Maxim-integrated MAXQ7666 Manual de usuario Pagina 75

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SECTION 2: POWER-SUPPLY/SUPERVISORY MONITORING MODULE
The MAXQ7665/MAXQ7666 power-supply/supervisory monitoring module supports dedicated supply pins to independently power analog,
digital I/O, and digital core functions. The analog functions and digital I/O are powered from an external +5V supply, while the internal digi-
tal core is powered from a +3.3V supply, which can be supplied by an on-chip linear regulator. Except where explicitly noted, the MAXQ7665
and MAXQ7666 support identical features.
The MAXQ7665/MAXQ7666 power-supply/supervisory monitoring module features include the following.
Dedicated analog supply (+5.0V) and ground pins
Dedicated digital I/O supply (+5.0V) and ground pins
Dedicated digital core supply (+3.3V) and ground pins
On-chip +3.3V linear regulator
Digital core brownout interrupt and reset voltage monitors
Digital I/O brownout voltage monitor (can also be used to monitor analog supply)
User-programmable thresholds for digital core brownout reset and interrupt generation
User-programmable thresholds for digital I/O brownout interrupt generation
Five reset sources: power-on, brownout, external, WDT, and internal system
2.1 Architecture
Figure 2-1 shows a simplified functional block diagram of the MAXQ7665/MAXQ7666 power-supply/supervisory monitoring module.
The MAXQ7665/MAXQ7666 microcontrollers are +5V-powered devices. Three power supplies are used to operate the various mod-
ules in the microcontroller. The MAXQ7665/MAXQ7666’s digital I/O supply (DVDDIO) uses two +5.0V supply pins to power the digital
I/Os. An internal +3.3V linear regulator powers the digital core functions composed of internal CPU, memory, oscillator, and digital
peripherals. If required, an external +3.3V supply (DVDD) can instead be used by disabling (REGEN pin connected to DVDDIO) the
internal regulator. The analog module uses a separate power-supply line (AVDD) to allow additional filtering to maintain superior ana-
log performance.
The MAXQ7665/MAXQ7666 contain two brownout power-supply monitors. One power-supply monitor is dedicated to the DVDDIO for
brownouts, while the other monitors brownouts of the DVDD core supply of the microcontroller, and can actually cause a reset if DVDD
is too low. The AVDD supply can be connected to the DVDDIO supply lines, and can then also be monitored by the DVDDIO monitor.
The power-on reset circuit is integrated into the DVDD power-supply monitor and the default trip level is between 2.7V and 2.99V. T h e
DVDDIO and DVDD brownout detection thresholds are user selectable, and can be configured independently to interrupt the micro-
controller when either of the selected thresholds are crossed.
MAXQ7665/MAXQ7666 Users Guide
2-3
Maxim Integrated
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