MAX5943CEEE+T Maxim Integrated Products, MAX5943CEEE+T Datasheet - Page 12

• Manufacturer Part Number: MAX5943CEEE+T
• Description: IC FIREWIRE CURR LIMITER 16-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX5943CEEE+T

• Applications: FireWire® Apps
• Fet Type: N-Channel
• Number Of Outputs: 2
• Internal Switch(s): No
• Delay Time - Off: 100ns
• Voltage - Supply: 7.5 V ~ 37 V
• Current - Supply: 1.3mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Delay Time - On: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

FireWire Current Limiter and Low-Drop
ORing Switch Controller
The MAX5943B–MAX5943E provide a circuit-breaker
function that protects against excessive load currents
and short-circuit conditions. The load current is monitored
by sensing the voltage across an external sense resistor
(R
source when the voltage across R
the programmed circuit-breaker thresholds (V
longer than the circuit-breaker timeout period, t
Unlike the MAX5943A, when an output short circuit or
overcurrent occurs, the MAX5943B–MAX5943E keep
GATE2 fully enhanced. The short-circuit current is limit-
ed only by the input source impedance, R
R
the power path. If the excessive current condition per-
sists (as indicated by V
GATE2 turns off with a strong pulldown (I
quickly disconnect the power source from the load and
FAULT asserts low (Figure 3).
Exercise caution when using the MAX5943B–MAX5943E.
Unlike the MAX5943A, the MAX5943B–MAX5943E do not
limit the load current during t
may cause damage to external devices connected in the
power path.
Figure 3. MAX5943B–MAX5943E Circuit-Breaker Timing Diagram
12
DS(ON),
SENSE
______________________________________________________________________________________
V
V
V
FAULT
GATE1
GATE2
V
I
OUT
OUT
) and disconnects the load from the power
Q2’s R
MAX5943B–MAX5943E Circuit Breaker
DS(ON)
V
G2
, and any parasitic impedance in
IS
> V
CB
V
t
G2
CB
. High current during t
TH
) for longer than t
SENSE
I
, V
LIMIT
V
SENSE
IS
IN
G2 OFF
CB
, exceeds
.
TH
, Q1’s
) for
) to
CB
CB
,
The MAX5943 allows three selectable current-limit/cir-
cuit-breaker thresholds (V
threshold by connecting ILIM to the appropriate level;
see Table 1.
The MAX5943’s current-limit/circuit-breaker timeout
function disconnects power from the load if the current-
limit or circuit-breaker threshold voltage exceeds its
maximum limit for a programmable amount of time.
Connect TIM to IN for the MAX5943 default timeout
periods (see Table 2).
Adjust the fault timeout period (t
ing a resistor (R
Operating Characteristics ). Calculate the fault-limit
timeout period using the following equation:
where R
MAX5943A, K = 32 for MAX5943B, K = 16 for
MAX5943C, K = 8 for MAX5943D, and K = 4 for the
MAX5943E.
Table 1. Current-Limit/Circuit-Breaker
Trip Threshold Level
Table 2. MAX5943_ Timeout Periods
MAX5943A
MAX5943B
MAX5943C
MAX5943D
MAX5943E
PART
Current-Limit/Circuit-Breaker Thresholds
ILIM CONNECTION
t
ILIM
TIM
Open
GND
(
TIMEOUT,
ms
is in kΩ, t
DEFAULT
IN
TIM = IN
(ms)
)
0.5
TIM
2
1
2
4
=
Current-Limit/Circuit-Breaker
t
CB
) from TIM to GND (see the Typical
Timeout Period (t
ILIM
(
ms
(4kΩ < R
PROGRAMMABLE
TIMEOUT RANGE
1.04ms to 11.05ms
130µs to 1.38ms
260µs to 2.76ms
32.5µs to 345µs
)
/t
65µs to 690µs
=
CB
TH
0 25
.
). Choose the voltage
is in ms, and K = 1 for
TIM
ILIM/
×
< 50kΩ)
V
R
t
CB
TH
TIM
40
50
60
) by connect-
(mV)
K
(
ILIM
FLOATING
k
MAXIMUM
TIMEOUT,
Ω
TIM =
)
(ms)
19.2
38.4
175
4.8
9.6
/t
CB
)