RC4151TC | DigiCamel IC Datasheet

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RC4151 FAIRCHILD | Alldatasheet

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wA4151 ¢ 4A7151 FAIRCHILD LINEAR INTEGRATED CIRCUITS DESCRIPTION ~ The 1A4151 is a monolithic building block used to convert de voltage to digital pulses. The frequency of the output pulses is proportional to the de input voltage. eaaainenenaiaie” The 1A4151 consists of a voltage comparator, a monostable multivibrator and a precision (TOP view) switched current source (see block diagram). PACKAGE OUTLINES 6A 9A ‘The 1A7151 is the same device as the 4.44151 with a high performance operational amplifier PACKAGE CODES =D P ‘on the same chip. The single supply op amp conditions the input signal and provides a significant improvement in system performance. 7 . ‘@ SINGLE SUPPLY (+8 Voc TO +30 Voc) ood. Broa, @ LINEARITY TO +0.05% orane, “Ht ouem © PROGRAMMABLE SCALE FACTOR ont © PULSE OUTPUT COMPATIBLE WITH ANY LOGIC FORM teotoe peor @ TEMPERATURE STABILITY TYPICALLY +100 ppm/°C @ HIGH NOISE REJECTION © EASILY TRANSMITTABLE OUTPUT @ SIMPLE FULL-SCALE TRIM ORDER INFORMATION © SINGLE-ENDED INPUT, REFERENCED TO GROUND TYPE PART NO. * ALSO PROVIDES FREQUENCY-TO-VOLTAGE CONVERSION ‘¢ HIGH PERFORMANCE OP AMP INCLUDED IN 1A7151 BATISY BATIBIPC 8-PIN MINI DIP (TOP VIEW) PACKAGE OUTLINES 9T ABSOLUTE MAXIMUM RATINGS PACKAGE CODES T Supply Voltage 32V Internal Power Dissipation 670 mW —~ Input Voltage (Comparator) -02 Vto +Vcc wet the Input Voltage (Op Amp) -0.2 V to +Vec ee: ww Logic Out Shorted-to-Ground continuous ees «resco Op Amp Out Shorted-to-Ground continuous cores geser Op Amp input Common Mode Voltage Range +13 V to Vs Op Amp Output Voltage Range, Ry = 10k +2VI0 H13V Operating Temperature Range 0°C to +70°C Storage Temperature Range 65°C to +150°C ORDER INFORMATION Pin Temperatures Molded DIP (Soldering, 10 s) 260°C nies Parent Hermetic DIP (Soldering, 60 s) 300°C M @-PIN METAL CAN (TOP VIEW) PACKAGE OUTLINE 5S PACKAGE CODE —-H ORDER INFORMATION TYPE PART NO. BAAS BASISIHC 5-15

FAIRCHILD @ 44151 © 4A7151 ELECTRICAL CHARACTERISTICS: Vcc = +15 V, Ta = 25°C unless otherwise specified. ‘The following specs apply to the Converter Section only. CHARACTERISTICS CONDITIONS MIN TYP MAX UNITS B.0V< Voc < 15V 30 45 70 ‘Supply Current 15V < Vcc <= 22V 30 55 85 mA 22V < Voc < 30V 3.0 65 10.5 Conversion Accuracy ‘Scale Factor Figure 2, Vy = 10 V, Rg = 14k 0.90 10 1.40 kKHZ/V Drift with Temperature Figure 2, V; = 10V +100 ppm/°C Drift with Voc, Figure 2, 8.0 V = Voc < 18 V, Vy = 1.0V 02 1.0 %N Input Comparator Offset Voltage 50 10 mv Offset Current +50 ‘+100 nA Input Bias Current —100 -300 nA ‘Common Mode Range (Note 1) oto | Vec-30] Vv Veo-2 One-Shot ‘Threshold Voltage, Pin 5 0.63 0.667 0.70 xVec Input Bias Current, Pin 5 —100 ~500 mA Reset Veat 0.15 0.50 v Current Source Output Current (Vg—14 k) Pin 1, Figure 1, V = 0 138.7 BA Change with Voltage Pin 1,V=OVtoV=10V 10 25 HA Off Leakage Pin 1, V=0V¥ 10 50 nA Reference Voltage Pin 2, Figure 1 19 2.08 v Logic Output Veat Pin 3,1 = 3.0 mA 0.15 0.50 v Vsat Pin 3,1 = 2.0 mA 0.10 0.35 v Off Leakage 01 1.0 pA NOTE 1; Input common mode range inchides ground. uAT151 Op-Amp ELECTRICAL CHARACTERISTICS: Vs = +15 V and ground T, = 25°C unless otherwise specified. CHARACTERISTICS MN] P| OMAX | __UNITS Input Ofset Votage | 2e [so |v Input Oftset Current [wo | | ut as Core a ated oe a ‘Common Mode Rejection Ratio 70 9 dB Large Signal Voltage Gain, Ry = 10k 50 200 Viv ‘Slew Rate 06 Vins Power Supply Rejection Ratio 15 BV Output Short Circuit Current 10 mA 5-16

FAIRCHILD @ 1.A4151 @ 4A7151 CIRCUIT DESCRIPTION The 1A7151 consists of five circuit blocks as shown in Figure 1. The blocks may be connected in a variety of ways to construct voltage-to-trequency converters (VFC), frequency-to-voltage converters (FVC), or other circuit functions. The circuit blocks are: 1. A differential input comparator featuring very high gain, low offsets, and a common mode range which includes ground. 2. A one-shot multivibrator with the time constant set by an external RC (T = 1.1RC) connected to the RC terminal, triggered by the output of the comparator being high. 3. A precision switched current source that is turned on to the value of Iaer when the one-shot is ‘on and goes to zero when the one-shot is off. The current Iner is set by an external Rg, con- nected from the scale factor terminal-to-ground and is equal to the reference voltage divided by Rg and is optimized when set to 138 4A 4, An open collector output that provides a buffered output from the one-shot. 5. An operational amplifier whose common mode range includes ground and has offset null capa- bility. The op amp has high gain, low offset voltage, low input currents, good PSRR and CMRR, and low dit. PRINCIPLE OF OPERATION Voltage to Frequency Conversion (VFC) As a voltage to frequency converter the 4A7151/4151 can be connected in several configurations depending on the input voltage, required accuracy, and response time. In all the applications we will see that the input voltage is converted to a current and the circuit will turn the switched current source on at the rate necessary so that the average current from the current source is equal to the input current. As the input voltage (and current) increases, the current source must turn on more often, and the output frequency increases. ‘SELECTING COMPONENTS FOR THE VFC Voltage-to-frequency converters can be used for full scale voltages of 100 mV or greater and full scale frequencies of 1 Hz to 100 kHz. Input voltages in excess of Veg + can be accommodated with appropriate resistor dividers to attenuate the voltages. The following components selection guidelines should be used. 1. Rg should be approximately 14 k2. to optimize the system performance versus temperature. Rs is normally a 12 k fixed resistor and a 5 kM pot to be used to adjust the full scale output frequency. Small variations in Rg have minimal effect on system temperature performance. Incr = Vace/Rg = 1.95 V/Rg 2, Ro Co séts the one-shot pulse width, Ty = 1.1 Ro Co. This pulse width must be shorter than the minimum period of the maximum frequency ie, set it equal to .75 (1/fg). Therefore, Ro Co = .68 (1/fp). Values of Rp should be between 6.8 kM and 680 k0 and Co should be from .001 uF to 1 uF. 3. Rig should be as low as possible for the highest accuracy, (this reduces the effect of current source Royr) but must be large enough to insure that the current source output is greater than Vin max/Rg. Therefore, choose Rg such that Rp ~ 1.33 Viy maxilo. 4. Cg for Figure 2 must be chosen to trade-off between accuracy and response time. Larger val- ues of Cg give greater system accuracy but response time is limited by the Rg Dg time con- stant. A good choice for Dg is 1072/fp. 5. C; for Figures 3 and 4 can be selected depending on the output frequency. The smaller C, is the faster the system response wil be. C, must be large enough to limit the amplifier swing. The op amp will swing a voltage set by IpTo/C;, so if the comparator is biased at 2/3 Voc+ this constrains Cy > 3 IgTo/2 Vec+. A nominal value of C, = 5 x 10~/fy meets this requirement. COMPARISON OF VOLTAGE TO FREQUENCY CIRCUITS Table | shows @ comparison of the three basic circuits set-up for a 0 to 10 V input range and a full scale output of 10 kHz. FREQUENCY TO VOLTAGE CONVERSION The #A7151/4151 can be connected as frequency-to-voltage converter (FVC). This circuit basically works by putting out a current pulse per cycle of input frequency and intergrating the current pulses across an output resistor to give an output voltage which is proportional to the average value of |p (loTofin): S17

FAIRCHILD © 4.A4151 @ 4A7151 PRECISION VOLTAGE TO FREQUENCY CONVERTER FOR NEGATIVE INPUTS ov. ane - “oh 1 Sse seta | | Py |g ewe be TY CU] Ixy | orca Lf je — Ss Fig. 4 a ‘SINGLE SUPPLY FREQUENCY-TO-VOLTAGE CONVERTER wae 10K ce Re vom 2 fs 7 T 00 Kt mousey oy" 0 oourrur mPur (optional) arr pee | WAVE aa [ae DESIGN EQUATIONS. us ~ Fig. 5 PRECISION FREQUENCY TO VOLTAGE CONVERTER: we ~ sa Re = 100.80 vom gl ra" LN tu of “ prey Ty If | raoeeeees bs ees See Fig. 6 5-19

FAIRCHILD @ .A4151 @ 2A7151 LOW COST, REMOTE SENSED 8-BIT A/D CONVERTER ain ~ genn Gov = wo ENEMA wh. Ld “Be away Pony Se ac & to i i wre He vI BE ' . Co> re ~ ame] Fig. 7 a MOTOR SPEED CONTROLLER 15 v sir zat 10k = ° 9] i Beh {> +8¥ Cg a re mE ate BE AY Fig. 8 eo FSK DEMODULATOR

1070 He —_ =

Fig. 9 5-20

Product Information

RC4151TC specifications and overview.

Summary

VOLTAGE-TO-FREQUENCY CONVERTER

Description

VOLTAGE-TO-FREQUENCY CONVERTER

Source title RC4151TC Datasheet(PDF) - Fairchild Semiconductor

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