MAXQ3180 Maxim, MAXQ3180 Datasheet - Page 17

• Manufacturer Part Number: MAXQ3180
• Description: The MAXQ3180 is a dedicated electricity measurement front-end that collects and calculates polyphase voltage, current, power, energy, and many other metering and power-quality parameters of a polyphase load
• Manufacturer: Maxim

to 0, meaning that the MAXQ3180 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 MAXQ3180 is first powered up, or when the
power supply, V
trip point (outside of Stop Mode), the MAXQ3180 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
STOP MODE
POR
Low-Power, Multifunction, Polyphase AFE
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
MAXQ3180 to reset in the same way.
The MAXQ3180 includes a hardware watchdog timer that
is armed and periodically reset automatically during nor-
mal operation. Under normal circumstances, the
MAXQ3180 always resets the watchdog timer often
enough to prevent it from expiring. However, if an internal
error of some kind causes the MAXQ3180 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 watch-
dog 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 MAXQ3180 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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