MAX4995AATA+T Maxim Integrated Products, MAX4995AATA+T Datasheet - Page 11

• Manufacturer Part Number: MAX4995AATA+T
• Description: IC SWITCH CURRENT LIMIT 8TDFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX4995AATA+T

• Function: Current Switch
• Accuracy: ±10%
• Voltage - Input: 1.7 ~ 5.5 V
• Current - Output: 600mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-TDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Sensing Method: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

A resistor from SETI to ground programs the current-limit
value for the MAX4995. Table 2 lists various current lim-
its set by different resistor values at SETI. Shorting SETI
to ground asserts FLAG.
Use the following formula to calculate the current limit:
Using an R
in a higher current limit. A programmed output current
greater than 660mA can damage the device.
Connecting any capacitance larger than 20pF to SETI
can cause instability.
Connect a capacitor from IN to GND to limit the input
voltage drop during momentary output short-circuit
conditions. Use a 1µF minimum ceramic capacitor for
proper device operation. Larger capacitor values
reduce the voltage undershoot at the input.
Due to the very fast current-limit reaction time of the
MAX4995AF, a larger input capacitance might need to
be connected at the input to dampen oscillation due to
long wires. Choose a value large enough to ensure IN
doesn’t exceed the absolute maximum ratings.
Table 2. Current Limit vs. Resistor Values
R
∞ (Open)
SETI
45.8
55.6
70.6
94.2
143
191
287
576
(kΩ)
SETI
R
SETI
Applications Information
with a value smaller than 45.8kΩ results
(k )
______________________________________________________________________________________
Ω
=
TYPICAL CURRENT LIMIT (mA)
Setting the Current Limit
2
I
LIM
9042( )
( A
m
V
)
−
2.48 k
Input Capacitor
602
500
397
300
200
150
100
50
0
(
50mA to 600mA Programmable
Ω
)
Current-Limit Switches
For stable operation over the full temperature range
and over the full programmable current-limit range, use
a 1µF ceramic capacitor from OUT to ground.
If the load capacitance is too large, then current may not
have enough time to charge the capacitance and the
device assumes that there is a faulty load condition.
Calculate the maximum capacitive load (C
can be connected to OUT using the following formula:
For example, for V
I
Due to the very fast current-limit reaction time of the
MAX4995AF, a larger output capacitance might need to
be connected at the output to dampen oscillation due
to long wires. Choose a value large enough to ensure
OUT doesn’t exceed the absolute maximum ratings.
To optimize the switch response time to output short-
circuit conditions, it is very important to keep all traces
as short as possible to reduce the effect of undesirable
parasitic inductance. Place input and output capacitors
as close as possible to the device. IN and OUT must be
connected with wide, short traces to the power bus.
During normal operation, the power dissipation is small
and the package temperature change is minimal. If the
output is continuously shorted to ground at the maxi-
mum supply voltage, the operation of the switches with
the autoretry option does not cause problems because
the total power dissipated during the short is scaled by
the duty cycle:
Attention must be given to the MAX4995C continuous
current-limit version when the power dissipation during
a fault condition may cause the device to reach thermal
shutdown threshold.
LIM
= 300mA, C
C
P
MAX
MAX
( F)
μ
=
Layout and Thermal Dissipation
V
MAX
IN(MAX)
=
IN
I
LIM
equals 909µF.
= 3.3V, t
t
(mA)
RETRY
×
I
OUT(MAX)
×
BLANK(MIN)
V (
+
t
BLANK(MIN)
IN
t
Output Capacitor
BLANK
V)
×
t
MAX
BLANK
= 10ms, and
(ms )
) value that
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