Electrical characteristics (continued) – Rainbow Electronics MAX5943 User Manual
Page 4
MAX5943
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)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
TIM = IN or
TIM ≥ 3.4V
0.45
0.51
0.57
ms
R
TIM
= 4k
Ω
27
32.5
38
µs
R
TIM
= 50k
Ω
228
345
403
µs
Circuit-breaker mode,
MAX5943B
TIM = floating
3.75
5.5
7
ms
TIM = IN or
TIM ≥ 3.4V
0.89
1.00
1.13
ms
R
TIM
= 4k
Ω
54
65
76
µs
R
TIM
= 50k
Ω
575
690
806
µs
Circuit-breaker mode,
MAX5943C
TIM = floating
7.5
10.9
14
ms
TIM = IN
1.78
2.02
2.26
ms
R
TIM
= 4k
Ω
109
130
151
µs
R
TIM
= 50k
Ω
1.15
1.38
1.61
ms
Circuit-breaker mode,
MAX5943D
TIM = floating
15
21.9
28
ms
TIM = IN or
TIM ≥ 3.4V
3.56
4.05
4.52
ms
R
TIM
= 4k
Ω
217
260
303
µs
R
TIM
= 50k
Ω
2.3
2.76
3.23
ms
Circuit-Breaker Timeout
(MAX5943B–MAX5943E) (Note 7)
t
CB
Circuit-breaker mode,
MAX5943E
TIM = floating
30
44
56
ms
Automatic Restart Delay After
Current-Limit/Circuit-Breaker
Timeout
t
OFF
LATCH = GND (Note 8)
128 x
(t
ILIM
OR
t
CB)
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
t
ON_OFF
Time from V
ON
< (V
ON_OFF
- Hysteresis)
until (V
GATE2
- V
OUT
) < 1V, GATE2 = open
(Note 9)
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/Circuit-Breaker Timeout; IN or ON low.
Note 5:
See the Typical Operating Circuit. Measured at V
GATE1
= V
SENSE
.
Note 6:
The tristate (“floating”) logic condition will be entered if the pin current is within these limits.
Note 7:
R
TIM
is connected from TIM to GND. The maximum timeout period is enforced to prevent arbitrarily long operation in cur-
rent-limit mode. Therefore, the relationship between resistor value and timeout changes for large values of R
TIM
. See
Current-Limit Timeout vs. R
TIM
in the Typical Operating Characteristics for nominal values.
Note 8:
Parameter t
OFF
is a direct multiple of t
ILIM
(or t
CB
), so the limits for t
OFF
track the limits for t
ILIM
(or t
CB
).
Note 9:
If the ON voltage goes below V
ON_REF
- Hysteresis, then GATE2 goes low immediately to disconnect power from the load
quickly (within t
ON_OFF
).