MAX5944
Dual FireWire Current Limiter and Low-Drop
ORing Switch Controller
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 7.5V to 37V, GND = 0V, and T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
IN_
= 12V, T
A
= +25°C.)
(Note 1)
SYMBOL
MIN TYP MAX
TIMING
Current-Limit Timeout t
ILIM
Current-limit mode
1.78 2.02 2.26
ms
Automatic Restart Delay After
Current-Limit Timeout (Note 7)
t
OFF
240 259 278
ms
GATE1_ Turn-Off Time
(ORing Response Time)
t
OR
From V
OR
trigger until
(V
GATE1_
- V
IN_
) < 1V, C
GATE1_
= 10nF
100
ns
Turn-Off Response Time
(Note 7)
t
ON_OFF
Time from V
ON_
< (V
ON_OFF
- Hysteresis)
until (V
GATE2_
- V
OUT_
) < 1V,
for C
GATE2_
= open
0.34
0.6 µs
Minimum Delay from ON_ Low to
Low-Current Shutdown Mode
t
SD
ON_ step from 1.3V to 0.4V 50 µs
Note 1: All min/max parameters are tested at +25°C and +85°C. Limits at -40°C are guaranteed by design.
Note 2: Measured at both V
GATE2
= V
OUT
= 0V and V
GATE2
= V
OUT
= V
IN
.
Note 3: The typical value of parameter V
THF
is 1.5 x V
TH
.
Note 4: Current-Limit Timeout. IN_ or ON_ low.
Note 5: See the Typical Operating Circuit. Measured at V
GATE_
= V
SENSE_
.
Note 6: The tristate (“floating”) logic condition will be entered if the pin current is within these limits.
Note 7: If the ON_ voltages go below V
ON_REF
- Hysteresis, then GATE2_ goes low immediately to disconnect power from the load
quickly (within t
ON_OFF
).
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5944 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
353020 251510
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
1.0
540
T
A
= +85
°
C
T
A
= +25
°
C
T
A
= -40°C
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5944 toc02
SUPPLY VOLTAGE (V)
SHUTDOWN SUPPLY CURRENT (µA)
353020 251510
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
0
540
CURRENT-LIMIT/CIRCUIT-BREAKER
THRESHOLD VOLTAGE vs. TEMPERATURE
MAX5944 toc03
TEMPERATURE (°C)
THRESHOLD VOLTAGE (mV)
603510-15
46.5
47.0
47.5
48.0
48.5
49.0
49.5
50.0
50.5
51.0
51.5
52.0
46.0
-40 85
V
IN
= 32V
V
IN
= 12V
V
IN
= 7.5V
Typical Operating Characteristics
(V
IN_
= +12V, T
A
= +25°C, unless otherwise noted.)
