JAJSSA9 November 2023 DAC61401 , DAC81401
PRODUCTION DATA
If the device output pins are exposed to industrial transient testing without external protection components, the internal diode structures of the DAC81401 become forward biased and conduct current. If the conducted current is large, as is common in high-voltage industrial transient tests, the structures become permanently damaged and impact the device functionality.
The gain-stage output and attenuation-stage input includes an external electrical-overstress protection circuit for short-circuit events. Protection is achieved by the transient voltage suppressor (TVS) diodes D3 and D6, and clamp-to-rail diodes D1, D2, D4, D5.
The combined effects of both TVS and clamp-to-rail diodes limits the current flowing into the device internal diode structures to prevent permanent damage. If the Schottky diode clamps VOUT to ±1.5 V from the rail, then the peak current entering the device is equal to 80 mA, assuming R1 = 10 Ω and the diode FB is 0.7 V. Also include TVS diodes D3 and D6 at the gain-stage output and attenuation-stage input nodes to provide a discharge path for the energy sent to these nodes through diodes D3 and D6, and the internal diode structures. In the absence of these diodes, when current is diverted to these nodes, the decoupling capacitors charge, slowly increasing the voltage at these nodes, which can exceed the threshold limits of HV+ and HV–.