TQ MBa8Xx, User Manual

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User's Manual l MBa8Xx UM 0100 l © 2020, TQ-Systems GmbH Page 46
3.10.2 Power sequencing (continued)
V_24V
V_12V
V_3V3
V_3V3_MB
V_1V1_USB
V_1V8 (optional)
V_5V / V_5V_CAN
V_5V_USB
V_3V3_MPCIE
V_1V5_MPCIE
V_2V5_ETH
V_1V0_ETH
V_1V2_DP
V_1V8_OUT
(from TQMa8Xx)
A B D1 D2 D3
RESET_OUT#
(from TQMa8Xx)
C
Software
dependent
Figure 24: Power-Sequencing
The following table shows the sequence steps from Figure 24:
Table 50: Power-Sequencing
Sequence Description
A Start point: Power-up MBa8Xx supplies.
B Release MBa8Xx supplies by V_1V8_OUT.
C Release RESET_OUT# after completion of TQMa8Xx power sequencing plus preconfigured delay.
D1, D2, D3
Switching on of additional supply by software driver with signals
V_3V3_MPCIE_EN, V_1V5_MPCIE_EN and V_12V_EN.
V_1V8_OUT controls the regulators for V_5V and V_1V8, as well as the power FET for V_3V3_MB. Thus the linear regulators for
V_2V5_ETH, V_1V0_ETH, V_1V2_DP and V_1V1_USB as well as the DC/DC regulator for V_5V_CAN are activated automatically.
Determined by the internal power sequence of the TQMa8Xx, RESET_OUT# is only released with a corresponding time offset
after the last voltage level V_1V8_OUT (TQMa8Xx internal V_1V8) is switched on. Thus all necessary voltages on the TQMa8Xx
and the carrier board are stable when the system starts.
The 1.8 V supply for the components on the MBa8Xx is provided by default via pin X2-12 (V_1V8_OUT) of the TQMa8Xx.
Alternatively, a 1.8 V voltage regulator can be used on the MBa8Xx via a mounting option. The following table shows the
corresponding options.
Table 51: Assembly option 1.8 V regulator
1.8 V Supply R182 R364 Remark
TQMa8Xx (V_1V8_OUT) NP 0 Ω Default
Voltage regulator on the MBa8Xx (LM25119) 0 Ω NP –