AP2553W6-7 Diodes Inc., AP2553W6-7 Datasheet - Page 10

• Manufacturer Part Number: AP2553W6-7
• Description: Power Switch ICs - USB 2.1A Precision ADJ 5.5V 2.1A 210kOhm
• Manufacturer: Diodes Inc.

Specifications of AP2553W6-7

• Rohs: yes
• Supply Voltage - Min: 2.7 V
• Supply Voltage - Max: 5.5 V
• Maximum Operating Temperature: + 150 C
• Minimum Operating Temperature: - 40 C
• Package / Case: SOT26
• Mounting Style: SMD/SMT
• Number Of Switches: Single
• Off Time (max): 0.5 ms
• On Resistance (max): 70 mOhms
• On Time (max): 1.5 ms
• Operating Temperature Range: - 40 C to + 150 C
• Supply Current: 2.1 A
• Switch Configuration: Single

Application Note
Current-Limit Threshold Programming
Best fit Current-Limit Threshold Equations (I
Thermal Protection
Thermal protection prevents the IC from damage when the die temperature exceeds safe margins. This mainly occurs when heavy-overload or
short-circuit faults are present for extended periods of time. The AP2552/53 AND AP2552A/53A implements a thermal sensing to monitor the
operating junction temperature of the power distribution switch. Once the die temperature rises to approximately +160°C (140°C in case the part
is under current limit), the thermal protection feature gets activated as follows: The internal thermal sense circuitry turns the power switch off and
the FAULT output is asserted thus preventing the power switch from damage. Hysteresis in the thermal sense circuit allows the device to cool
down by approximately +20°C before the output is turned back on. This built-in thermal hysteresis feature is an excellent feature, as it avoids
undesirable oscillations of the thermal protection circuit. The switch continues to cycle in this manner until the load fault is removed, resulting in
a pulsed output.
Reverse-Current and Reverse-Voltage Protection
The USB specification does not allow an output device to source current back into the USB port. In a normal MOSFET switch, current will flow in
reverse direction (from the output side to the input side) when the output side voltage is higher than the input side. A reverse-current limit
(ROCP) feature is implemented in the AP2552/53 AND AP2552A/53A to limit such back currents. The ROCP circuit is activated when the output
voltage is higher than the input voltage. After the reverse current circuit has tripped (reached the reverse current trip threshold), the current is
clamped at this IROCP level.
In addition to ROCP, reverse over-voltage protection ( ROVP ) is also implemented. The ROVP circuit is activated by the reverse voltage
comparator trip point ie; the difference between the output voltage and the input voltage.
For AP2552/53, once ROVP is activated, FAULT assertion occurs at a de-glitch time of 4ms. Recovery from ROVP is automatic when the fault is
removed. FAULT de-assertion de-glitch time is same as the de-assertion time.
AP2552/AP2553/AP2552A/AP2553A
Document number: DS35404 Rev. 6 - 2
I
LIM
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MAX
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(
A
)

R
LIM
20
(cont.)
. 0
.
904
08
k

LIMIT
(cont.)
):
Figure 15 Current-Limit Threshold vs. R
I
LIM
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TYP
www.diodes.com
)
(
mA
10 of 16
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
R
LIM
19
. 0
.
94
925
AP2552/ AP2553/ AP2552A/ AP2553A
k

LIM
I
LIM
(
MIN
)
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mA
)

R
LIM
20
. 0
© Diodes Incorporated
.
956
26
k

April 2013