SDAI
LTC4260
SCL
ALERT
ON
INTV
CC
TIMER
0.1µF
68nF
SOURCE
FB
BD_PRST
ADIN
GND
GPIO
4260 TA01
V
OUT
50V/DIV
24k
GPIO
5V/DIV
25ms/DIV
4260 TA02
GND
BACKPLANE PLUG-IN
CARD
*DIODES INC. SMBT70A
4260fc
For more information
www.linear.com/LTC4260
1
LTC4260
absoluTe MaxiMuM raTings
(Notes 1, 2)
Supply Voltages (V
DD
) .............................– 0.3V to 100V
Input Voltages
SENSE ..............................V
DD
– 10V or –0.3V to V
DD
SOURCE............................ GATE – 5V to GATE + 0.3V
BD_PRST, FB, ON, OV, UV ...................... –0.3V to 12V
ADR0-ADR2, TIMER, ADIN ........–0.3V to INTV
CC
+ 0.3V
SCL, SDAI ............................................ –0.3V to 6.5V
Output Voltages
GPIO .................................................... –0.3V to 100V
GATE (Note 3) ..................................... –0.3V to 100V
ALERT,
SDAO ............................................ –0.3V to 6.5V
Supply Voltage (INTV
CC
) .......................... –0.3V to 6.2V
Operating Temperature Range
LTC4260C ................................................ 0°C to 70°C
LTC4260I.............................................. –40°C to 85°C
Storage Temperature Range
GN, SW Packages ..............................– 65°C to 150°C
UH Package ....................................... –65°C to 125°C
Lead Temperature (Soldering, 10 sec)
GN, SW Packages Only ..................................... 300°C
pin conFiguraTion
SENSE
SENSE
V
DD
NC
UV
OV
GND
ON
SCL
SDAI
1
2
3
4
5
6
7
8
9
24 GATE
23 SOURCE
22 NC
21 NC
20 GPIO
19 INTV
CC
18 FB
17 ADR2
16 ADR1
15 ADR0
14 BD_PRST
13 ADIN
SENSE 1
V
DD
2
NC 3
NC 4
UV 5
GND 6
ON 7
SCL 8
SDAI 9
SDAO 10
ALERT
11
TIMER 12
SW PACKAGE
24-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 75°C/W
24 GATE
23 SOURCE
22 NC
21 NC
20 GPIO
19 INTV
CC
18 FB
17 ADR2
16 ADR1
15 ADR0
14 BD_PRST
13 ADIN
NC 1
NC 2
NC 3
UV 4
OV 5
GND 6
ON 7
SCL 8
9 10 11 12 13 14 15 16
TIMER
SDAO
ALERT
ADIN
SDAI
BD_PRST
ADR0
ADR1
33
GATE
V
DDK
V
DD
TOP VIEW
TOP VIEW
SOURCE
24 NC
23 NC
22 NC
21 NC
20 GPIO
19 INTV
CC
18 FB
17 ADR2
TOP VIEW
NC
NC
NC
32 31 30 29 28 27 26 25
SDAO 10
ALERT
11
TIMER 12
GN PACKAGE
24-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 85°C/W
UH PACKAGE
32-LEAD (5mm
×
5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 34°C/W
EXPOSED PAD (PIN 33) PCB ELECTRICAL CONNECTION OPTIONAL
orDer inForMaTion
LEAD FREE FINISH
LTC4260CGN#PBF
LTC4260IGN#PBF
LTC4260CSW#PBF
LTC4260ISW#PBF
LTC4260CUH#PBF
LTC4260IUH#PBF
TAPE AND REEL
LTC4260CGN#TRPBF
LTC4260IGN#TRPBF
LTC4260CSW#TRPBF
LTC4260ISW#TRPBF
LTC4260CUH#TRPBF
LTC4260IUH#TRPBF
PART MARKING*
LTC4260CGN
LTC4260IGN
LTC4260CSW
LTC4260ISW
4260
4260
PACKAGE DESCRIPTION
24-Lead Plastic SSOP
24-Lead Plastic SSOP
24-Lead Plastic SO
24-Lead Plastic SO
32-Lead (5mm
×
5mm) Plastic QFN
32-Lead (5mm
×
5mm) Plastic QFN
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
4260fc
2
For more information
www.linear.com/LTC4260
LTC4260
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
DD
= 48V, unless otherwise noted.
SYMBOL
General
V
DD
I
DD
V
DD(UVL)
INTV
CC(UVL)
INTV
CC
Gate Drive
t
D
ΔV
GATE
I
GATE(UP)
I
GATE(FST)
I
GATE(DN)
I
SOURCE
Input Pins
V
ON(TH)
ΔV
ON(HYST)
I
ON(IN)
V
OV(TH)
ΔV
OV(HYST)
I
OV(IN)
V
UV(TH)
ΔV
UV(HYST)
I
UV(IN)
V
UV(RTH)
ΔV
UV(RHYST)
ΔV
SENSE(TH)
I
SENSE(IN)
V
FB
ΔV
FB(HYST)
I
FB
V
BD_PRST(TH)
I
BD_PRST
V
GPIO(TH)
ΔV
GPIO(HYST)
V
GPIO(OL)
I
GPIO(IN)
R
ADIN
I
ADIN
ON Pin Threshold Voltage
ON Pin Hysteresis
ON Pin Input Current
OV Pin Threshold Voltage
OV Pin Hysteresis
OV Pin Input Current
UV Pin Threshold Voltage
UV Pin Hysteresis
UV Pin Input Current
UV Pin Reset Threshold Voltage
UV Pin Reset Threshold Hysteresis
Current Limit Sense Voltage Threshold
(V
DD
– V
SENSE
)
SENSE Pin Input Current
Foldback Pin Power Good Threshold
FB Pin Power Good Hysteresis
Foldback Pin Input Current
BD_PRST Input Threshold
BD_PRST Pullup Current
GPIO Pin Input Threshold
GPIO Pin Hysteresis
GPIO Pin Output Low Voltage
GPIO Pin Input Leakage Current
ADIN Pin Input Resistance
ADIN Pin Input Current
I
GPIO
= 2mA
V
GPIO
= 80V
V
ADIN
= 1.28V
V
ADIN
= 2.56V
l
l
l
l
elecTrical characTerisTics
PARAMETER
Input Supply Range
Input Supply Current
V
DD
Supply Undervoltage Lockout
V
CC
Supply Undervoltage Lockout
Internal Regulator Voltage
Turn-On Delay
External N-Channel Gate Drive
(V
GATE
– V
SOURCE
)
External N-Channel Pull-Up Current
External N-Channel Fast Pull-Down
External N-Channel Pull-Down Current
SOURCE Pin Input Current
CONDITIONS
l
l
MIN
8.5
TYP
MAX
80
UNITS
V
mA
V
V
V
ms
V
V
µA
mA
mA
µA
V
mV
µA
V
mV
µA
V
mV
µA
V
mV
mV
mV
µA
V
mV
µA
V
mV
µA
V
mV
V
µA
MΩ
µA
2
7
3.4
5
50
10
4.5
–14
300
0.7
200
1.19
60
3.43
70
3.43
310
1.18
80
45
10
70
3.43
80
1.2
70
–7
1.6
7.45
3.8
5.5
100
14
6
–18
600
1
400
1.235
130
0
3.5
90
0
3.5
380
0
1.235
160
50
20
100
3.5
100
0
1.235
130
–10
1.8
80
0.25
0
2
10
0
5
7.9
4.2
6
150
18
18
–22
1000
1.4
600
1.27
200
±1
3.56
120
±1
3.56
440
±2
1.27
250
55
30
130
3.56
120
±2
1.27
190
–16
2
0.5
±10
±1
V
DD
Falling
INTV
CC
Falling
l
l
l
l
V
DD
= 20V to 80V
V
DD
= 8.5V to 20V
Gate Drive On, V
GATE
= 0V
Fast Turn Off, V
GATE
= 48V, V
SOURCE
= 43V
Gate Drive Off, V
GATE
= 58V, V
SOURCE
= 48V
SOURCE = 48V
V
ON
Rising
V
ON
= 1.2V
V
OV
Rising
V
OV
= 3.5V
V
UV
Rising
V
UV
= 3.5V
V
UV
Falling
V
FB
= 3.5V
V
FB
= 0V
V
SENSE
= 48V
FB Rising
FB = 3.5V
V
BD_PRST
Rising
BD_PRST = 0V
V
GPIO
Rising
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
ΔV
BD_PRST(HYST)
BD_PRST Hysteresis
4260fc
For more information
www.linear.com/LTC4260
3
LTC4260
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
DD
= 48V, unless otherwise noted.
SYMBOL
Timer
V
TIMER(H)
V
TIMER(L)
I
TIMER(UP)
I
TIMER(DN)
I
TIMER(RATIO)
AC Parameters
t
PLH(GATE)
t
PHL(GATE)
t
PHL(SENSE)
ADC
Resolution (No Missing Codes)
Integral Nonlinearity
(Note 4)
V
DD
– SENSE (Note 5)
SOURCE
ADIN
V
DD
– SENSE
SOURCE
ADIN
(Note 6)
(Note 6)
V
DD
– SENSE (Note 6)
SOURCE
ADIN
l
l
l
l
l
l
l
l
l
l
l
l
elecTrical characTerisTics
PARAMETER
TIMER Pin High Threshold
TIMER Pin Low Threshold
TIMER Pin Pull-Up Current
TIMER Pin Pull-Down Current
TIMER Pin Current Ratio
I
TIMER(DN)
/I
TIMER(UP)
Input High (ON) to GATE High
Propagation Delay
CONDITIONS
V
TIMER
Rising
V
TIMER
Falling
V
TIMER
= 0V
V
TIMER
= 1.3V
l
l
l
l
l
MIN
1.2
0.1
–80
1.4
1.6
TYP
1.235
0.2
–100
2
2
MAX
1.28
0.3
–120
2.6
2.7
UNITS
V
V
µA
µA
%
C
GATE
= 1pF
l
l
l
1
0.5
0.4
8
±0.5
±0.5
±0.5
3
3
1
µs
µs
µs
Bits
Input High (OV, BD_PRST), Input Low
C
GATE
= 1pF
(ON, UV) to GATE Low Propagation Delay
(V
DD
– SENSE) High to GATE Low
V
DD
– SENSE = 200mV, C
GATE
= 10nF
±2
±1.25
±1.25
±1.5
±1
±1
±5
±5
LSB
LSB
LSB
LSB
LSB
LSB
LSB
LSB
mV
V
V
Hz
Offset Error
Full Scale Error
Total Unadjusted Error
Full Scale Voltage (Code 255)
75
100
2.50
76.5
102
2.55
10
78
104
2.60
Conversion Rate
I
2
C Interface
V
ADR(H)
V
ADR(L)
I
ADR(IN)
V
SDAI,SCL(TH)
I
SDAI,SCL(IN)
V
SDAO(OL)
V
ALERT(OL)
I
SDAO,ALERT(IN)
ADR0 to ADR2 Input High Voltage
Threshold
ADR0 to ADR2 Input Low Voltage
Threshold
ADR0 to ADR2 Input Current
SDAI, SCL Input Threshold
SDAI, SCL Input Current
SDAO Output Low Voltage
ALERT
Output Low Voltage
SDAO,
ALERT
Input Current
SCL, SDAI = 5V
I
SDAO
= 5mA
I
ALERT
= 5mA
SDAO,
ALERT
= 5V
ADR0 to ADR2 = 0V, 5.5V
l
l
l
l
l
l
INTV
CC
–0.6
0.25
–80
1.6
INTV
CC
–0.45
0.45
INTV
CC
–0.25
0.65
80
V
V
µA
V
µA
V
V
µA
1.8
0
0.2
0.2
0
2
±1
0.4
0.4
±1
4260fc
4
For more information
www.linear.com/LTC4260
LTC4260
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
DD
= 48V, unless otherwise noted.
SYMBOL
f
SCL(MAX)
t
BUF(MIN)
t
SU,STA(MIN)
t
HD,STA(MIN)
t
SU,STO(MIN)
t
SU,DAT(MIN)
t
HD,DATI(MIN)
t
HD,DATO(MIN)
t
SP(MAX)
C
X
PARAMETER
Maximum SCL Clock Frequency
Minimum Bus Free Time Between
Stop/Start Condition
Minimum Repeated Start Condition
Set-Up Time
Minimum Hold Time After (Repeated)
Start Condition
Minimum Stop Condition Set-Up Time
Minimum Data Set-Up Time Input
Minimum Data Hold Time Input
Minimum Data Hold Time Output
Maximum Suppressed Spike Pulse Width
SCL, SDA Input Capacitance
SDAI Tied to SDAO
300
50
CONDITIONS
Operates with f
SCL
≤ f
SCL(MAX)
MIN
400
0.12
30
140
30
30
–100
500
110
5
1.3
600
600
600
100
0
900
250
10
TYP
MAX
UNITS
kHz
µs
ns
ns
ns
ns
ns
ns
ns
pF
I
2
C Interface Timing (Note 4)
elecTrical characTerisTics
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to GND unless otherwise
specified.
Note 3:
Limits on maximum rating is defined as whichever limit occurs first.
An internal clamp limits the GATE pin to a minimum of 10V above source.
Driving this pin to voltages beyond the clamp may damage the device.
Note 4:
Guaranteed by design and not subject to test.
Note 5:
Integral nonlinearity is defined as the deviation of a code from a
precise analog input voltage. Maximum specifications are limited by the
LSB step size and the single shot measurement. Typical specifications are
measured from the 1/4, 1/2 and 3/4 areas of the quantization band.
Note 6:
For the V
DD
-SENSE channel, full-scale is at code 255 but codes
above 200 may be discarded by offset cancellation. Full scale error and
total unadjusted error are evaluated over the 0-200 code range. Full scale
voltage corresponds to the theoretical code 255, and is extrapolated from
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