MAX4794EUS+T Maxim Integrated Products, MAX4794EUS+T Datasheet - Page 7

• Manufacturer Part Number: MAX4794EUS+T
• Description: IC SWITCH 1X1 SOT143-4
• Manufacturer: Maxim Integrated Products

Specifications of MAX4794EUS+T

• Function: Switch
• Circuit: 1 x 1:1
• On-state Resistance: 400 mOhm
• Voltage Supply Source: Single Supply
• Voltage - Supply, Single/dual (±): 2.3 V ~ 5.5 V
• Current - Supply: 80µA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-143, SOT-143B, TO-253AA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: MAX4794EUS+T; MAX4794EUS+TTR

off. FLAG is an open-drain output transistor and requires
an external pullup resistor from FLAG to IN. During shut-
down (ON is low), the pulldown on FLAG output is
released in order to limit power dissipation. FLAG goes
low when any of the following conditions occur:
• The die temperature exceeds the thermal-shutdown
• The device is in current limit for more than the fault-
• V
When the forward or reverse current-limit threshold is
exceeded, t
The timer resets if the overcurrent condition disappears
before t
is started immediately after t
during that time, the switch is latched off. At the end of
t
exists, the cycle is repeated. If the fault has been
removed, the switch stays on.
The autoretry feature saves system power in the case of
an overcurrent or short-circuit condition. During t
when the switch is on, the supply current is at the cur-
rent limit. During t
rent through the switch is zero. Instead of observing the
full load current, the switch sees the equivalent load
current times duty cycle or I
t
37ms and typical t
12%, which results in an 88% power savings over the
switch being on the entire time. The duty cycle is con-
sistent across the process and devices.
When the forward or reverse current-limit threshold is
exceeded, t
resets if the overcurrent condition disappears before
t
current condition continues up to the end of the blank-
Table 1. MAX4789–MAX4794 Switch Truth Table
RETRY
BLANK
BLANK
temperature limit of +150°C.
blanking period.
Autoretry (MAX4790/MAX4792/MAX4794)
Latch Off (MAX4789/MAX4791/MAX4793)
High
High
High
Low
IN
ON
200mA/250mA/300mA Current-Limit Switches
is below UVLO threshold.
, the switch is turned on again. If the fault still
/(t
BLANK
has elapsed. The switch is shut off if the over-
BLANK
Undervoltage Lockout
BLANK
BLANK
has elapsed. A retry time delay, t
Current Limit
+ t
RETRY
_______________________________________________________________________________________
Thermal
FAULT
RETRY
timer begins counting (Figure 2).
timer begins counting. The timer
RETRY
X
, when the switch is off, the cur-
= 259ms, the duty cycle is
). With a typical t
BLANK
OFF
OFF
OFF immediately (t
OFF after t
ON during t
MAX4790, MAX4792, and MAX4794; cycle repeats until fault
is removed
SUPPLY
has elapsed and
BLANK
= I
BLANK
BLANK
LOAD
BLANK
RETRY
period has elapsed
period, OFF during t
BLANK
SWITCH ON/OFF
=
✕
,
,
period does not apply)
ing time. Reset the switch by either toggling ON (Figure
3a) or cycling the input voltage below UVLO, typically
2V (Figure 3b).
The MAX4789–MAX4794 feature 14ms (min) fault blank-
ing. Fault blanking allows current-limit faults, including
momentary short-circuit faults that occur when hot
swapping a capacitive load, and also ensures that no
fault is issued during power-up. When a load transient
causes the device to enter current limit, an internal
counter starts. If the load-transient fault persists beyond
the fault-blanking timeout, the MAX4789/MAX4791/
MAX4793 FLAG asserts low. Load-transient faults less
than t
current-limit faults are blanked.
A thermal fault and input voltage drops below the UVLO
threshold cause FLAG to assert immediately and do not
wait for the blanking time.
The MAX4789–MAX4794 have a thermal shutdown fea-
ture to protect the devices from overheating. The switch
turns off and FLAG goes low immediately (no fault blank-
ing) when the junction temperature exceeds +150°C.
The switch turns back on when the device temperature
drops approximately 15°C.
Figure 2. MAX4790/MAX4792/MAX4794 Autoretry Fault
Blanking Diagram
CURRENT
SWITCH
STATUS
LOAD
OFF
ON
BLANK
RETRY
do not cause a FLAG output assertion. Only
period for the
t
BLANK
t
RETRY
t
BLANK
SUPPLY CURRENT MODE
See the Autoretry section
Thermal Shutdown
Fault Blanking
Shutdown
Shutdown
Latch off
Latch off
t
BLANK
CURRENT
CONDITION
REMOVED
LIMIT
SHORT
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