ALM2403-Q1
ZHCSMT3A –NOVEMBER 2020 –REVISED MARCH 2023
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7.3.5 Reverse Body Diodes in Output-Stage Transistors
Designed as a high-voltage, high current operational amplifier, the ALM2403-Q1 delivers robust output drive
capability. A class AB output stage with common-source transistors is used to achieve full rail-to-rail output swing
capability. Different load conditions change the ability of the amplifier to swing close to the rails.
Each output transistor has internal reverse diodes between drain and source that conduct if the output is forced
to greater than the supply or less than ground (reverse current flow). These diodes can be used as flyback
protection in inductive-load-driving applications. Limit the use of these diodes to pulsed operation in order to
minimize junction temperature overheating due to (VF × IF). Internal current-limiting circuitry does not operate
when current is flown in the reverse direction and the reverse diodes are active. A method to protect these
reverse body diodes is shown in 节8.2.2.1.2.
7.3.6 EMI Filtering
Op amps vary with regard to the susceptibility of the device to electromagnetic interference (EMI). If conducted
EMI enters the op amp, the dc offset observed at the amplifier output may shift from the nominal value while EMI
is present. This shift is a result of signal rectification associated with the internal semiconductor junctions. While
all op-amp pin functions can be affected by EMI, the signal input pins are likely to be the most susceptible. The
ALM2403-Q1 incorporates an internal input low-pass filter that reduces the amplifiers response to EMI. Both
common-mode and differential mode filtering are provided by this filter.
Texas Instruments has developed the ability to accurately measure and quantify the immunity of an operational
amplifier over a broad frequency spectrum extending from 10 MHz to 990 MHz. The EMI rejection ratio (EMIRR)
metric allows op amps to be directly compared by the EMI immunity. Detailed information can also be found in
the EMI Rejection Ratio of Operational Amplifiers application report, available for download from www.ti.com.
7.4 Device Functional Modes
7.4.1 Open-Loop and Closed-Loop Operation
As a result of the very-high, open-loop dc gain of the ALM2403-Q1, the device functions as a comparator in
open loop for most applications. A majority of electrical characteristics are verified in negative feedback, closed-
loop configurations. Certain dc electrical characteristics, like offset, may have a higher drift across temperature
and lifetime when continuously operated in open loop over the lifetime of the device.
7.4.2 Shutdown
When the OTF/SH_DN pin is left floating or is grounded, the op amp shuts down to a low IQ state and does not
operate; the op amp outputs go to a high-impedance state.
表7-1. Shutdown Truth Table
PIN NAME
LOGIC STATE
High ( > VIH_OTF )
Low ( < VIL_OTF )
OP AMP STATE
Operating
OTF/SH_DN
Shutdown (low IQ state)
Copyright © 2023 Texas Instruments Incorporated
English Data Sheet: SBOSA37
14
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