Description
When SMCLK is used as the clock source for the ADC (ADC12CTL1.ADC12SSELx =
11) and CSCTL4.SMCLKOFF = 1, the ADC will stop operating if the ADC clock source is
changed by user software (e.g. in the ISR) from SMCLK to a different clock source. This
issue appears only for the ADC12CTL1.ADC12DIVx settings /3/5/7. The hang state can
be recovered by PUC/POR/BOR/Power cycle.
Workaround
1. Set CSCTL4.SMCLKOFF = 0 before switch ADC clock source.
OR
2. Only use ADC12CTL1.ADC12DIVx as /1, /2, /4, /6, /8
AUXPMM2
AUXPMM Module
Category
Functional
Function
Latch-up in AUXPMM
Description
Latch-up current can appear at the AUXPMM module supply pins in the following two
scenarios:
Scenario 1: When the AUXPMM is configured for hardware- or software-controlled
switching and the module switches from DVCC to AUXVCC2, latch-up current can
appear at AUXVCC2 at the switching point defined by SVSMHCTL.SVSMHRRL (or
AUXCTL2.AUX0LVLx). The probability for this event to occur depends on:
a) Operating temperature (higher temperatures increase probability)
b) External AUXVCC2 voltage level (higher voltages increase probability)
c) SVSMHRRL level (lower levels increase probability) defining the switching level in
hardware-controlled mode
d) AUX0LVLx level (lower levels increase probability) defining the switching level in
software-controlled mode (applicable to DVCC only)
Scenario 2: When a battery is connected to DVCC, AUXVCC1 or AUXVCC2 as the first
voltage supply, due to the low internal resistance of the battery a very fast rise time is
seen by the AUXPMM and latch-up current can appear at the connected supply if:
a) Rise times are in the range of 140 kV/s (faster rise times increase probability)
b) Device operates at temperatures of 75 deg C and above (higher temperatures increase
probability)
The latch-up current disappears after complete power cycles of all supply sources.
Workaround
For scenario 1:
- Increase SVSMRRL to a level above maximum external voltage expected on AUXVCC2.
SVSMRRL = 6 or 7 (requires VCORE level of 3) is applicable for AUXVCC2 of up to
maximum voltage, 3.58V, while a lower SVSMRRL setting can be selected if a lower
voltage (e.g. 3.3V) is expected on AUXVCC2.
Or
- Connect all 3 supplies via 3 external diodes to DVCC and realize the switching externally
without using the internal AUXPMM switches. See application report
Three-Phase Electronic Watt-Hour Meter Using the MSP430F471xx"
Or
- Use AUXVCC1 instead of AUXVCC2 for backup supply
Advisory Descriptions
SLAZ646S – FEBRUARY 2015 – REVISED MAY 2021
MSP430F6736A Microcontroller
7
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