JAJSQR0A July 2023 – December 2023 TMCS1123
PRODUCTION DATA
In addition to a fast precision analog signal response, the TMCS1123 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 from excessive current flow caused by short circuits, motor stalls, or other system conditions. This fast digital response can be configured on both bidirectional and unidirectional devices to trip anywhere between half and over twice 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 control-loop dynamic range.
The desired overcurrent threshold IOC is set by applying an external voltage VOC to the VOC pin according to Equation 21.
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 8-5. For example, to set the desired overcurrent threshold to IOC = ±50A on the bidirectional TMCS1123A3A or TMCS1123B3A devices, or to IOC = 50A on the unidirectional TMCS1123C3A device, size the resistors R1 and R2 to apply a voltage VOC = 1.5V to the VOC pin according to Equation 21.
with
Figure 8-6 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.