EM78468AQ EMC [ELAN Microelectronics Corp], EM78468AQ Datasheet - Page 53

• Manufacturer Part Number: EM78468AQ
• Description: 8-BIT Microcontroller
• Manufacturer: EMC [ELAN Microelectronics Corp]

Product Specification (V1.1) 04.11.2005
(This specification is subject to change without further notice)
8 bit dow n counter
A uto-reload buf f er
Pre-scaler
Fs
Counter 2
(IOCC0)
(IOC91)
Fig. 22: LGP=0, HF=1, the IROUT waveform can modulate Fcarrier waveform when in
low-pulse width time.
Fig. 23 : LGP=0, HF=0, the IROUT waveform cannot modulate Fcarrier waveform when
in low-pulse width time. So IROUT waveform is determined by high-pulse time and
low-pulse time. This mode can produce standard PWM waveform
Fig. 24 : LGP=0, HF=1, the IROUT waveform can modulate Fcarrier waveform when in
low-pulse width time. When IRE goes from high to low, the output waveform of IROUT
will keep on transmitting till high-pulse width timer interrupt occurs.
Fig. 25: LGP=0, HF=0, the IROUT waveform can not modulate Fcarrier waveform when
in low-pulse width time. So IROUT waveform is determined by high-pulse time and
low-pulse time. This mode can produce standard PWM waveform. When IRE goes from
high to low, the output waveform of IROUT will keep on transmitting till high-pulse width
timer interrupt occurs.
Fig.26 : LGP=1, when this bit is set to high level, the high-pulse width timer is ignored. So
IROUT waveform output from low-pulse width timer is established.
The IROUT output waveform is further explained in the following figures:
Fm
8
8
Pre-sc aler
Fm: main oscillator frequency ; Fs: sub-oscillator frequency
(IOC A 1)
Fcarrier
Fig. 21 IR/PWM System Block Diagram
HF
RE register
High-Puls e Width Timer
8 bit dow n counter
A uto-reload buf f er
LGP
(IOCD0)
H/W Modulator Circuit
IRE
8
8
8
Low -Pulse Width Timer
8 bit dow n counter
A uto-reload buf f er
( IOCE0)
Pre-s caler
(IOCA 1)
8
8
8
8-BIT Microcontroller
IROUT pin
EM78468
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