TC7116 TC7116A TC7117 TC7117A 3-1/2 Digit Analog-To-Digital Convereters with Hold FEATURES GENERAL DESCRIPTION Low Temperature Drift Internal Reference TC7116/TC7117 ............................ 80 ppm/C Typ. TC7116A/TC7117A ....................... 20 ppm/C Typ. Display Hold Function Directly Drives LCD or LED Display Guaranteed Zero Reading With Zero Input Low Noise for Stable Display .......... 2V or 200mV Full-Scale Range (FSR) Auto-Zero Cycle Eliminates Need for Zero Adjustment Potentiometer True Polarity Indication for Precision Null Applications Convenient 9V Battery Operation (TC7116/TC7116A) High Impedance CMOS Differential Inputs .... 1012 Low Power Operation ..................................... 10mW The TC7116A/TC7117A are 3-1/2 digit CMOS analogto-digital converters (ADCs) containing all the active components necessary to construct a 0.05% resolution measurement system. Seven-segment decoders, polarity and digit drivers, voltage reference, and clock circuit are integrated on-chip. The TC7116A drives liquid crystal displays (LCDs) and includes a backplane driver. The TC7117A drives common anode light emitting diode (LED) displays directly with an 8mA drive current per segment. These devices incorporate a display hold (HLDR) function. The displayed reading remains indefinitely, as long as HLDR is held high. Conversions continue, but output data display latches are not updated. The reference - ) is not available as it is with the TC7106/ low input (VREF - 7107. VREF is tied internally to analog common in the TC7116A/7117A devices. The TC7116A/7117A reduces linearity error to less than 1 count. Roll-over error (the difference in readings for equal magnitude but opposite polarity input signals) is below 1 count. High-impedance differential inputs offer 1 pA leakage current and a 1012 input impedance. The 15VP-P noise performance guarantees a "rock solid" reading. The auto-zero cycle guarantees a zero display reading with a 0V input. The TC7116A and TC7117A feature a precision, lowdrift internal reference, and are functionally identical to the TC7116/TC7117. A low-drift external reference is not normally required with the TC7116A/TC7117A. ORDERING INFORMATION PART CODE 6 = LCD 7 = LED TC711X X XXX } A or blank* * "A" parts have an improved reference TC Package Code (see below): Package Code Package Temperature Range CKW CLW CPL IJL 44-Pin PQFP 44-Pin PLCC 40-Pin Plastic DIP 40-Pin CerDIP 0C to +70C 0C to +70C 0C to +70C - 25C to +85C AVAILABLE PACKAGES 40-Pin PDIP 0.1 F 1 M + ANALOG 0.01 F INPUT - DISPLAY LCD DISPLAY (TC7116/7116A) HOLD 33 1 OR COMMON ANODE LED 34 DISPLAY (TC7117/7117A) + - HLDR C REF C REF 31 + 2-19 SEGMENT V IN 22-25 DRIVE TC7116/A POL 20 - 30 V IN TC7117/A BACKPLANE MINUS SIGN BP/GND 21 DRIVE 32 ANALOG COMMON 35 + V 40-Pin CDIP 24 k 28 V BUFF 47 k 0.22 F 44-Pin PQFP Formed Leads 0.47 F C 29 AZ 27 + + VREF 36 100 mV V - 26 VINT OSC2 OSC3 OSC1 39 38 COSC 40 R OSC 100 pF 9V VREF 1 k TO ANALOG COMMON (PIN 32) 3 CONVERSIONS/SEC 100 k 44-Pin Plastic Chip Carrier PLCC Figure 1. Typical TC7116/A/7/A Operating Circuit (c) 2001 Microchip Technology Inc. DS21457A TC7116/A/7117/A-7 9/17/99 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A Operating Temperature "C" Device .............................................. 0C to +70C "I" Device .......................................... - 25C to +85C Storage Temperature ............................ - 65C to +150C Lead Temperature (Soldering, 10 sec) ................. +300C ABSOLUTE MAXIMUM RATINGS* Supply Voltage TC7116/TC7116A: V+ to V- ................................. 15V TC7117/TC7117A: V+ to GND ............................. +6V V- to GND ............................ - 9V Analog Input Voltage (Either Input) (Note 1) ........ V+ to V- Reference Input Voltage (Either Input) ................. V+ to V- Clock Input TC7116/TC7116A ..................................... TEST to V+ TC7117/TC7117A ...................................... GND to V+ Package Power Dissipation, TA 70C (Note 2) CDIP .................................................................2.29W PDIP .................................................................1.23W Plastic Chip Carrier (PLCC) ..............................1.23W Plastic Quad Flat Package (PQFP) ..................1.00W *Static-sensitive device. Unused devices must be stored in conductive material. Protect devices from static discharge and static fields. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operational sections of the specifications is not implied. Exposure to Absolute Maximum Rating Conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (Note 3) Parameter Test Conditions Zero Input Reading VIN = 0V Full Scale = 200mV VIN = VREF VREF = 100mV -VIN = +VIN 200mV or 2V Ratiometric Reading Roll-Over Error (Difference in Reading for Equal Positive and Negative Readings Near Full Scale) Linearity (Maximum Deviation From Best Straight Line Fit) Common-Mode Rejection Ratio (Note 4) Noise (Peak-to-Peak Value Not Exceeded 95% of Time) Leakage Current at Input Zero Reading Drift Scale Factor Temperature Coefficient Input Resistance, Pin 1 VIL , Pin 1 VIL , Pin 1 VIH, Pin 1 Supply Current (Does Not Include LED Current for 7117/A) Analog Common Voltage (With Respect to Positive Supply) Temperature Coefficient of Analog Common (With Respect to Positive Supply) TC7116/A/7117/A-7 9/17/99 Min Typ Max Unit -- 0 -- 999 999/1000 1000 -1 0.2 +1 Digital Reading Digital Reading Counts Full Scale = 200mV or 2V -1 0.2 +1 Counts VCM = 1V, VIN = 0V Full Scale = 200mV VIN = 0V Full Scale = 200mV VIN = 0V VIN = 0V "C" Device: 0C to +70C "I" Device: -25C to +85C VIN = 199 mV "C" Device: 0C to +70C (Ext Ref = 0 ppm/C) "I" Device: -25C to +85C Note 6 TC7116/A Only TC7117/A Only Both VIN = 0V -- 50 -- V/V -- 15 -- V -- 1 10 pA -- -- 0.2 1 1 2 V/C v/C -- 1 5 ppm/C -- 30 -- -- V + - 1.5 -- -- 70 -- -- -- 0.8 2.4 3.05 3.35 V -- -- 20 80 50 -- ppm/C ppm/C 25k Between Common and Positive Supply "C" Device: 0C to +70C TC7116A/TC7117A TC7116/TC7117 2 20 ppm/C -- k Test +1.5 V GND +1.5 V -- V 1.8 mA (c) 2001 Microchip Technology Inc. DS21457A 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A ELECTRICAL CHARACTERISTICS (Cont.) Parameter Test Conditions TC7116/TC7116A ONLY Peak-to-Peak Segment Drive Voltage TC7116/TC7116A ONLY Peak-to-Peak Backplane Drive Voltage TC7117/TC7117A ONLY Segment Sinking Current (Except Pin 19) TC7117/TC7117A ONLY Segment Sinking Current (Pin 19 Only) V+ V- to = 9V (Note 5) V+ to V- = 9V (Note 5) V+ = 5V Segment Voltage = 3V V+ = 5V Segment Voltage = 3V Min Typ Max Unit 4 5 6 V 4 5 6 V 5 8 -- mA 10 16 -- mA NOTES: 1. Input voltages may exceed supply voltages, provided input current is limited to 100A. 2. Dissipation rating assumes device is mounted with all leads soldered to printed circuit board. 3. Unless otherwise noted, specifications apply at TA = +25C, fCLOCK = 48kHz. TC7116/TC7116A and TC7117/TC7117A are tested in the circuit of Figure 1. 4. Refer to "Differential Input" discussion. 5. Backplane drive is inphase with segment drive for "OFF" segment, 180 out-of-phase for "ON" segment. Frequency is 20 times conversion rate. Average DC component is less than 50mV. 6. The TC7116/TC7116A logic inputs have an internal pulldown resistor connected from HLDR, pin 1 to TEST, pin 37. The TC7117/TC7117A logic inputs have an internal pulldown resistor connected from HLDR, pin 1 to GND, pin 21. (c) 2001 Microchip Technology Inc. DS21457A 3 TC7116/A/7117/A-7 9/17/99 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A PIN CONFIGURATIONS HLDR 1 40 OSC 1 HLDR 1 40 OSC 1 D1 2 39 OSC 2 D1 2 39 C1 3 38 OSC 3 C1 3 38 OSC 3 B1 4 4 5 37 TEST + 36 V REF B1 A1 A1 5 37 TEST + 36 V REF F1 6 F1 6 G1 7 G1 7 E1 8 D2 9 35 V+ + 34 CREF - 33 CREF C2 10 B2 11 10's 100's TC7116IPL TC7116AIPL TC7117CPL TC7117ACPL (PDIP) 29 CAZ F2 13 E 2 14 28 VBUFF 27 V INT D3 15 26 V - B3 16 25 G 2 F3 17 24 C 3 E 3 18 23 A 3 22 G 3 100's 100's B2 11 32 COMMON + 31 V IN - 30 V IN A2 12 29 CAZ F2 13 E 2 14 28 VBUFF 27 V INT D3 15 26 V - B3 16 25 G 2 24 C 3 F3 17 23 A 3 22 G 3 E 3 18 1000's AB 4 19 40 44 43 V- 41 INT REF HI + V + C REF - C REF 42 BUFF REF HI 43 A/Z TEST 44 IN LO OSC 3 1 IN HI OSC 2 2 42 100's 21 BP/GND (TC7116/7117) (TC7116A/TC7117A) POL 20 (MINUS SIGN) OSC 1 D1 3 10's TC7116IJL TC7116AIJL TC7117IJL TC7117AIJL (CerDIP) HLDR C1 4 8 9 35 V+ + 34 CREF - 33 CREF NC A1 B1 5 E1 D2 C2 10 21 BP/GND (TC7116/7117) (TC7116A/TC7117A) POL 20 (MINUS SIGN) 6 32 COMMON + 31 V IN - 30 V IN A2 12 AB 4 19 1000's 1's COMMON 1's OSC 2 41 40 39 38 37 36 35 34 39 V+ NC 1 33 NC NC 2 32 G E1 9 + 38 CREF - 37 CREF D2 10 36 COMMON F1 7 G1 8 C2 11 NC 12 B2 13 A 2 14 31 C 3 OSC 3 4 30 A 3 NC 5 35 IN HI TC7116CLW TC7116ACLW TC7117CLW TC7117ACLW (PLCC) 29 G 3 34 NC OSC 2 6 33 IN LO OSC 1 7 TC7116CKW TC7116ACKW TC7117CKW TC7117ACKW HLDR 8 (FLAT PACKAGE) 32 A/Z 2 TEST 3 28 BP/ GND 27 POL 26 AB 4 25 E3 18 19 20 21 22 D3 17 E2 15 16 F2 14 A2 12 13 B2 28 C2 27 E1 26 D2 25 G1 24 F1 23 A1 21 22 POL 20 B3 18 19 G2 23 B3 C3 D 3 17 A3 24 F3 B 1 11 G3 C 1 10 29 V - NC BP/ GND 30 INT AB 4 E 2 16 E3 31 BUFF F3 F 2 15 D1 9 NOTES: 1. NC = No internal connection. 2. Pins 9, 25, 40, and 56 are connected to the die substrate. The potential at these pins is approximately V+. No external connections should be made. TC7116/A/7117/A-7 9/17/99 4 (c) 2001 Microchip Technology Inc. DS21457A 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A PIN DESCRIPTION Pin No. 40-Pin PDIP/ 40-Pin CerDIP Normal Pin No. 44-Pin Plastic Quad Flat Package 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 22 23 Symbol Description 29 30 HLDR D1 C1 B1 A1 F1 G1 E1 D2 C2 B2 A2 F2 E2 D3 B3 F3 E3 AB4 POL BP GND G3 A3 Hold pin, Logic 1 holds present display reading. Activates the D section of the units display. Activates the C section of the units display. Activates the B section of the units display. Activates the A section of the units display. Activates the F section of the units display. Activates the G section of the units display. Activates the E section of the units display. Activates the D section of the tens display. Activates the C section of the tens display. Activates the B section of the tens display. Activates the A section of the tens display. Activates the F section of the tens display. Activates the E section of the tens display. Activates the D section of the hundreds display. Activates the B section of the hundreds display. Activates the F section of the hundreds display. Activates the E section of the hundreds display. Activates both halves of the 1 in the thousands display. Activates the negative polarity display. LCD backplane drive output (TC7116/TC7116A). Digital ground (TC7117/TC7117A). Activates the G section of the hundreds display. Activates the A section of the hundreds display. 24 25 26 27 31 32 34 35 C3 G2 V- VINT 28 36 VBUFF 29 37 CAZ 30 31 32 38 39 40 - VIN + V IN COMMON Activates the C section of the hundreds display. Activates the G section of the tens display. Negative power supply voltage. Integrator output. Connection point for integration capacitor. See Integration Capacitor section for additional details. Integration resistor connection. Use a 4 k resistor for 200mV full-scale range and a 47k resistor for 2V full-scale range. The size of the auto-zero capacitor influences system noise. Use a 0.47F capacitor for 200mV full scale and a 0.047F capacitor for 2V full scale. See Auto-Zero Capacitor paragraph for more details. The analog LOW input is connected to this pin. The analog HIGH input is connected to this pin. This pin is primarily used to set the analog commonmode COMMON voltage for battery operation or in systems where the input signal is referenced to the power supply. See Analog Common paragraph for more details. It also acts as a reference voltage source. (c) 2001 Microchip Technology Inc. DS21457A 5 TC7116/A/7117/A-7 9/17/99 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A PIN DESCRIPTION (Cont.) Pin No. 40-Pin CerDIP 40-Pin PDIP Normal Pin No. 44-Pin Plastic Quad Flat Package Symbol 33 34 41 42 C-REF C+REF 35 36 43 44 V+ V+REF 37 3 TEST 38 39 40 4 6 7 OSC3 OSC2 OSC1 TC7116/A/7117/A-7 9/17/99 Description See pin 34. A 0.1F capacitor is used in most applications. If a - large, common-mode voltage exists (e.g., the VIN pin is not at analog common), and a 200mV scale is used, a 1 F capacitor is recommended and will hold the roll-over error to 0.5 count. Positive power supply voltage. The analog input required to generate a full-scale output (1999 counts). Place 100mV between pins 32 and 36 for 199.9mV full scale. Place 1V between pins 32 and 36 for 2V full scale. See paragraph on Reference Voltage. Lamp test. When pulled HIGH (to V+), all segments will be turned on and the display should read -1888. It may also be used as a negative supply for externallygenerated decimal points. See Test paragraph for more details. See pin 40. See pin 40. Pins 40, 39 and 38 make up the oscillator section. For a 48kHz clock (3 readings per sec), connect pin 40 to the junction of a 100k resistor and a 100pF capacitor. The 100k resistor is tied to pin 39 and the 100pF capacitor is tied to pin 38. 6 (c) 2001 Microchip Technology Inc. DS21457A 3-1/2 Digit Analog-To-Digital Convereters with Hold + C REF V + + VREF 34 TC7116 TC7116A TC7117 TC7117A RINT CREF - C REF 36 V BUFF 33 V 28 + 35 + LOW TEMP DRIFT 31 DE (-) INT DE (+) A/Z 27 DE (+) DE (-) V+ -3V A/Z & DE () 30 - + + TO DIGITAL SECTION COMPARATOR + - V IN 29 ZENER VREF - A/Z 32 VINT INTEGRATOR - ANALOG COMMON CINT AUTOZERO A/Z 10 A + V IN CAZ TC7116 TC7116A TC7117 TC7117A 26 INT V- Figure 3. Analog Section of TC7116/TC7116A and TC7117/TC7117A ANALOG SECTION (All Pin designations refers to 40-Pin DIP) Reference Integrate Phase The final phase is reference integrate, or deintegrate. Input low is internally connected to analog common and input high is connected across the previously charged reference capacitor. Circuitry within the chip ensures that the capacitor will be connected with the correct polarity to cause the integrator output to return to zero. The time required for the output to return to zero is proportional to the input signal. The digital reading displayed is: Figure 3 shows the block diagram of the analog section for the TC7116/TC7116A and TC7117/TC7117A. Each measurement cycle is divided into three phases: (1) autozero (A-Z), (2) signal integrate (INT), and (3) reference integrate (REF) or deintegrate (DE). Auto-Zero Phase High and low inputs are disconnected from the pins and internally shorted to analog common. The reference capacitor is charged to the reference voltage. A feedback loop is closed around the system to charge the auto-zero capacitor (CAZ) to compensate for offset voltages in the buffer amplifier, integrator, and comparator. Since the comparator is included in the loop, A-Z accuracy is limited only by system noise. The offset referred to the input is less than 10V. 1000 x Reference The positive reference voltage (V+REF) is referred to analog common. Differential Input This input can accept differential voltages anywhere within the common-mode range of the input amplifier or, specifically, from 1V below the positive supply to 1V above the negative supply. In this range, the system has a CMRR of 86 dB, typical. However, since the integrator also swings with the common-mode voltage, care must be exercised to ensure that the integrator output does not saturate. A worst- case condition would be a large, positive commonmode voltage with a near full-scale negative differential input voltage. The negative-input signal drives the integrator positive when most of its swing has been used up by the positive common-mode voltage. For these critical applica- Signal-Integrate Phase The auto-zero loop is opened, the internal short is removed, and the internal high and low inputs are connected to the external pins. The converter then integrates the differential voltages between V+IN and V -IN for a fixed time. This differential voltage can be within a wide common-mode range; 1V of either supply. However, if the input signal has no return with respect to the converter power supply, V -IN can be tied to analog common to establish the correct common-mode voltage. At the end of this phase, the polarity of the integrated signal is determined. (c) 2001 Microchip Technology Inc. DS21457A VIN . VREF 7 TC7116/A/7117/A-7 9/17/99 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A V+ V+ V+ V+ 4049 6.8 k TC7116 TC7116A TC7117 TC7117A V+REF TC7116 TC7116A BP 20k TC9491CZM TEST 1.2V REF TO LCD DECIMAL POINT 21 GND TO LCD BACKPLANE 37 COMMON Figure 5. Simple Inverter for Fixed Decimal Point Figure 4. Using an External Reference tions, the integrator swing can be reduced to less than the recommended 2V full-scale swing with little loss of accuracy. The integrator output can swing within 0.3V of either supply without loss of linearity. V+ V+ BP TC7116 TC7116A Analog Common This pin is included primarily to set the common-mode voltage for battery operation (TC7116/TC7116A) or for any system where the input signals are floating with respect to the power supply. The analog common pin sets a voltage approximately 2.8V more negative than the positive supply. This is selected to give a minimum end-of-life battery voltage of about 6V. However, analog common has some attributes of a reference voltage. When the total supply voltage is large enough to cause the zener to regulate (>7V), the analog common voltage will have a low voltage coefficient (0.001%/ %), low output impedance (15), and a temperature coefficient of less than 20 ppm/C, typically, and 50 ppm maximum. The TC7116/TC7117 temperature coefficients are typically 80 ppm/C. An external reference may be used, if necessary, as shown in Figure 4. - Analog common is also used as V IN return during auto- zero and deintegrate. If VIN is different from analog common, a common-mode voltage exists in the system and is taken care of by the excellent CMRR of the converter. However, in - some applications, VIN will be set at a fixed, known voltage (power supply common for instance). In this application, analog common should be tied to the same point, thus removing the common-mode voltage from the converter. The same holds true for the reference voltage; if it can be conveniently referenced to analog common, it should be. This removes the common-mode voltage from the reference system. Within the IC, analog common is tied to an N-channel FET that can sink 30mA or more of current to hold the voltage 3V below the positive supply (when a load is trying TC7116/A/7117/A-7 9/17/99 TO LCD DECIMAL POINTS DECIMAL POINT SELECT 4030 TEST GND Figure 6. Exclusive "OR" Gate for Decimal Point Drive TC7116/TC7116A TC7117/TC7117A 40 39 TO COUNTER 38 CRYSTAL EXT OSC RC NETWORK TO TEST PIN ON TC7116/TC7116A TO GROUND PIN ON TC7117/TC7117A Figure 7. Clock Circuits to pull the analog common line positive). However, there is only 10A of source current, so analog common may easily be tied to a more negative voltage, thus overriding the internal reference. Test The TEST pin serves two functions. On the TC7117/ TC7117A, it is coupled to the internally-generated digital supply through a 500 resistor. Thus, it can be used as a 8 (c) 2001 Microchip Technology Inc. DS21457A 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A voltage is switched. The BP frequency is the clock frequency 800. For 3 readings per second, this is a 60-Hz square wave with a nominal amplitude of 5V. The segments are driven at the same frequency and amplitude, and are inphase with BP when OFF, but out-of-phase when ON. In all cases, negligible DC voltage exists across the segments. Figure 9 is the digital section of the TC7117/TC7117A. It is identical to the TC7116/TC7116A, except that the regulated supply and BP drive have been eliminated, and the segment drive is typically 8 mA. The 1000's output (pin 19) sinks current from two LED segments, and has a 16-mA drive capability. The TC7117/TC7117A are designed to drive common anode LED displays. In both devices, the polarity indication is ON for analog inputs. If V -IN and V +IN are reversed, this indication can be reversed also, if desired. negative supply for externally-generated segment drivers, such as decimal points or any other presentation the user may want to include on the LCD. (Figures 5 and 6 show such an application.) No more than a 1mA load should be applied. The second function is a "lamp test." When TEST is pulled HIGH (to V+), all segments will be turned ON and the display should read -1888. The TEST pin will sink about 10 mA under these conditions. DIGITAL SECTION Figures 8 and 9 show the digital section for TC7116/ TC7116A and TC7117/TC7117A, respectively. For the TC7116/TC7116A (Figure 8), an internal digital ground is generated from a 6V zener diode and a large P-channel source follower. This supply is made stiff to absorb the relative large capacitive currents when the backplane (BP) TC7116 TC7116A BACKPLANE 21 LCD PHASE DRIVER TYPICAL SEGMENT OUTPUT + V 7-SEGMENT DECODE 0.5mA 7-SEGMENT DECODE 7-SEGMENT DECODE / 200 SEGMENT OUTPUT LATCH 2mA INTERNAL DIGITAL GROUND THOUSANDS TENS HUNDREDS UNITS TO SWITCH DRIVERS FROM COMPARATOR OUTPUT 35 70k CLOCK /4 LOGIC CONTROL VTH = 1V 40 OSC 1 39 OSC 2 38 INTERNAL DIGITAL GROUND OSC 3 6.2V 37 + TEST 500 26 1 V V- HLDR Figure 8. TC7116/TC7116A Digital Section (c) 2001 Microchip Technology Inc. DS21457A 9 TC7116/A/7117/A-7 9/17/99 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A System Timing To achieve maximum rejection of 60-Hz pickup, the signal-integrate cycle should be a multiple of 60Hz. Oscillator frequencies of 240kHz, 120kHz, 80kHz, 60kHz, 48kHz, 40kHz, etc. should be selected. For 50Hz rejection, oscillator frequencies of 200kHz, 100kHz, 66-2/3kHz, 50kHz, 40kHz, etc. would be suitable. Note that 40kHz (2.5 readings per second) will reject both 50Hz and 60Hz. The clocking method used for the TC7116/TC7116A and TC7117/TC7117A is shown in Figure 9. Three clocking methods may be used: (1) An external oscillator connected to pin 40. (2) A crystal between pins 39 and 40. (3) An RC network using all three pins. HOLD Reading Input The oscillator frequency is before it clocks the decade counters. It is then further divided to form the three convert-cycle phases: signal integrate (1000 counts), reference deintegrate (0 to 2000 counts), and auto-zero (1000 to 3000 counts). For signals less than full scale, auto-zero gets the unused portion of reference deintegrate. This makes a complete measure cycle of 4000 (16,000 clock pulses) independent of input voltage. For 3 readings per second, an oscillator frequency of 48kHz would be used. When HLDR is at a logic HIGH the latch will not be updated. Analog-to-digital conversions will continue but will not be updated until HLDR is returned to LOW. To continuously update the display, connect to test (TC7116/TC7116A) or ground (TC7117/TC7117A), or disconnect. This input is CMOS compatible with 70k typical resistance to TEST (TC7116/TC7116A) or ground (TC7117/TC7117A). TC7117 TC7117A TYPICAL SEGMENT OUTPUT + V 7-SEGMENT DECODE 0.5mA 7-SEGMENT DECODE 7-SEGMENT DECODE TO SEGMENT 8mA LATCH DIGITAL GROUND THOUSANDS V+ HUNDREDS TENS UNITS TO SWITCH DRIVERS FROM COMPARATOR OUTPUT 35 CLOCK /4 CONTROL LOGIC OSC 1 39 OSC 2 38 1 OSC 3 TEST 500 21 40 V+ 37 DIGITAL GND ~70k HLDR Figure 9. TC7117/TC7117A Digital Section TC7116/A/7117/A-7 9/17/99 10 (c) 2001 Microchip Technology Inc. DS21457A 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A COMPONENT VALUE SELECTION Auto-Zero Capacitor Reference Voltage To generate full-scale output (2000 counts), the analog input requirement is VIN = 2 VREF. Thus, for the 200mV and 2V scale, VREF should equal 100mV and 1V, respectively. In many applications, where the ADC is connected to a transducer, a scale factor exists between the input voltage and the digital reading. For instance, in a measuring system the designer might like to have a full-scale reading when the voltage from the transducer is 700mV. Instead of dividing the input down to 200 mV, the designer should use the input voltage directly and select VREF = 350mV. Suitable values for integrating resistor and capacitor would be 120k and 0.22F. This makes the system slightly quieter and also avoids a divider network on the input. The TC7117/TC7117A, with 5V supplies, can accept input signals up to 4V. Another advantage of this system is when a digital reading of zero is desired for VIN 0. Temperature and weighing systems with a variable tare are examples. This offset reading can be conveniently generated by connecting the voltage transducer between V+IN and analog common, and the variable (or fixed) offset voltage between analog com- mon and V IN . The size of the auto-zero capacitor has some influence on system noise. For 200mV full scale, where noise is very important, a 0.47F capacitor is recommended. On the 2V scale, a 0.047F capacitor increases the speed of recovery from overload and is adequate for noise on this scale. Reference Capacitor A 0.1F capacitor is acceptable in most applications. However, where a large common-mode voltage exists - pin is not at analog common), and a 200-mV (i.e., the V IN scale is used, a larger value is required to prevent roll-over error. Generally, 1 F will hold the roll-over error to 0.5 count in this instance. Integrating Capacitor The integrating capacitor should be selected to give the maximum voltage swing that ensures tolerance buildup will not saturate the integrator swing (approximately 0.3V from either supply). In the TC7116/TC7116A or the TC7117/ TC7117A, when the analog common is used as a reference, a nominal 2V full- scale integrator swing is acceptable. For the TC7117/TC7117A, with 5V supplies and analog common tied to supply ground, a 3.5V to 4V swing is nominal. For 3 readings per second (48kHz clock), nominal values for CINT are 0.221F and 0.10F, respectively. If different oscillator frequencies are used, these values should be changed in inverse proportion to maintain the output swing. The integrating capacitor must have low dielectric absorption to prevent roll-over errors. Polypropylene capacitors are recommended for this application. TC7117/TC7117A POWER SUPPLIES The TC7117/TC7117A are designed to operate from 5V supplies. However, if a negative supply is not available, it can be generated with a TC7660 DC-to-DC converter and two capacitors. Figure 10 shows this application. In selected applications, a negative supply is not required. The conditions for using a single +5V supply are: (1) The input signal can be referenced to the center of the common-mode range of the converter. (2) The signal is less than 1.5V. (3) An external reference is used. Integrating Resistor +5V Both the buffer amplifier and the integrator have a class A output stage with 100A of quiescent current. They can supply 20A of drive current with negligible nonlinearity. The integrating resistor should be large enough to remain in this very linear region over the input voltage range, but small enough that undue leakage requirements are not placed on the PC board. For 2V full scale, 470k is near optimum and, similarly, 47k for 200mV full scale. 35 36 V+ V+ REF LED DRIVE COM TC7117 TC7117A 2 Oscillator Components DS21457A TC7660 10F For all frequency ranges, a 100k resistor is recommended; the capacitor is selected from the equation: f = 45 . RC For a 48 kHz clock (3 readings per second), C = 100pF. (c) 2001 Microchip Technology Inc. - GND + 5 (-5V) 4 32 + 31 V IN - V IN 8 TC04 30 21 + V IN - V 26 3 + 10F Figure 10. Negative Power Supply Generation With TC7660 11 TC7116/A/7117/A-7 9/17/99 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A TYPICAL APPLICATIONS 40 39 38 37 36 35 34 33 32 31 TC7116 TC7116A 30 29 28 27 26 25 24 23 22 21 SET VREF = 100mV V+ TO LOGIC VCC 100pF 22k 0.1pF 1k 1M + 26 V- - 47k 9V O/R - 0.22F U/R 20 TO DISPLAY 21 CD4023 OR 74C10 O/R = OVERRANGE U/R = UNDERRANGE CD4077 TO BACKPLANE Figure 13. Circuit for Developing Underrange and Overrange Signals from TC7116/TC7116A Outputs SET VREF = 100mV 100k 40 39 38 37 36 35 34 33 32 31 TC7117 30 TC7117A 29 28 27 26 25 24 23 22 21 100pF 22k 0.1pF +5V 1k 1M + IN 0.01F 0.47F 0.22F 47k - -5V TO DISPLAY Figure 12. TC7117/TC7117A Internal Reference (200mV Full Scale, - 3 RPS, VIN Tied to GND for Single-Ended Inputs.) TC7116/A/7117/A-7 9/17/99 TO LOGIC GND IN 0.01F 0.47F 35 TC7116 TC7116A + Figure 11. TC7116/TC7116A Using the Internal Reference (200mV Full Scale, 3 Readings Per Second (RPS) 40 39 38 37 36 35 34 33 32 31 TC7117 30 TC7117A 29 28 27 26 25 24 23 22 21 40 100k 100k SET VREF = 100 mV 100pF 10k 0.1pF 1k 1.2V 0.01F 10k + V TC9491CZM + IN 1M 0.47F 47k - 0.22F V - TO DISPLAY Figure 14. TC7117/TC7117A With a 1.2V External Band-Gap - Reference (VIN Tied to Common) 12 (c) 2001 Microchip Technology Inc. DS21457A 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 TC7116 TC7116A TC7117 TC7117A SET VREF = 1V 100k 100pF 24k 0.1F 25k 1M 0.01F 0.047F V+ + IN TC7117 TC7117A - 470k 0.22F V- TO DISPLAY Figure 15. Recommended Component Values for 2V Full Scale (TC7116/TC7116A and TC7117/TC7117A) 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 100k SET VREF = 100mV 100pF 10k 0.1pF 1k 1.2V 0.01F 0.47F 10k + V TC9491CZM + IN 1M - 47k 0.22F TO DISPLAY Figure 16. TC7117/TC7117A Operated from Single +5V Supply (An External Reference Must Be Used in This Application.) APPLICATIONS INFORMATION are ON) to Point C of Figure 17. When segments turn off, the output voltage will increase. The diode, however, will result in a relatively steady output voltage, around Point B. In addition to limiting maximum power dissipation, the resistor reduces change in power dissipation as the display changes. The effect is caused by the fact that, as fewer segments are ON, each ON output drops more voltage and current. For the best case of six segments (a "111" display) to worst case (a "1888" display), the resistor circuit will change about 230mW, while a circuit without the resistor will change about 470mW. Therefore, the resistor will reduce the effect of display dissipation on reference voltage drift by about 50%. The change in LED brightness caused by the resistor is almost unnoticeable as more segments turn off. If display brightness remaining steady is very important to the designer, a diode may be used instead of the resistor. The TC7117/TC7117A sink the LED display current, causing heat to build up in the IC package. If the internal voltage reference is used, the changing chip temperature can cause the display to change reading. By reducing the LED common anode voltage, the TC7117/TC7117A package power dissipation is reduced. Figure 17 is a curve-tracer display showing the relationship between output current and output voltage for typical TC7117CPL/TC7117ACPL devices. Since a typical LED has 1.8V across it at 8mA and its common anode is connected to +5V, the TC7117/TC7117A output is at 3.2V (Point A, Figure 17). Maximum power dissipation is 8.1mA x 3.2V x 24 segments = 622mW. However, notice that once the TC7117/TC7117A's output voltage is above 2V, the LED current is essentially constant as output voltage increases. Reducing the output voltage by 0.7V (Point B Figure 17) results in 7.7mA of LED current, only a 5% reduction. Maximum power dissipation is now only 7.7mA x 2.5V x 24 = 462mW, a reduction of 26%. An output voltage reduction of 1V (Point C) reduces LED current by 10% (7.3mA), but power dissipation by 38% (7.3mA x 2.2V x 24 = 385mW). Reduced power dissipation is very easy to obtain. Figure 18 shows two ways: Either a 5.1, 1/4W resistor, or a 1A diode placed in series with the display (but not in series with the TC7117/TC7117A). The resistor reduces the TC7117/TC7117A's output voltage (when all 24 segments (c) 2001 Microchip Technology Inc. DS21457A 13 TC7116/A/7117/A-7 9/17/99 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A +5V + -5V IN - 1M 24k 150k TP3 1k 100 pF TP5 100 k 40 0.01 F TP2 0.1 F TP1 0.22 F DISPLAY 47 k 35 30 TC7117 TC7117A 1 0.47 F TP 4 10 21 20 DISPLAY 1.5, 1/4W 1N4001 Figure 17. TC7117/TC7117A Output Current vs. Output Voltage TC7116/A/7117/A-7 9/17/99 Figure 18. Diode or Resistor Limits Package Power Dissipation 14 (c) 2001 Microchip Technology Inc. DS21457A 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A PACKAGE DIMENSIONS (Cont.) 40-Pin PDIP PIN 1 .555 (14.10) .530 (13.46) 2.065 (52.45) 2.027 (51.49) .610 (15.49) .590 (14.99) .200 (5.08) .140 (3.56) .040 (1.02) .020 (0.51) .150 (3.81) .115 (2.92) .110 (2.79) .090 (2.29) .070 (1.78) .045 (1.14) .015 (0.38) .008 (0.20) 3 MIN. .700 (17.78) .610 (15.50) .022 (0.56) .015 (0.38) 40-Pin CDIP PIN 1 .540 (13.72) .510 (12.95) .030 (0.76) MIN. .098 (2.49) MAX. 2.070 (52.58) 2.030 (51.56) .620 (15.75) .590 (15.00) .060 (1.52) .020 (0.51) .210 (5.33) .170 (4.32) .150 (3.81) MIN. .200 (5.08) .125 (3.18) .110 (2.79) .090 (2.29) (c) 2001 Microchip Technology Inc. DS21457A .065 (1.65) .045 (1.14) .015 (0.38) .008 (0.20) 3 MIN. .700 (17.78) .620 (15.75) .020 (0.51) .016 (0.41) Dimensions: inches (mm) 15 TC7116/A/7117/A-7 9/17/99 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A PACKAGE DIMENSIONS (Cont.) 44-Pin PLCC PIN 1 .021 (0.53) .013 (0.33) .050 (1.27) TYP. .695 (17.65) .685 (17.40) .630 (16.00) .591 (15.00) .656 (16.66) .650 (16.51) .032 (0.81) .026 (0.66) .020 (0.51) MIN. .656 (16.66) .650 (16.51) .120 (3.05) .090 (2.29) .695 (17.65) .685 (17.40) .180 (4.57) .165 (4.19) 44-Pin PQFP 7 MAX. .009 (0.23) .005 (0.13) PIN 1 .018 (0.45) .012 (0.30) .041 (1.03) .026 (0.65) .398 (10.10) .390 (9.90) .557 (14.15) .537 (13.65) .031 (0.80) TYP. .010 (0.25) TYP. .398 (10.10) .390 (9.90) .083 (2.10) .075 (1.90) .557 (14.15) .537 (13.65) .096 (2.45) MAX. Dimensions: inches (mm) TC7116/A/7117/A-7 9/17/99 16 (c) 2001 Microchip Technology Inc. DS21457A 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A TAPE & REEL DIMENSIONS Component Taping Orientation for 44-Pin PLCC Devices User Direction of Feed User Direction of Feed PIN 1 W PIN 1 P Standard Reel Component Orientation for TR Suffix Device Reverse Reel Component Orientation for RT Suffix Device Carrier Tape, Number of Components Per Reel and Reel Size Package 44-Pin PLCC Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size 32 mm 24 mm 500 13 in NOTE: Drawing does not represent total number of pins. Component Taping Orientation for 44-Pin PQFP Devices User Direction of Feed User Direction of Feed PIN 1 W PIN 1 Standard Reel Component Orientation for TR Suffix Device P Reverse Reel Component Orientation for RT Suffix Device Carrier Tape, Number of Components Per Reel and Reel Size Package 44-Pin PQFP Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size 24 mm 16 mm 500 13 in NOTE: Drawing does not represent total number of pins. (c) 2001 Microchip Technology Inc. DS21457A 17 TC7116/A/7117/A-7 9/17/99 3-1/2 Digit Analog-To-Digital Convereters with Hold TC7116 TC7116A TC7117 TC7117A WORLDWIDE SALES AND SERVICE AMERICAS New York ASIA/PACIFIC (continued) Corporate Office 150 Motor Parkway, Suite 202 Hauppauge, NY 11788 Tel: 631-273-5305 Fax: 631-273-5335 Singapore 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: 480-792-7627 Web Address: http://www.microchip.com Rocky Mountain 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7966 Fax: 480-792-7456 San Jose Microchip Technology Inc. 2107 North First Street, Suite 590 San Jose, CA 95131 Tel: 408-436-7950 Fax: 408-436-7955 Microchip Technology Singapore Pte Ltd. 200 Middle Road #07-02 Prime Centre Singapore, 188980 Tel: 65-334-8870 Fax: 65-334-8850 Taiwan Atlanta 6285 Northam Drive, Suite 108 Mississauga, Ontario L4V 1X5, Canada Tel: 905-673-0699 Fax: 905-673-6509 500 Sugar Mill Road, Suite 200B Atlanta, GA 30350 Tel: 770-640-0034 Fax: 770-640-0307 Microchip Technology Taiwan 11F-3, No. 207 Tung Hua North Road Taipei, 105, Taiwan Tel: 886-2-2717-7175 Fax: 886-2-2545-0139 ASIA/PACIFIC Austin EUROPE China - Beijing Australia Analog Product Sales 8303 MoPac Expressway North Suite A-201 Austin, TX 78759 Tel: 512-345-2030 Fax: 512-345-6085 Boston 2 Lan Drive, Suite 120 Westford, MA 01886 Tel: 978-692-3848 Fax: 978-692-3821 Boston Analog Product Sales Unit A-8-1 Millbrook Tarry Condominium 97 Lowell Road Concord, MA 01742 Tel: 978-371-6400 Fax: 978-371-0050 Toronto Microchip Technology Beijing Office Unit 915 New China Hong Kong Manhattan Bldg. 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No licenses are conveyed, implicitly or otherwise, except as maybe explicitly expressed herein, under any intellectual property rights. The Microchip logo and name are registered trademarks of Microchip Technology Inc. in the U.S.A. and other countries. All rights reserved. All other trademarks mentioned herein are the property of their respective companies. TC7116/A/7117/A-7 9/17/99 18 (c) 2001 Microchip Technology Inc. DS21457A