Chapter 17 Gate Drive Unit (GDUV4)
MC9S12ZVM Family Reference Manual Rev. 1.3
Freescale Semiconductor
647
17.4
Functional Description
17.4.1
General
The PMF module provides the values to be driven onto the outputs of the low-side and high-side FET pre-
drivers. If the FET pre-drivers are enabled, the PMF channels drive their corresponding high-side or low-
side FET pre-drivers according
17.4.2
Low-Side FET Pre-Drivers
The three low-side FET pre-drivers turn on and off the external low-side power FETs. The energy required
to charge the gate capacitance of the power FET C
G
is drawn from the output of the voltage regulator VLS.
See
. The register bits GSRCLS[2:0] in the GDUSRC Register (see
) control the slew
Table 17-19. GDUOC1 Register Field Descriptions
Field
Description
7
GOCA1
GDU Overcurrent Action — This bit cannot be modified after GWP bit is set. This bit controls the action in
case of an overcurrent event or overvoltage event. See
6
GOCE1
GDU Overcurrent Enable — This bit cannot be modified after GWP bit is set.
0 Overcurrent Comparator 1 is disabled
1 Overcurrent Comparator 1 is enabled
3:0
GOCT1[3:0]
GDU Overcurrent Comparator Threshold — These bits cannot be modified after GWP bit is set. The
overcurrent comparator threshold voltage is the output of a 6-bit digital-to-analog converter. The upper two bits
of the digital inputs are tied to one. The other bits of the digital inputs are driven by GOCT0[3:0]. The overcurrent
comparator threshold voltage can be calculated from equation below.
Table 17-20. PMF Channel Assignment
PMF
Channel
PMF Channel Assignment
0
High-Side Gate and Source Pins HG[0], HS[0]
1
Low-Side Gate and Source Pins LG[0], LS[0]
2
High-Side Gate and Source Pins HG[1], HS[1]
3
Low-Side Gate and Source Pins LG[1], LS[1]
4
High-Side Gate and Source Pins HG[2], HS[2]
5
Low-Side Gate and Source Pins LG[2], LS[2]
Voct1
49
GOCT1
+
(
)
VDDA
64
------------------
⋅
=
