Datasheet

14 Maxim Integrated
16-Bit Microcontrollers with
Infrared Module and Optional USB
MAXQ612/MAXQ622
Pin Descriptions—TQFN, LQFP (continued)
PIN
NAME FUNCTION
MAXQ612
TQFN-EP
MAXQ612
LQFP
MAXQ622
LQFP
RESET PINS
12 15 15
RESET
Digital, Active-Low, Reset Input/Output. The CPU is held in reset when this
pin is low and begins executing from the reset vector when released. The
pin includes pullup current source and should be driven by an open-drain,
external source capable of sinking in excess of 4mA. This pin is driven low
as an output when an internal reset condition occurs.
CLOCK PINS
16 25 25 HFXIN
High-Frequency Crystal Input. Connect an external crystal or resona-
tor between HFXIN and HFXOUT as the high-frequency system clock.
Alternatively, HFXIN is the input for an external, high-frequency clock
source when HFXOUT is shorted to ground during POR.
17 26 26 HFXOUT
USB FUNCTION PINS
— — 19 V
BUS
USB V
BUS
Supply Voltage. Connect V
BUS
to a positive 5.0V power sup-
ply. Bypass V
BUS
to ground with a 1.0FF ceramic capacitor as close to
the V
BUS
pin as possible.
— — 16 DP
USB D+ Signal. This bidirectional pin carries the positive differential
data or single-ended data. Connect this pin to a USB “B” connector.
This pin is weakly pulled high internally when the USB is disabled.
— — 18 DM
USB D- Signal. This bidirectional pin carries the negative differential
data or single-ended data. Connect this pin to a USB “B” connector.
This pin is weakly pulled high internally when the USB is disabled.
— — 20 V
DDB
USB Transceiver Supply Voltage. This is the power output of the internal
voltage regulator that is used for the USB transceiver (3.3V) block. This
pin is bypassed to ground with a 1.0FF capacitor as close as possible
to the package. No external circuitry should be powered from this pin.
— — 21 V
DDIO
Switched 3V Power Supply. This is the power output after selection
between V
BUS
and V
DD
. Must be connected to an external ceramic
chip capacitor. The capacitor must be placed as close to this pin as
possible. No external devices other than the capacitor should be con-
nected to this pin.
IR FUNCTION PINS
42 64 64 IRTX
IR Transmit Output. Active-low IR transmit pin capable of sinking 25mA.
This pin defaults to three-state input with the weak pullup disabled dur-
ing all forms of reset. Software must configure this pin after release from
reset to remove the three-state input condition.
43 1 1 IRRX IR Receive Input