ALM2403-Q1
ZHCSMT3A –NOVEMBER 2020 –REVISED MARCH 2023
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7.3 Feature Description
7.3.1 Overtemperature and Shutdown Pin (OTF/SH_DN)
The overtemperature and shutdown pin, OTF/SH_DN, is bidirectional and allows both op amps to be put into a
low IQ state (approximately 200 µA per amplifier) when forced low or to less than VIL_OTF. As a result of being
bidirectional, and the respective enable and disable functionality, this pin must be pulled high or greater than
VIH_OTF through a pullup resistor. The use of a 10-kΩ pullup resistor leads to a drive current of approximately
210 µA when used with a pullup voltage of 3.3 V.
When the junction temperature of the ALM2403-Q1 exceeds the specified limits, OTF/SH_DN goes low to alert
the application that both the outputs have turned off because of an overtemperature event.
When OTF/SH_DN is pulled low and the op amps are shut down, the op amps are in an open loop, even when
there is negative feedback applied. This occurrence is due to the loss of the open-loop gain in the op amps when
the biasing is disabled.
7.3.2 Thermal Shutdown
If the die temperature exceeds safe limits, all outputs are disabled, and the OTF/SH_DN pin is driven low. After
the die temperature has fallen to a safe level, operation automatically resumes. The OTF/SH_DN pin is released
after operation has resumed.
When operating the die at a high temperature, the op amp toggles on and off between the thermal shutdown
hysteresis. In this event, the safe limits for the die temperature must be taken in to account. Do not continuously
operate the device in thermal hysteresis for long periods of time.
7.3.3 Current-Limit and Short-Circuit Protection
Each op amp in the ALM2403-Q1 has separate internal current limiting for the PMOS (high-side) and NMOS
(low-side) output transistors. If the output is shorted to ground, then the PMOS (high-side) current limit is
activated, and limits the current to 500 mA nominally. If the output is shorted to supply, then the NMOS (low-side)
current limit is activated and limits the current to 400 mA nominally at 25°C. The current limit value is inversely
proportional to temperature; therefore, the current limit value increases at low temperatures.
When current is limited, the safe limits for the die temperature must be taken in to account. With too much power
dissipation, the die temperature can surpass thermal shutdown limits; the op amp shuts down and reactivates
after the die has fallen below thermal limits.
CAUTION
Do not continuously operate the device in thermal hysteresis for long periods of time because this
action may cause irreversible damage to the device.
7.3.4 Input Common-Mode Range
The input common-mode range of the ALM2403-Q1 is between (V–) – 0.2 V and (V+) + 0.2 V. Staying within
this range allows the op amps to perform and operate within specification. Operating beyond these limits can
cause distortion and nonlinearities.
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Product Folder Links: ALM2403-Q1
English Data Sheet: SBOSA37
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