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TELCOM SEMICONDUCTOR, INC.
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5V PRECISION DATA ACQUISITION
SUBSYSTEMS
TC530
TC534
verter input. A0 is the least significant address bit (i.e.,
channel 1 is selected when A0 = 1 and A1 = 0). The
multiplexer is designed to be operated in a differential mode.
For single-ended inputs, the CHx
–
input for the channel
under selection must be connected to the ground reference
associated with the input signal.
EOC
R/W
RESET
D
CLK
D
IN
1
MSB
1
0
0
1
1
1
1
AZ
AZ
LOAD VALUE
LSB
INT
DINT
IZ
AZ…
Conversion
Phase
Timing
Status
Converter held in AZ
state due to RESET = 1
Write LOAD VALUE to Serial Port
Power-up RESET
Undefined
Converter in Normal Service
R/W brought LOW during AZ
for serial port write cycle
R/W = HIGH strobes
LOAD VALUE into
timebase and starts
conversion
Continuous Conversions
Figure 4. TC530/534 Initialization and Load Value Write Cycle
EOC
OVR POL MSB
LSB
R/W
D
CLK
D
OUT
Figure 5. Serial Port Data Read Cycle
DC/DC Converter
An on-board, TC7660H-type charge pump supplies
negative bias to the converter circuitry, as well as to external
devices. The charge pump develops a negative output
voltage by moving charge from the power supply to the
reservoir capacitor at V
SS
by way of the commutating
capacitor connected to the CAP
+
and CAP
–
inputs.
The charge pump clock operates at a typical frequency
of 100kHz. If lower quiescent current is desired, the charge
pump clock can be slowed by connecting an external ca-
pacitor from the OSC pin to V
DD
. Reference typical charac-
teristics curves.
APPLICATIONS
Design Example
Figure 6 shows a typical TC534 interrupt-driven applica-
tion. Timing and component values are calculated from
equations and recommendations made in the Dual Slope
Integrating Converter and Programming the TC530/534
sections of this document. The EOC connection to the
processor INT input is for interrupt-driven applications only.
(In polled systems, the EOC output is available on D
OUT
).
GIVEN
REQUIRED RESOLUTION:
MAXIMUM V
IN
:
POWER SUPPLY VOLTAGE: +5V
60Hz SYSTEM
1.
Pick Integration time (t
INT
)
66msec
16 Bits (65,536 counts.)
±
2V
2.
Estimate crystal frequency
F
IN
= 2R/t
INT
= 2 x 65536/66 x 10
–3
= 1.98MHz
(use 2MHz)