Rainbow Electronics MAXQ7670 - Manual (Page 21)

MAXQ7670
Microcontroller with 10-Bit ADC,
PGA, 64KB Flash, and CAN Interface
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The DVDD reset supervisor resets the MAXQ7670 when
the +2.5V DVDD falls below the reset threshold. The
processor remains in reset until DVDD returns above
the reset threshold. The µC does not execute com-
mands in reset mode. See Figure 6 for the µC response
to DVDD brownout and reset.
Refer to the MAXQ7670 User’s Guide for detailed pro-
gramming information, and a more thorough descrip-
tion of POR and brownout behavior.
Internal 3.3V Linear Regulator
The integrated 3.3V 50mA linear regulator or an exter-
nal 3.3V supply powers AVDD. The integrated 3.3V reg-
ulator is inactive upon power-up. Enable the integrated
regulator with software programming after power-up.
When using an external supply, connect a regulated
3.3V supply to AVDD after applying DVDDIO.
Internal 2.5V Linear Regulator
The integrated 2.5V 50mA linear regulator or an exter-
nal 2.5V supply applied at DVDD powers DVDD.
Connect REGEN2 to GNDIO to enable the integrated
regulator. Connect REGEN2 to DVDDIO to use an
external supply. When using an external supply, con-
nect a regulated 2.5V supply to DVDD after applying
DVDDIO.
DVDDIO Current Requirements
Both internal linear regulators are capable of supplying
up to 50mA each. When using the regulators to power
AVDD and DVDD and to provide power to external
devices, make sure DVDDIO’s power input can source
a current greater than the sum of the MAXQ7670 sup-
ply current and the load currents of the two regulators.
DGND
NOMINAL
DVDD (+2.5V)
BROWNOUT
RESET
(BOR)
+2.38V
INTERNAL RESET
BOR STATE
RESET OUTPUT
+2.25V
BROWNOUT
INTERRUPT
(BOI)
DVLVL FLAG
(ASR[14])
DVBI FLAG
(ASR[4])
FLAG ARBITRARILY
CLEARED BY
µC
VDBE BIT SET BY µC
DVDD BROWNOUT
INTERRUPT
THRESHOLD RANGE
Figure 6. DVDD Brownout and Reset Behavior