SBOSAF3 November 2023 TMCS1126
ADVANCE INFORMATION
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In addition to a fast precision analog signal response, the TMCS1126 also offers a fast digital overcurrent response. The Overcurrent Detection (OCD) circuit provides a comparator output that can be used to trigger a warning or system shutdown to prevent damage that may occur in the event of excessive current flow caused by shorts circuits, motor stalls, or other system conditions. This fast digital response can be configured on both bidirectional and unidirectional devices to trip either inside or outside the analog measurement range. When set up to trigger outside the analog measurement range, this fast digital overcurrent output OC along with the precision analog output VOUT allows the user to optimize of control-loop dynamic range.
The desired overcurrent threshold IOC is set by applying an external voltage VOC to the VOC pin according to Equation 20.
where
A digital-to-analog converter (DAC) can be used to set the desired overcurrent threshold IOC, or a simple external resistor divider circuit can be used as shown in Figure 8-2. For example, to set the desired overcurrent threshold to IOC = ±50 A on the bidirectional TMCS1126A3A or TMCS1126B3A devices, or to IOC = 50 A on the unidirectional TMCS1126C3A device, resistors R1 and R2 should be sized to apply a voltage VOC = 1.5 V to the VOC pin according to Equation 20.
with
Figure 8-3 shows the overcurrent digital output OC response as active-low. When the input current exceeds ±IOC on a bidirectional device, the fast OC pin is pulled low. The input current must return to within ±IOC by more than a hysteresis current IHys before the OC pin resets back to the normal high-state.