Figure 4. Example schematic of SMPS external components
3.3.4 External supply mode
If there is a stable 1.25 V regulated supply available to provide the digital low voltage, the internal voltage regulator can be
disabled. This also negates the need for the external SMPS circuit. An overview of the power connections required for such a
configuration is shown in
. This is the default and only configuration for the S32R372 141MAPBGA packaged
device, due to the reduced pin count.
DC-DC
VReg
Board supply 5V -12V
SAR ADC
3.
3V
lo
w
n
ois
e
POR
Lin.
VReg
3.
3V
lo
w
n
oi
se
Lin.
VReg
Lin.
VReg
P
O
R
_B
DC-DC
VReg
AFE
Internal Lin. VRegs
3.
3V
lo
w
n
ois
e
HV_PMU
3.3V
HV_RE
G_3V8
HV_ADCREF0/2
HV_ADC
1.25V
HV_D
A
C
HV_RA
W
DC-DC
VReg
HV_FLA
HV_IOx
LV_CORE
1.25V, 1.8A
HV_IO_PWM
External
Monitor
Figure 5. Supply connections
This mode of operation can be selected by driving the VREG_SEL pin low.
This disables the internal:
• Voltage regulator (VREG)
• VDD_LV POR function (can be enabled by software)
• VDD_LV LVD/HVD circuits (can be enabled by software)
8. Not required on S32R372 141MAPBGA package as VREG_SEL is internally bonded to GND
Power supply
S32R27/37 Hardware Design Guide, Rev. 1, 04/2018
NXP Semiconductors
11