Texas Instruments DRV814x-Q1EVM, Руководство пользователя, Страница: 8 / 22

Figure 3-4. Main Supply Section
3.2.5 Current Limit Header (RIPROPI)
The DRV824x and DRV814x family of devices integrate a current sense output using current mirrors on the
low-side power MOSFETs on the IPROPI device pin. The IPROPI pin sources a small current proportional
to the current in the high side MOSFETs (current sourced out of the IPROPI pin). The IPROPI current can
be converted to a proportional voltage using an external resistor ( R
IPROPI
). The integrated current sensing
allows the DRV824x and DRV814x devices to limit the output current with a fixed off-time PWM chopping
scheme and provides load information to an external controller to detect changes in load or stall conditions.
The integrated current sensing outperforms traditional external shunt resistor sensing by providing current
information even during the off-time slow decay recirculating period. Additionally, BOM cost and PCB area is
reduced by eliminating a large external power shunt resistor. The off-time PWM current regulation level can be
configured during motor operation through the ITRIP function to limit the load current accordingly to the system
demands.
Selecting the R
IPROPI
value must be done in conjunction with the ITRIP level (configured through SPI or external
jumper selection depending on SPI or hardware device variant) and is governed by the following relationship:
ITRIP (AMPS) = V
ITRIP_LVL
/R
IPROPI
* A
IPROPI
(1)
Example (Typical values from DRV8245-Q1 datasheet; A
IPROPI
will vary by part number):
Refer to the Electrical Characteristics CURRENT SENSE AND REGULATION table in device datasheet for
R
IPROPI
values matching the output capability of the device installed on your EVM.
Figure 3-5 shows the header with user selectable R
IPROPI
values.
Evaluation Hardware Overview www.ti.com
8 DRV824x_DRV814x-Q1EVM User’s Guide SLVUC46A – MARCH 2021 – REVISED JULY 2021
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