AP2152ASG-13 Diodes Zetex, AP2152ASG-13 Datasheet - Page 11

• Manufacturer Part Number: AP2152ASG-13
• Manufacturer: Diodes Zetex

Specifications of AP2152ASG-13

• Short Circuit Current Limit: 700mA
• Input Voltage Range: 2.7 to 5.5V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 8
• Lead Free Status / RoHS Status: Supplier Unconfirmed

Application Note
Power Supply Considerations
A 0.1μF to 1μF X7R or X5R ceramic bypass capacitor between IN and GND, close to the device, is
recommended. Placing a high-value electrolytic capacitor on the input and output pin(s) is recommended when
the output load is heavy. This precaution reduces power-supply transients that may cause ringing on the input.
Additionally, bypassing the output with a 1μF ceramic capacitor improves the immunity of the device to short-
circuit transients.
Over-current and Short Circuit Protection
An internal sensing FET is employed to check for over-current conditions. Unlike current-sense resistors, sense
FETs do not increase the series resistance of the current path. When an overcurrent condition is detected, the
device maintains a constant output current and reduces the output voltage accordingly. Complete shutdown
occurs only if the fault stays long enough to activate thermal limiting.
Three possible overload conditions can occur. In the first condition, the output has been shorted to GND before
the device is enabled or before V
immediately clamps output current to a certain safe level namely I
In the second condition, an output short or an overload occurs while the device is enabled. At the instance the
overload occurs, higher inrush current may flow for a very short period of time before the current limit function can
react. The input capacitor(s) rapidly discharge through the device, activating current limit circuitry. Protection is
achieved by momentarily opening the P-MOS high-side power switch and then gradually turning it on. After the
current limit function has tripped (reached the over-current trip threshold), the device switches into current limiting
mode and the current is clamped at I
In the third condition, the load has been gradually increased beyond the recommended operating current. The
current is permitted to rise until the current-limit threshold (I
exceeded. The AP2142A/AP2152A is capable of delivering current up to the current-limit threshold without
damaging the device. Once the threshold has been reached, the device switches into its current limiting mode and
is set at I
FLG Response
When an over-current or over-temperature shutdown condition is encountered, the FLG open-drain output goes
active low after a nominal 7-ms deglitch timeout. The FLG output remains low until both over-current and over-
temperature conditions are removed. Connecting a heavy capacitive load to the output of the device can cause a
momentary over-current condition, which does not trigger the FLG due to the 7-ms deglitch timeout. The
AP2142A/AP2152A is designed to eliminate false over-current reporting without the need of external components
to remove unwanted pulses.
Power Dissipation and Junction Temperature
The low on-resistance of the internal MOSFET allows the small surface-mount packages to pass large current.
Using the maximum operating ambient temperature (T
Finally, calculate the junction temperature:
Where:
AP2142A/2152A
Document number: DS32191 Rev. 2 - 2
P
T
T
R
P
D
J
A
D
θJA
= Ambient temperature °C
= P
= R
= Total power dissipation
LIMIT
= Thermal resistance
D
DS(ON)
.
x R
θJA
× I
+ T
2
A
IN
LIMIT
has been applied. The AP2142A/AP2152A senses the short circuit and
. The threshold for activating current limiting is 0.7A typical per channel.
0.5A DUAL CHANNEL CURRENT-LIMITED POWER
www.diodes.com
A
11 of 17
) and R
TRIG
) is reached or until the thermal limit of the device is
DS(ON)
LIMIT
SWITCH WITH OUTPUT DISCHARGE
, the power dissipation can be calculated by:
.
AP2142A/AP2152A
© Diodes Incorporated
October 2010