MAXQ613 Maxim, MAXQ613 Datasheet - Page 14

• Manufacturer Part Number: MAXQ613
• Description: The MAXQ613 is a low-power, 16-bit MAXQ® microcontroller designed for low-power applications including universal remote controls, consumer electronics, and white goods
• Manufacturer: Maxim

16-Bit Microcontroller with Infrared Module
The IRCAH byte defines the carrier high time in terms of
the number of IR input clocks, whereas the IRCAL byte
defines the carrier low time.
• IR Input Clock (f
• Carrier Frequency (f
• Carrier High Time = IRCAH + 1
• Carrier Low Time = IRCAL + 1
• Carrier Duty Cycle = (IRCAH + 1)/(IRCAH + IRCAL + 2)
During transmission, the IRCA register is latched for
each IRV down-count interval, and is sampled along with
the IRTXPOL and IRDATA bits at the beginning of each
new IRV down-count interval so that duty-cycle variation
and frequency shifting is possible from one interval to the
next, which is illustrated in Figure 1.
Figure 1. IR Transmit Frequency Shifting Example (IRCFME = 0)
14
IRCAL + 2)
CARRIER OUTPUT
_____________________________________________________________________________________
IR INTERRUPT
IRTXPOL = 1
IRTXPOL = 0
IRDATA
IRMT
IRCA
(IRV)
IRTX
IRTX
IRCLK
0
Carrier Generation Module
IRCA = 0202h
IRMT = 3
) = f
CARRIER
1
SYS
/2
) = f
IRDIV[1:0]
IRCLK
3
/(IRCAH +
2
1
IRCA = 0002h
IRMT = 5
0
IRCA, IRMT, IRDATA SAMPLED AT END OF IRV
DOWN-COUNT INTERVAL
Figure 2 illustrates the basic carrier generation and its
path to the IRTX output pin. The IR transmit polarity bit
(IRTXPOL) defines the starting/idle state and the carrier
polarity of the IRTX pin when the IR timer is enabled.
During IR transmission (IRMODE = 1), the carrier gen-
erator creates the appropriate carrier waveform, while
the carrier modulator performs the modulation. The car-
rier modulation can be performed as a function of carrier
cycles or IRCLK cycles dependent on the setting of the
IRCFME bit. When IRCFME = 0, the IRV down counter is
clocked by the carrier frequency and thus the modula-
tion is a function of carrier cycles. When IRCFME = 1, the
IRV down counter is clocked by IRCLK, allowing carrier
modulation timing with IRCLK resolution.
The IRTXPOL bit defines the starting/idle state as well as
the carrier polarity for the IRTX pin. If IRTXPOL = 1, the
5
4
0
3
2
1
0
IR Transmission