MAXQ3181 Maxim, MAXQ3181 Datasheet - Page 15

• Manufacturer Part Number: MAXQ3181
• Description: The MAXQ3181 is a dedicated electricity measurement front-end that collects and calculates polyphase voltage, current, active power and energy, and many other metering parameters of a polyphase load
• Manufacturer: Maxim

to 0, meaning that the MAXQ3181 always switches to
the high-frequency clock before it begins accepting
commands in Initialization Mode.
When an external reset occurs from Stop Mode, execu-
tion (in Initialization Mode) resumes after 128 cycles of
the internal RC oscillator (or approximately 128μs).
When the MAXQ3181 is first powered up, or when the
power supply, V
trip point (outside of Stop Mode), the MAXQ3181 is
held in power-on reset. Once the power supply rises
above the V
released and all registers are reset to their defaults and
execution resumes in Initialization Mode. The high-fre-
quency external crystal (LOWPM = 0) is always select-
ed as the clock source following any power-on or
brownout reset.
In Stop Mode brownout detection is disabled, so a
power-on reset does not occur until V
lower level (V
Figure 2. Brownout Reset
RST
Low-Power, Active Energy, Polyphase AFE
STOP MODE
POR
INTERNAL
DVDD
______________________________________________________________________________________
RESET
level, the power-on reset state is
V
). From the master’s perspective,
V
RST1
POR
, drops below the V
t
POR
ENABLED OUTSIDE OF STOP MODE)
BROWNOUT DETECTION (ALWAYS
FORCES RESET STATE. POR = 1
Power-On Reset
DVDD
RST
drops to a
power-fail
BROWNOUT DETECTION
power-on resets and brownout resets both cause the
MAXQ3181 to reset in the same way.
The MAXQ3181 includes a hardware watchdog timer
that is armed and periodically reset automatically dur-
ing normal operation. Under normal circumstances, the
MAXQ3181 always resets the watchdog timer often
enough to prevent it from expiring. However, if an inter-
nal error of some kind causes the MAXQ3181 to lock up
or enter an endless execution loop, the watchdog timer
expires and triggers an automatic hardware reset.
There is no register flag to indicate to the master that a
watchdog reset has occurred, but the RESET line
strobes low briefly.
The watchdog timer does not run during Stop Mode.
The master initiates a software reset by setting the
SWRES (OPMODE0.3) bit to 1. When a software reset
occurs, the MAXQ3181 clears all registers to their
default states and returns to Initialization Mode, in the
BROWNOUT DETECTION DISABLED.
BROWNOUT DETECTION DISABLED
POR LEVEL CAUSES RESET.
NO RESET IS GENERATED.
DURING STOP MODE.
Watchdog Reset
Software Reset
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