MAX4995AATA+T Maxim Integrated Products, MAX4995AATA+T Datasheet - Page 9

• 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

The MAX4995A/MAX4995AF/MAX4995AL/MAX4995B/
MAX4995C programmable current-limit switches oper-
ate from +1.7V to +5.5V and provide internal current
limiting adjustable from 50mA to 600mA. These devices
feature a fixed blanking time and a FLAG output that
notifies the processor when a fault condition is present.
A resistor from SETI to GND programs the current limit
for the switch (see the Setting the Current Limit sec-
tion). If the output current exceeds the current limit for a
time equal to or longer than t
asserts and the MAX4995A/MAX4995AF/MAX4995AL
enter the autoretry mode. The MAX4995B latches off
the switch, and the MAX4995C enters the continuous
current-limit mode.
When the forward current reaches the current-limit
threshold, the t
FLAG asserts if the overcurrent-limit condition is pre-
sent for t
dition disappears before the blanking time (t
elapsed. A retry time delay (t
after the blanking time has elapsed and during that
time, the switch latches off. At the end of t
switch turns on again. If the fault still exists, the cycle
repeats. If the fault has been removed, the switch stays
on. During this cycle, FLAG stays low. In autoretry if
the thermal power rating of the package is exceeded,
the MAX4995A/MAX4995AF/MAX4995AL go into ther-
mal shutdown.
The autoretry feature saves system power in case of an
overcurrent or short-circuit condition. During t
time when the switch is on, the supply current is held at
the current limit. During time t
off, the current through the switch is zero. Thus, the
average output current is much less than the pro-
grammed current limit. Calculate the average output
current using the following equation:
With a typical t
524ms, the duty cycle is 3%, resulting in a 97% power
savings over the switch being on the entire time.
I
LOAD
BLANK
Autoretry (MAX4995A/MAX4995AF/
= I
BLANK
. The timer resets if the overcurrent con-
BLANK
LIM
_______________________________________________________________________________________
Programmable Current Limit
[t
BLANK
timer begins counting (Figure 2).
Detailed Description
= 16.3ms and typical t
/(t
RETRY
RETRY
BLANK
BLANK
) starts immediately
when the switch is
+ t
, the output flag
MAX4995AL)
RETRY
50mA to 600mA Programmable
BLANK
RETRY
)]
RETRY
BLANK
) has
, the
=
Current-Limit Switches
When the forward current reaches the current-limit
threshold, the t
FLAG asserts if an overcurrent-limit condition is present
for greater than t
current condition disappears before t
elapsed. The switch turns off if the overcurrent condition
continues beyond the blanking time. Reset the switch
by either toggling the control logic (ON) or cycling the
input voltage. If the thermal power rating of the pack-
age is exceeded during t
into thermal shutdown.
When the forward current reaches the forward current-
limit threshold, the MAX4995C limits the output current
to the programmed current limit. FLAG asserts if the
current limit is present for t
the overload condition is removed. In this mode, if the
thermal power rating of the package is exceeded, the
MAX4995C goes into thermal shutdown.
The ON input for the MAX4995_/MAX4995AF and ON
input for the MAX4995AL control the switch; see Table
1. Toggle ON for the MAX4995B to reset the fault condi-
tion once the short current is detected and the device
shuts down.
The MAX4995 features a reverse-current protection cir-
cuit that limits the backflow current to 10µA when the
output voltage exceeds the input voltage by 110mV
(typ). The switch turns off and FLAG asserts without
waiting for t
and FLAG deasserts when the output voltage drops
below the detecting threshold by 10mV (typ).
Table 1. Switch Truth Table
MAX4995AF
MAX4995_/
Continuous Current Limit (MAX4995C)
ON
0
1
BLANK
BLANK
BLANK
to elapse. The switch turns back on
Reverse-Current Protection
MAX4995AL
timer begins counting (Figure 3).
time. The timer resets if the over-
BLANK
ON
1
0
Switch-On/Off Control
BLANK
Latchoff (MAX4995B)
, the MAX4995B goes
and deasserts when
SWITCH
STATUS
BLANK
Off
On
has
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