TC826 TelCom Semiconductor, TC826 Datasheet
TC826
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TC826 Summary of contents
Page 1
... Full–scale differential input voltage range extends from 20mV to 2V. The TC826 sensitivity is 500 v. A low drift 35 ppm/ C internal reference, LCD backplane oscillator and driver, input polarity LCD driver, and overrange LCD driver make designs simple and low cost ...
Page 2
... TC826 ABSOLUTE MAXIMUM RATINGS* + – Supply Voltage ( ............................................ 15V (1) Analog Input Voltage (either input) Power Dissipation ( 64-Pin Flat Package .........................................1.14W Operating Temperature ‘C’ Devices ............................................. +70 C Storage Temperature ............................ – +150 C Lead Temperature (Soldering, 10 sec) ................. +300 C ELECTRICAL CHARACTERISTICS: No ...
Page 3
... NC 2 ANALOG Establishes the internal analog ground point. Analog common is set to 2.9V below the positive supply COMMON by an internal zener reference circuit. The voltage difference beween V used to supply the TC826 voltage reference input at REF IN (Pin 5). 3 +IN Positive analog signal input. 4 -IN Negative analog signal input. ...
Page 4
... Input logic signal that prevents display from changing. Pulled high internally to inactive state. Connect Input logic signal. Sets TC826 to BAR display mode. BAR 0 to 40, plus OR flash on and off. The POL– LCD driver is on. Pulled high internally to inactive state. Connect to V activate. ...
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... BAR40 POL– –IN +IN 200 FULL–SCALE 20k 20k 0.033 f 0.033 0.068 f 0.014 250k Figure 1. Typical TC826 Circuit Connection TC826 REF C REF C – REF 1 OSC1 R OSC 430k 14 OSC2 BACKPLANE ...
Page 6
... TC826 DUAL SLOPE CONVERSION PRINCIPLES The TC826 is a dual slope, integrating analog–to–digital converter. The conventional dual slope converter measure- ment cycle has two distinct phases: • Input Signal Integration • Reference Voltage Integration (Deintegration) The input signal being converted is integrated for a fixed time period (TSI) ...
Page 7
... The auto-zero loop is opened and the internal differen- tial inputs connect to +IN and –IN. The differential input signal is integrated for a fixed time period. The TC826 signal integration period is 20 clock periods or counts. The exter- nally set clock frequency is divided by 32 before clocking the internal counters ...
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... AUTO–ZERO SIGNAL PHASE (AZ) INTEGRATE PHASE (SI) TRUE ZERO CROSSING COUNTS 20 MINIMUM COUNTS ONE CONVERSION CYCLE = 80 COUNTS ( T CONV = 80 X Figure 5. TC826 Conversion Has Three Phases A/D CONVERTER WITH OSC is the externally set clock frequency. OSC V 10mV 2V REFERENCE INTEGRATE PHASE (RI) ...
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... The typical range is V Common–mode voltages are removed from the system when the TC826 operates from a battery or floating power source (Isolated from measured system) and –IN is con- nected to analog–common (V In systems where common– ...
Page 10
... Figure 7. TC826 Transfer Function BAR/DOT Input (Pin 61) The BAR/DOT input allows the user to select the display format. The TC826 powers up in the BAR mode. Select the DOT display format by connecting BAR/DOT to the negative supply (Pin 12) through a 1M resistor. HOLD Input (Pin 62) ...
Page 11
... BAR 0 POWER BAR Format SUPPLY The TC826 power-ups in the BAR mode. BAR/DOT is pulled high internally. This display format is similar to a thermometer display. All bars/LCD segments, including zero, below the bar/LCD segment equaling the input signal level are on. A half-scale input signal, for example, would displayed with BAR 0 to BAR 20 on ...
Page 12
... A/D CONVERTER WITH BAR GRAPH DISPLAY OUTPUT LCD BACKPLANE DRIVER (PIN 15) Additional drive electronics is not required to interface the TC826 to an LCD display. The TC826 has an on-chip backplane generator and driver. The backplane frequency is: FBP = FOSC/256 Figure 11 gives typical backplane driver rise/fall time versus backplane capacitance ...