ADD3501 NSC | Alldatasheet
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. i=] National 8 Semiconductor = ADD3501 314 Digit DVM with Multiplexed 7-Segment Output General Description Features The ADD3501 monolithic DVM circuit is manufactured using ™@ Operates from single 5V supply ‘standard complementary MOS (CMOS) technology. A pulse ™ Converts OV to +1.999V modulation analog-to-digital conversion technique is used ™ Multiplexed 7-segment and requires no external precision components. In addition, ™ Drives segments directly this technique allows the use of a reference voltage that is @ No external precision component necessat " ry the same polarity as the input voltage. ; ™ Accuracy specified over temperature One 5V (TTL) power supply is required. Operating withan Medium speed - 200ms/conversion isolated supply allows the conversion of positive as well 25 internal clock set with RC network or driven externally negative voltages. The sign of the input voltage is automati- ov Indicated OFL OFL displ de cally determined and output on the sign pin. If the power “ ora Ot ey TOFL or — Replay rea supply is not isolated, only one polarity of voltage may be ing and C output converted. ™ Analog inputs in applications shown can withstand , i i - £200 Volts The conversion rate is set by an internal oscillator. The fre- quency of the oscillator can be set by an external RC net- % ADD3501 equivalent to MM74C935 work or the oscillator can be driven from an external fre- . quency source. When using the extemal RC network, a Applications square wave output is available. It is important to note that + ™ Low cost digital power supply readouts great care has been taken to synchronize digit multiplexing ™ Low cost digital multimeters with the A/D conversion timing to eliminate noise due to = Low cost digital panel meters Power supply transients. ™ Eliminate analog multiplexing by using remote A/D con- The ADD3501 has been designed to drive 7-segment multi- verters Plexed LED displays directly with the aid of external digit m Convert analog transducers (temperature, pressure, dis- buffers and segment resistors. Under condition of over- placement, etc.) to digital transducers range, the overflow output will go high and the display will read +OFL or —OFL, depending on whether the input volt- age is positive or negative. In addition to this, the most sig- nificant digit is blanked when zero. A start conversion input and a conversion complete output are included on all 4 versions of this product. oo SSSSSSSSSsSSSSSSSSSSSSSSSSSSSSSees Connection Diagram veer Fe AWALOG Voc — 2 ay an sto 3 | Sa 2sf-— cno ss 24b— biGit 1 (so) Ss 2ap— pair 2 FLO gpoases = 22, — Oui CONVERSION compLETE —| y 21} DIGIT 4uso) START CONVERSION I g 20}— tour SIGN — 19 19} tn Venter 11 1h vaer Vint) 4 32 oo Vint) ia 16E— sw Vea—tu 15,— ANALOG GHO TU/H/5681—1 Order Number ADD3501CCN See NS Package Number N28B 3-259
8 Absolute Maximum Ratings (note 1)
8 It Milltary/Aerospace specified devices are required, Package Dissipation at Ta = 25°C 800 mw
< please contact the National Semiconductor Sales derate at 9 jamax)= 125°C/Watt Office/Distributors for availability and specifications. above Ta=25°C Voltage at Any Pin —0.3V to Veco +0.3V Operating Voc Range 4.5V to 6.0V Operating Temperature Range (Ta) —40°C to +85°C Absolute Maximum Voc 6.5V ESD Susceptibility (Note 3) TBDV Lead Temp. (Soldering, 10 seconds) 260°C Storage Temperature Range —65°C to + 150°C Electrical Characteristics aposs0: 4.75V < Voc < 5.25V, —40°C < Ta < +85°C, unless otherwise specified. symboi | __ Parameter | condone [wn | Tyo) | wax | Unt Vian» | tovica"t"inputvotage [foots | TT Vive) Lovic!“orinputvonage | TT Tv Voutio) | Logical 0" Output Voltage Ig=1.1 mA (All Digital Outputs except v Digit Outputs) Voutio) | Logical “0” Output Voltage Io=0.7 mA v (Digit Outputs) Vour(1) | Logical “1” Output Voltage Ip=50 MA@Ty=25°C Voc=5V | Voc-1.6 | Voc-1.3 v (All Segment Outputs) Ig=30 mA@Ty= 100°C Voo-1.6 Veo—1.3 Vv Vour(1) | Logical 1” Output Voltage | Io =500pA (Digit Outputs) (All Digital Outputs except 19 =360pA (Conv. Complete, Voc—0.4 v Segment Outputs) +/—, Oflo Outputs) lsource | Output Source Current Vout= 1.0V mA (Digit Outputs) in) Logical “1” Input Current Vin=1.5V HA (Start Conversion) lino) Logical “O” Input Current Vin=0V BA (Start Conversion) too | Supply Current Sogmenisand Digits Open || 08 | 10 | ma toso | Oseilater Frequency ee fw | Glock Frequency ee to | Corversnnate | TT toast || conv.lsee twux | Digit Mux Rate a taank | InterDigtslankingtime [Testo || see tscow | Stat Convrsin Pusewan |S | ns Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating the device beyond its specified operating conditions. Note 2: All typicals given for Ta = 25°C. Note 3: Human body model, 100 pF discharged through a 1.5 k01 resistor. 3-260
| [=] Electrical Characteristics aposs01 9 tc=5 conversions/second, 0°C<T,<70°C, unless otherwise specified. & Parameter [| conaitions | win tye Tax | Unite Non-Linearity Vin=0-—2V Full Scale —0,05 +0.025 +0.05 % of Vin=0—200mV Full Scale —0.05 +0.025 +0.05 full scale Quantzatonemor | Pt 0 courts Oftecterorvw=ov [| Tmo Ts [ts Tw Rollover Error poo 0 courts Analog input Current Ta=25°C £05 nA Win+, Vin-) Block Diagram ADD3501 3'/,-Digit DVM Block Diagram ater o — [>o & 1 od sel ae Pi — mpl secomextt 1? % te, =F 4 eee bl — — pos a — | [po y iy HH Dw ee -—| Ht es P maven a |_| Te 4 oPpo—e ners aw TT TT vor ann | TT po ater ais, foe EL comanaron iy + = el as L| | Y eveeroe 3 DIGITAL Ver, CONV COMPLETE na mee ee et ren E ; -! on vin {+] in 4 . 1 i (-} to va Tuhvs68-2 3-261
8 Theory of Operation
‘SW1 a square wave pulse train with positive amplitude Vrer For the ADD3501, N= 2000. Figure 1. Analog Loop Schematic
S | Applications
8 SYSTEM DESIGN CONSIDERATIONS
< Perhaps the most important thing to consider when design- the jitter rather than decrease it. The most important char- ing a system using the ADD3501 is power supply noise on acteristic of transients on the Vcc line is the duration of the the Vcc and ground lines. Because a single power supply is transient and not its amplitude. used and currents in the 300 mA range are being switched, Figure 4 shows a DPM system which converts OV to 1.999V good circuit layout techniques cannot be overemphasized. operating from a non-isolated power supply. In this configu- Great care has been exercised in the design of the ration the sign output could be + (logic “1”) or — (logic ADD3501 to minimize these problems but poor printed cir- “0”) and it should be ignored. Higher voltages could be con- cuit tayout can negate these features. verted by placing a fixed divider on the input; lower voltages Figures 4, 5, and 6 show schematics of DVM systems. An could be converted by placing a fixed divider on the feed- attempt has been made to show, on these schematics, the back, as shown in Figure 6. proper distribution for ground and Vcc. To help isolate digi- Figures 5 and 6 show systems operating with an isolated tal and analog portions of the circuit, the analog Voc and supply that will convert positive and negative inputs. 60 Hz ground have been separated from the digital Voc and common mode input becomes a problem in this configura- ground. Care must be taken to eliminate high current from tion and a transformer with an electrostatic shield between flowing in the analog Vc and ground wires. The most effec- primary and secondary windings Is shown, The necessity for tive method of accomplishing this is to use a single ground using a shielded transformer depends on the performance point and a single Vcc point where all wires are brought requirements and the actual application. together. In addition to this the conductors must be of suffi- The filter capacitors connected to Veg (pin 14) and Vett lent size to prevent significant voltage drops, (pin 11) should be low leakage. In the application examples To prevent switching noise from causing jitter problems, a shown every 1.0nA of leakage current will cause 0.1mV er- voltage regulator with good high frequency response is nec- ror (1.0X 10-9AX 100k. =0.1m\\). if the leakage current in essary. The LM309 and the LM340-5 voltage regulators both capacitors is exactly the same no error will result since both function well and are shown in Figures 4, 5, and 6. the source impedances driving them are matched. Adding more filtering than is shown will in general increase . 3-264
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