SBASAD0A March 2022 – July 2022 AMC23C10
PRODUCTION DATA
The open-drain output powers up in a high-impedance (Hi-Z) state when the low-side supply (VDD2) turns on. After power-up, if the high-side is not functional yet, the output is actively pulled low. This condition happens after the low-side start-up time plus the high-side fault detection delay time (tLS,STA + tHS,FLT), as shown in Figure 7-3. Similarly, if the high-side supply drops below its undervoltage threshold (VDD1UV) for more than the high-side fault detection delay time during normal operation, the open-drain output is pulled low, as shown in Figure 7-6. This delay allows the system to shut down reliably when the high-side supply is missing.
The push-pull output (OUT2) of the AMC23C10 behaves similarly to the open-drain output (OUT1) but with reverse polarity.
Communication starts between the high-side and low-side of the comparator is delayed by the high-side blanking time (tHS,BLK, a time constant implemented on the high-voltage side) to avoid unintentional switching of the comparator output during power-up.
Figure 7-3 through Figure 7-8 depict typical power-up and power-down scenarios.
In Figure 7-3, the low-side supply (VDD2) turns on but the high-side supply (VDD1) remains off. OUT1 powers up in a Hi-Z state, and OUT2 is low. After tHS, FLT, OUT1 is driven low and OUT2 is driven high, indicating a no-power fault on the high-side.
In Figure 7-4, the high-side supply (VDD1) turns on long after the low-side supply (VDD2) turns on. OUT1 is initially in a low state and OUT2 is in a high state, see case (1). After the high-side supply is enabled, there is a duration of tHS,STA + tHS, BLK before the device assumes normal operation and the outputs reflect the current state of the comparator.
In Figure 7-5, the low-side supply (VDD2) turns on, followed by the high-side supply (VDD1) with only a short delay. OUT1 is initially in a Hi-Z state, and OUT2 is low. The high-side fault detection delay (tHS,FLT) is shorter than the high-side blanking time (tHS,BLK), and therefore OUT1 is driven low and OUT2 is driven high after tHS,FLT, indicating that the high-side is not operational yet. After the high-side blanking time (tHS,BLK) elapses, the device assumes normal operation and the outputs reflect the current state of the comparator.
In Figure 7-6, the high-side supply (VDD1) turns off, followed by the low-side supply (VDD2). After the high-side fault detection delay time (tHS,FLT), OUT1 is driven low and OUT2 is driven high. As soon as VDD2 drops below the VDD2UV threshold, OUT1 enters a Hi-Z state and OUT2 is driven low.
In Figure 7-7, the low-side supply (VDD2) turns on after the high-side is fully powered up (the delay between VDD1 and VDD2 is greater than (tHS,STA + tHS,BLK)). OUT1 starts in a Hi-Z state and OUT2 starts in a low state. After the low-side start-up time (tLS,STA), the device enters normal operation.
In Figure 7-8, the low-side supply (VDD2) turns off, followed by the high-side supply (VDD1). As soon as VDD2 drops below the VDD2UV threshold, OUT1 enters a Hi-Z state and OUT2 is driven low.