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TC500COE View Datasheet(PDF) - TelCom Semiconductor Inc => Microchip

Part NameTC500COE TelCom-Semiconductor
TelCom Semiconductor Inc => Microchip TelCom-Semiconductor
DescriptionPRECISION ANALOG FRONT ENDS
TC500COE Datasheet PDF : 17 Pages
First Prev 11 12 13 14 15 16 17
PRECISION ANALOG FRONT ENDS
1 TC500
TC500A
TC510
TC514
Design Example
Given:
Required Resolution: 16 Bits (65,536 counts).
Maximum VIN:
±2V
Power Supply Voltage: +5V
60Hz System
Step 1: Pick integration time (tINT) as a multiple of the
line frequency:
1/60Hz = 16.6msec. Use 4x line frequency = 66msec
Step 2: Calculate RINT
RINT (in M) = VINMAX/20 = 2/20 = 100k
Step 3: Calculate CINT for maximum (4V) integrator
output swing:
CINT (in µF) = (tINT) (20 x 10 –6) / (VS – 0.9)
= (.066) (20 x 10 –6) / (4.1)
= .32µF (use closest value: 0.33µF)
NOTE: TelCom recommended capacitor:
WIMA p/n: MK12 .33/63/10
Step 4: Choose CREF and CAZ based on conversion rate:
Conversions/sec
= 1/(tAZ + tINT + 2 tINT + 2msec)
= 1/(66msec + 66msec +132msec+2msec)
= 3.7 conversions/sec
From which CAZ = CREF = 0.22µF (see Table 1)
USING THE TC510/514
2 Negative Supply Voltage Converter (TC510, TC514)
A capacitive charge pump is employed to invert the
voltage on VDD for negative bias within the TC510/514. This
voltage is also available on the V–OUT pin to provide negative
bias elsewhere in the system. Two external capacitors are
required to perform the conversion.
Timing is generated by an internal state machine driven
3 from an on-board oscillator. During the first phase, capacitor
CF is switched across the power supply and charged to V+S.
This charge is transferred to capacitor C–OUT during the
second phase. The oscillator normally runs at 100kHz to
ensure minimum output ripple. This frequency can be re-
duced by placing a capacitor from OSC to VDD. The relation-
ship between the capacitor value is shown in the typical
characteristics curves at the end of this data sheet.
Analog Input Multiplexer (TC514)
4
The TC514 is equipped with a four input differential
analog multiplexer. Input channels are selected using select
inputs (A1, A0). These are high-true control signals
(i.e., channel 0 is selected when (A1, A0 = 00).
EVALUATION KIT (TC500EV)
5 The TC500EV consists of a pre-assembled, 4 inch by 6
inch printed circuit board that connects to the serial port of
any PC or dumb terminal. Design software is also included.
TC500EV helps reduce design time and optimize converter
performance. Please contact your local TelCom representa-
tive for more information.
6
NOTE: TelCom recommended capacitor:
WIMA p/n: MK12 .22/63/10
Step 5: Calculate VREF
7
VREF (in Volts) = (VS – 0.9) (CINT) (RINT)
2(tINT)
= (4.1) (0.33 x 10 –6) (105) / 2(.066)
= 1.025V
8
TELCOM SEMICONDUCTOR, INC.
3-31
Direct download click here
 

GENERAL DESCRIPTION
The TC500/500A/510/514 family are precision analog front ends that implement dual slope A/D converters having a maximum resolution of 17 bits plus sign. As a minimum, each device contains the integrator, zero crossing comparator and processor interface logic. The TC500 is the base (16 bit max) device and requires both positive and negative power supplies. The TC500A is identical to the TC500, except it has improved linearity allowing it to operate to a maximum resolution of 17 bits. The TC510 adds an on board negative power supply converter for single supply operation. The TC514 adds both a negative power supply converter and a 4 input differential analog multiplexer.

FEATURES
■ Precision (up to 17 Bits) A/D Converter "Front End"
■ 3-Pin Control Interface to Microprocessor
■ Flexible: User Can Trade-Off Conversion Speed for Resolution
■ Single Supply Operation (TC510/514)
■ 4 Input, Differential Analog MUX (TC514)
■ Automatic Input Voltage Polarity Detection
■ Low Power Dissipation ........... TC500/500A: 10mW
                                          TC510/514: 18mW
■ Wide Analog Input Range ....... ±4.2V (TC500A/510)
■ Directly Accepts Bipolar and Differential Input Signals

 

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