LTC4255
Quad Network Power
Controller with I
2
C Compatible Interface
FEATURES
s
s
DESCRIPTIO
s
s
s
s
s
s
Controls Four Independent –48V Power Channels
Each Channel has Separate Relay Drivers, ON/OFF
Control, Short-Circuit Protection with Current
Foldback, Open-Circuit Detection, and Power Good
Indication
Programmed via I
2
C
TM
Compatible Interface
Five Bit Programmable Digital Address Allows
Control of up to 32 LTC4255s (128 Channels)
Interrupt on FAULT Output can be used to Eliminate
Software Polling
Programmable Current Limit and Open-Circuit
Duration Periods
Programmable Latchoff or Autoretry after Short-
Circuit Faults
Programmable Autoretry Duty Cycle
The LTC
®
4255 is a quad –48V network power controller
with independent relay drivers and I
2
C compatible inter-
face. Each channel can be turned on and off via software
control, while providing short-circuit protection, open-
circuit detection, and power good indication. The short-
circuit protection includes a current foldback feature to
reduce power dissipation in the switch during shorts and
start-up.
The serial interface allows up to 128 channels to be
controlled with only two digital lines. A FAULT output can
be used as an interrupt line to eliminate fault detection by
software polling.
External switches and current sense resistors allow easy
scaling of current and power dissipation levels and pro-
vide the maximum protection against voltage and current
spikes.
The LTC4255 is available in the 28-pin SSOP package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
I
2
C is a trademark of Philips Electronics N.V.
APPLICATIO S
s
s
IP Phone Systems
DTE Power Distribution
TYPICAL APPLICATIO
12V
0.1µF
V
CC
SCL
SDA
FAULT
AD0
AD1
AD2
AD3
AD4
DGND AGND
V
EE
SENSE1 GATE1
RELAY3
RELAY4
OUT1 SENSE2 GATE2 OUT2 SENSE3 GATE3 OUT3 SENSE4 GATE4 OUT4
100k
Q1
R
S2
0.33Ω
Q2
R
S3
0.33Ω
Q3
Q1, Q2, Q3, Q4: FDC3612
RELAYS: V23079 SERIES
R
S4
0.33Ω
4255 TA01
LTC4255
–48V
R
S1
0.1µF 0.33Ω
100k
100k
Q4
4255f
U
RELAY1
RELAY2
100k
U
U
1
LTC4255
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
FAULT
SCL
SDA
AD4
AD3
AD2
AD1
AD0
RELAY1
1
2
3
4
5
6
7
8
9
28 OUT1
27 GATE1
26 SENSE1
25 OUT2
24 GATE2
23 SENSE2
22 V
EE
21 OUT3
20 GATE3
19 SENSE3
18 OUT4
17 GATE4
16 SENSE4
15 AGND
Supply Voltages
V
CC
to DGND ....................................................... 18V
V
EE
to AGND ...................................................... –80V
DGND to AGND ...................................................
±5V
Digital Pin Voltages
SCL, SDA, FAULT ........................ DGND – 0.3V to 6V
AD0-4 ....................................... DGND – 0.3V to 5.5V
Relay Driver Output Voltage
RELAY1-4 (Note 5) ...... DGND –0.3V to DGND + 15V
Analog Voltages
SENSE1-4 ............................... V
EE
– 0.3V to V
EE
+ 1V
OUT1-4 .................................. V
EE
– 80V to V
EE
+ 80V
Operating Temperature Range
LTC4255C ............................................... 0°C to 70°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LTC4255CG
RELAY2 10
RELAY3 11
RELAY4 12
DGND 13
V
CC
14
G PACKAGE
28-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 90°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 12V, V
EE
= –48V, AGND = DGND = 0V (Note 2)
SYMBOL
V
CC
I
CC
V
EE
I
EE
∆V
GND
V
LKO
∆V
GATE
I
GATE
V
SC
V
OC
V
PG
I
OUT
V
OLR
V
CLAMPR
V
OLD
PARAMETER
Positive Supply Voltage
Positive Supply Current
Negative Supply Voltage
Negative Supply Current
DC Ground Difference
V
EE
Undervoltage Lockout
External Gate Voltage (V
GATE
– V
EE
)
GATE Pin Output Current
Short-Circuit Sense Voltage
Open-Circuit Sense Voltage
Power_OK Threshold Voltage
OUT Pin Current
Relay Driver Output Low Voltage
Relay Driver Clamp Voltage
Digital Output Low Voltage
I
GATE
= –1µA
GATE On, V
GATE
= V
EE
GATE Off, V
GATE
= V
EE
+ 5V
(V
SENSE
– V
EE
), V
OUT
– V
EE
= 0V
(V
SENSE
– V
EE
)
(V
OUT
– V
EE
)
V
OUT
= V
EE
(V
RELAY
– DGND), I
RELAY
= 50mA, RELAY On
(V
RELAY
– DGND), I
RELAY
= 50mA,
RELAY Off (Note 5)
SDA, FAULT, I = 3mA
q
q
q
q
ELECTRICAL CHARACTERISTICS
DC Characteristics
CONDITIONS
V
CC
Referenced to DGND
Relays Off
All Relays On
V
EE
Referenced to AGND
AGND – DGND (Note 3)
MIN
10.8
TYP
12
2.1
10
–48
–1.9
MAX
13.2
3
15
–72
–3
5
UNITS
V
mA
mA
V
mA
V
V
V
µA
µA
mV
mV
V
µA
V
V
V
–5
–27
10
–30
30
125
1
1
13
–50
50
150
3
2
–1.4
15
–70
80
170
4.5
3
0.3
18
24
0.4
2
U
4255f
W
U
U
W W
W
LTC4255
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 12V, V
EE
= –48V, AGND = DGND = 0V
SYMBOL
V
ILD
V
IHD
R
PU
t
CL
PARAMETER
Digital Input Low Voltage
Digital Input High Voltage
AD0 to AD4 Pullup Resistors to 5V
Current Limit Filter Time
B5 = 0, B4 = 0, Figure 2
B5 = 0, B4 = 1
B5 = 1, B4 = 0
B5 = 1, B4 = 1
B7 = 0, B6 = 0
B7 = 0, B6 = 1
B7 = 1, B6 = 0
B7 = 1, B6 = 1
Figure 3
Figure 4
B3 = 0
B3 = 1
(Note 3)
Figure 1 (Notes 3, 4)
Figure 1 (Notes 3, 4)
Figure 1 (Notes 3, 4)
Figure 1 (Notes 3, 4)
Figure 1 (Notes 3, 4)
Figure 1 (Notes 3, 4)
Figure 1 (Notes 3, 4)
Figure 1 (Notes 3, 4)
Figure 1 (Notes 3, 4)
Figure 1 (Notes 3, 4)
Figure 1 (Notes 3, 4)
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
SCL, SDA
SCL, SDA
q
q
MIN
2.4
30
4.8
9.6
19.2
76.8
50
104
213
433
9.6
9.6
0.78
5.5
1.3
600
1.3
600
150
200
600
600
TYP
MAX
0.8
UNITS
V
V
kΩ
ms
ms
ms
ms
ms
ms
ms
ms
ms
ms
%
%
kHz
µs
ns
µs
ns
ns
ns
ns
ns
50
6
12
24
96
62
130
267
541
18
18
0.83
6
90
7.2
14.4
28.8
115.2
74
156
320
649
28.8
28.8
0.89
6.7
400
AC Characteristics
t
OCD
Open-Circuit Enable Delay
After Power_OK
t
OCF
t
OD
DC
R
t
SCLK
t
1
t
2
t
3
t
4
t
5
t
6
t
7
t
8
t
9
t
r
t
f
Open-Circuit Filter Time
Turn-On Delay Time
Retry Duty Cycle
Clock Frequency
Bus Free Time
Start Hold Time
SCL Low Time
SCL High Time
Data Hold Time
Data Setup Time
Start Setup Time
Stop Setup Time
Stop to Fault Clear
SCL, SDA Rise Time
SCL, SDA Fall Time
300
20
20
300
150
ns
ns
ns
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to ground unless otherwise
specified.
Note 3:
Guaranteed by design, not subject to test.
Note 4:
Values referred to V
ILD
and V
IHD
.
Note 5:
A Zener diode clamps the relay drivers at 18V (RELAY 1-4).
4255f
3
LTC4255
TYPICAL PERFOR A CE CHARACTERISTICS
I
CC
vs V
CC
(Relays Off)
1.290
T
A
= 25°C
9.8
9.6
9.4
I
CC
(mA)
1.280
I
CC
(mA)
I
CC
(mA)
1.270
1.260
1.250
1.240
10.8
11.3
12.3
11.8
V
CC
(V)
I
CC
vs Temperature (Relays On)
9.6
9.5
9.4
9.3
I
CC
(mA)
V
CC
= 12V
9.2
9.1
9.0
I
EE
(mA)
–1.2
–1.6
8.9
8.8
–50
–25
50
TEMPERATURE (°C)
0
25
75
100
4255 G04
–2.0
–80
I
EE
(mA)
V
SC
vs V
OUT
160
140
120
V
SC
(mV)
V
OC
(mV)
V
SC
(mV)
100
80
60
40
20
0
–50
–40
–20
–30
V
OUT
(V)
–10
0
4255 G07
4
U W
12.8
T
A
= 25°C
I
CC
vs V
CC
(Relays On)
T
A
= 25°C
1.34
1.32
1.30
1.28
1.26
1.24
I
CC
vs Temperature (Relays Off)
V
CC
= 12V
9.2
9.0
8.8
8.6
10.8
1.22
1.20
–50
13.3
4255 G01
11.3
11.8
12.3
V
CC
(V)
12.8
13.3
4255 G02
–25
50
TEMPERATURE (°C)
0
25
75
100
4255 G03
I
EE
vs V
EE
0
–1.88
I
EE
vs Temperature
V
EE
= –48V
T
A
= 25°C
–1.90
–0.4
–0.8
–1.92
–1.94
–1.96
–60
–40
V
EE
(V)
–20
0
4255 G05
–1.98
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
4255 G06
V
SC
vs Temperature
165
160
155
150
145
140
135
–50
V
OUT
= V
EE
3.20
3.15
3.10
3.05
3.00
2.95
V
OC
vs Temperature
–25
0
25
50
TEMPERATURE (°C)
75
100
4255 G08
2.90
–50
–25
25
50
0
TEMPERATURE (°C)
75
100
4255 G09
4255f
LTC4255
TYPICAL PERFOR A CE CHARACTERISTICS
I
OUT
vs V
OUT
0
–0.2
–0.4
I
GATE
(µA)
I
OUT
(µA)
I
OUT
(µA)
–0.6
–0.8
–1.0
–1.2
–1.4
–1.6
–50
–40
–20
–30
V
OUT
(V)
I
GATE
vs Temperature
65
60
55
I
GATE
(µA)
V
GATE
(V)
GATE OFF
V
GATE
= V
EE
+ 5V
13.0
12.8
12.6
12.4
12.2
–50
I
SENSE
(µA)
50
45
40
35
–50
–25
0
25
50
TEMPERATURE (°C)
V
EE
Undervoltage Lockout
vs Temperature
–26
V
EE
UNDERVOLTAGE LOCKOUT (V)
–27
–28
V
OL
(V)
R
PU
(kΩ)
–29
–30
–31
–32
–50
–25
0
25
50
TEMPERATURE (°C)
U W
T
A
= 25°C
V
EE
= –48V
–10
I
OUT
vs Temperature
2.0
1.8
1.6
1.4
1.2
1.0
0.8
–50
V
OUT
= V
EE
–44
–46
–48
–50
–52
–54
–56
I
GATE
vs Temperature
GATE ON
V
GATE
= V
EE
0
4255 G10
–25
0
25
50
TEMPERATURE (°C)
75
100
4255 G11
–58
–50
–25
50
25
0
TEMPERATURE (°C)
75
100
4255 G12
V
GATE
vs Temperature
13.6
13.4
13.2
–42
–43
–44
–45
–46
–47
I
SENSE
vs Temperature
V
SENSE
= V
EE
75
100
4255 G13
–25
50
25
0
TEMPERATURE (°C)
75
100
4255 G14
–48
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
4255 G15
Relay Driver Output Low Voltage
(V
OLR
) vs Temperature
0.170
0.165
0.160
0.155
0.150
0.145
0.140
0.135
I
RELAY
= 50mA
60
59
58
57
56
55
54
53
52
–25
25
50
0
TEMPERATURE (°C)
75
100
4255 G17
AD0-4 Pullup Resistors to 5V (R
PU
)
vs Temperature
75
100
4255 G16
0.130
–50
51
–50
50
0
TEMPERATURE (°C)
100
4255 G18
4255f
5
京公网安备 11010802033920号
EEWORLD
