TC7109 View Datasheet(PDF) - Microchip Technology
Part Name
Description
MFG CO.
'TC7109' PDF : 30 Pages View PDF
TC7109/A
24 22
OSC OSC
SEL IN
23
OSC
OUT
R
C
V+ or Open FOSC = 0.45/RC
25
Buffered
OSC OUT
FIGURE 3-5:
TC7109A RC Oscillator
With OSCILLATOR SELECT input LOW, two on-chip
capacitors and a feedback device are added to the
oscillator. In this configuration, the oscillator will oper-
ate with most crystals in the 1MHz to 5MHz range, with
no external components (Figure ). The OSCILLATOR
SELECT input LOW inserts a fixed 458 divider circuit
between the BUFFERED OSCILLATOR OUTPUT and
the internal clock. A 3.58MHz TV crystal gives a
division ratio, providing an integration time given by:
EQUATION 3-1:
58
t = (2048 clock periods)
= 33.18 msec
3.58 MHz
V+
Clock
24 22
OSC OSC
SEL IN
23
OSC
OUT
GND
Crystal
÷ 58
25
Buffered
OSC OUT
FIGURE 3-6:
Crystal Oscillator
The error is less than 1% from two 60Hz periods, or
33.33msec, which will give better than 40dB, 60Hz
rejection. The converter will operate reliably at conver-
sion rates up to 30 per second, corresponding to a
clock frequency of 245.8kHz.
When the oscillator is to be over driven, the OSCILLA-
TOR OUTPUT should be left open, and the over driving
signal should be applied at the OSCILLATOR INPUT.
The internal clock will be of the same duty cycle, fre-
quency and phase as the input signal. When the
OSCILLATOR SELECT is at GND, the clock will be
1/58 of the input frequency.
Integrator Output
Zero Crossing Occurs
Zero Crossing Detected
Internal Clock
Internal Latch
Status Output
Mode Input
UART
Internal Mode Norm
Send Input
CE/LOAD
HBEN
High Byte Data
LBEN
Low Byte Data
Send Sensed
Send Sensed
Data Valid
Mode High Activates
CE/LOAD, HBEN, LBEN
Data Invalid
Terminates
UART Mode
Mode Low, not
in Handshake Mode
Disables Outputs
CE/LOAD,
HBEN,
LBEN
= Don't Care
=
Three-State
High-Impendance
=
Three-State
will Pull-up
FIGURE 3-7:
TC7109A Handshake with Send Input Held Positive
© 2006 Microchip Technology Inc.
DS21456C-page 13
Share Link: 
