ISO808A

The ISO808A, ISO808A-1, are galvanic isolated 8-channel drivers featuring a low supply current. Each driver contains 2 independent galvanic isolated voltage domains (V_CC and V_DD for the Process and Control Logic stages, respectively). The ICs are intended for driving any kind of load with one side connected to ground.

The Control Logic Stage features an 8-bit Output Status Register (where the MCU sets the ON/OFF status of the output channels in the Process Stage), daisy chaining is allowed. The two stages communicate through the galvanic isolation channel by an ST proprietary protocol.

Active channel current limitation (OVL) combined with thermal shutdown (OVT), independent for each channel, protects the device against overload.

Built-in thermal shut down protects each channel from over-temperature and overload: each overheated channel automatically turns OFF after its junction temperature triggers the protection threshold (T_JSD). The channel turns back ON if its junction temperature decreases lower than restart threshold (T_JR).

An additional case temperature sensor protects the whole chip against over-temperature (OVC event): if the case temperature triggers the T_CSD threshold then overloaded channels are turned OFF and will restart only when case temperature decreased down to the reset threshold (T_CR). Non overloaded channels continue to operate normally.

Other embedded functions are loss of ground protection, V_CC and V_DD UVLOs (with hysteresis), watchdog and V_CC Power GOOD.

An internal circuit provides an OR-wired not latched common FAULT indicator signaling the channel OVT. The PGOOD diagnostic pin is activated if V_CC goes below the power good threshold. Both FAULT and PGOOD pins are open drain, active low, fault indication pins.