RC4152 FAIRCHILD | Alldatasheet

Document overview

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Technical content

Features

  • Single supply operation
  • Pulse output DTL/TTL/CMOS compatible
  • Programmable scale factor (K)
  • High noise rejection
  • Inherent monotonicity
  • Easily transmittable output
  • Simple full scale trim
  • Single-ended input, referenced to ground
  • V-F or F-V conversion
  • V oltage or current input
  • Wide dynamic range

Applications

  • Precision voltage-to-frequency converters
  • Pulse-width modulators
  • Programmable pulse generators
  • Frequency-to-voltage converters
  • Integrating analog-to-digital converters
  • Long-term analog integrators
  • Signal conversion: – Current-to-Frequency – Temperature-to-Frequency – Pressure-to-Frequency – Capacitance-to-Frequency – Frequency-to-Current
  • Signal isolation: – VFC—opto-isolaton—FVC – ADC with opto-isolation
  • Signal encoding: – FSK modulation/demodulation – Pulse-width modulation
  • Frequency scaling
  • DC motor speed control

Description

The RC4152 is a monolithic circuit containing all of the active components needed to build a complete voltage-to- frequency converter. Circuits that convert a DC voltage to a pulse train can be built by adding a few resistors and capaci- tors to the internal comparator, one-shot, voltage reference, and switched current source. Frequency-to-voltage convert- ers (FVCs) and many other signal conditioning circuits are also easily created using these converters. The RC4151 was the first monolithic VFC available and offers guaranteed temperature and accuracy specifications. The converter is available in a standard 8-pin plastic DIP. Functional Block Diagram 4152-01 4152 4 5 8 -VS Comparator Inputs One Shot Timing Switched Current Source Switched Voltage Reference Voltage Reference Precision One Shot Open Collector Logic Output Transistor Open Loop Comparator Switched Current Source Output Switched Reference Output Open Collector Output Ground RC4152 Voltage-to-Frequency Converters Rev. 1.0.1

PRODUCT SPECIFICATION RC4152 Pin Assignments Pin Descriptions IOUT R S FOUT GND +V S VIN VTH C O5 4152-02 Pin Function

1 Switched Current Source Output (IOUT )

2 Switched Voltage Reference (RS)

3 Logic Output (Open Collector) (FOUT )

4 Ground (GND)

5 One-Shot R, C Timing (C

O )

6 Threshold (V TH )

7 Input Voltage (VlN)

Note: 1. “Absolute maximum ratings” are those beyond which the safety of the device cannot be guaranteed. They are not meant to imply that the device should be operated at these limits. If the device is subjected to the limits in the absolute maximum ratings for extended periods, its reliability may be impaired. The tables of Electrical Characteristics provides conditions for actual device operation. Thermal Characteristics Parameter Min. Typ. Max. Units Supply Voltage +22 V Internal Power Dissipation 500 mW Input Voltage -0.2 +V S V Output Sink Current (Frequency Output) 20 mA Output Short Circuit to Ground Continuous Storage Temperature Range -65 +150 °C Operating Temperature Range RC4152 0 +70 °C RV4152N -25 +85 °C 8-Lead Plastic DIP Small Outline SO-8 Max. Junction Temp. +125 °C +125 °C Max. P D TA<50°C 468 mW 300mW Therm. Res qJC —— Therm. Res qJC 160°C/W 240 °C/W For TA>50°C Derate at 6.25 mW/ °C 4.17mW/ °C

RC4152 PRODUCT SPECIFICATION

Electrical Characteristics

(VS = +15V, and TA = +25°C unless otherwise noted) Notes: 1. Temperature coefficient of output current source (pin 1 output) exclusive of reference voltage drift. 2. Guaranteed but not tested. Parameters Test Conditions Min. Typ. Max. Units Power Supply Requirements (Pin 8) Supply Current V S = +15V 2.5 6.0 mA Supply Voltage +7.0 +15 +18 V Input Comparator (Pins 6 and 7) V OS ±2.0 ±10 mV Input Bias Current -50 -300 nA Input Offset Current ±30 ±100 nA Input Voltage Range 0 VS-2 VS-3 V One Shot (Pin 5) Threshold Voltage 0.65 0.67 0.69 V S Input Bias Current -50 -500 nA Saturation Voltage I = 2.2 mA 0.1 0.5 V Drift of Timing vs. Temperature

2 T = 75 ms over the specified

±30 ±50 ppm/ °C Timing Drift vs. Supply Voltage ±100 ppm/V Switched Current Source (pin 1)1 Output Current R S = 16.7K +138 mA Drift vs. Temperature2 over specified temperature range ±50 ±100 ppm/ °C Drift vs. Supply Voltage 0.10 %/V Leakage Current Off State 1.0 50 nA Compliance Pin 1 = 0V to +10V 1.0 2.5 mA Reference Voltage (Pin 2) V REF 2.0 2.25 2.5 V Drift vs. Temperature2 over specified temperature range ±50 ±100 ppm/ °C Logic output (Pin 3) Saturation Voltage ISINK = 3 mA 0.1 0.5 V ISINK = 10 mA 0.8 V Leakage Current Off State 0.1 1.0 mA Nonlinearity Error (Voltage Sourced Circuit of Figure 3) 1.0 Hz to 10 kHz 0.007 0.05 % Temperature Drift Voltage2 (Voltage Sourced Circuit of Figure 3) FOUT = 10 kHz, over specified temperature range ±75 ±150 ppm/ °C

PRODUCT SPECIFICATION RC4152 Typical Performance Characteristics 1 2345678 9 1 0 +0.01 +0.005 -0.005 -0.01 1 2345678 9 1 0 +0.06 +0.03 -0.03 -0.06 1 2345678 9 1 0 +0.01 +0.005 -0.005 -0.01 1 2345678 9 1 0 VIN (V) +0.10 +0.05 -0.05 -0.10 1 2345678 9 1 0 FIN (kHz) +0.01 +0.005 -0.005 -0.01 1 2345678 9 1 0 4152-03 NL (% Error) +0.12 +0.08 +0.04 -0.04 -0.015 -0.015 -0.015 -0.15 -0.08 -0.09 FIN (kHz) VIN (V) VIN (V)

10 KHz Current-Sourced VFC

Nonlinearity vs. Input Voltage

100 KHz Current-Sourced VFC

Nonlinearity vs. Input Voltage

10 KHz Voltage-Sourced VFC

Nonlinearity vs. Input Voltage

100 KHz Voltage-Sourced VFC

Nonlinearity vs. Input Voltage

10 KHz Precision VFC

Nonlinearity vs. Input Frequency

100 KHz Precision VFC

Nonlinearity vs. Input Frequency VIN (V) NL (% Error) NL (% Error) NL (% Error) NL (% Error) NL (% Error)

voltage-to-frequency converter. components and their interconnection. pin 6, the comparator switches and triggers the one-shot. current source and the open collector output transistor. collector output transistor. the open collector output transistor all will be switched on. the open collector output has transmitted a logic pulse. Figure 1. Single Supply VFC

PRODUCT SPECIFICATION RC4152 The stand-alone voltage-to-frequency converter is one of the simplest applications for the RC4152. This application uses only passive external components to create the least expen- sive VFC circuit (see Figure 1). The positive input voltage V IN is applied to the input com- parator through a low pass filter. The one-shot will fire repet- itively and the switched current source will pump out current pulses of amplitude V REF /RS and duration 1.1 RO C O into the integrator. Because the integrator is tied back to the inverting comparator input, a feedback loop is created. The pulse repe- tition rate will increase until the average voltage on the inte- grator is equal to the DC input voltage at pin 7. The average voltage at pin 6 is proportional to the output frequency because the amount of charge in each current pulse is precisely controlled. Because the one-shot firing frequency is the same as the open collector output frequency, the output frequency is directly proportional to V IN. The external passive components set the scale factor. For best linearity, RS should be limited to a range of 12 kW to 20 kW The reference voltage is nominally 2.25V for the RC4152. Recommended values for different operating frequencies are shown in the table below. The single supply VFC is recommended for uses where dynamic range of the input is limited, and the input does not reach 0V . With 10 kHz values, nonlinearity will be less than 1.0% for a 10 mV to 10V input range, and response time will be about 135 ms. Precision Current Sourced VFC This circuit operates similarly to the single supply VFC, except that the passive R-C integrator has been replaced by an active op amp integrator. This increases the dynamic range down to 0V , improves the response time, and eliminates the nonlinearity error introduced by the limited compliance of the switched current source output. The integrator algebraically sums the positive current pulses from the switched current source with the current V IN/RB . To operate correctly, the input voltage must be negative, so that when the circuit is balanced, the two currents cancel. By rearranging and substituting, Recommended component values for different operating frequencies are shown in the table below. The graphs shown under Typical Performance Characteris- tics show nonlinearity versus input voltage for the precision current sourced VFC. The best linearity is achieved by using an op amp having greater than 1.0 V/ms slew rate, but any op amp can be used. Precision Voltage Sourced VFC This circuit is identical to the current sourced VFC, except that the current pulses into the integrator are derived directly from the switched voltage reference. This improves tempera- ture drift at the expense of high frequency linearity. The switched current source (pin 1) output has been tied to ground, and RS has been put in series between the switched voltage reference (pin 2) and the summing node of the op amp. This eliminates temperature drift associated with the switched current source. The graphs under the Typical Performance Characteristics show that the nonlinearity error is worse at high frequency, when compared with the current sourced circuit. Single Supply FVC A frequency-to-voltage converter performs the exact oppo- site of the VFCs function; it converts an input pulse train into an average output voltage. Incoming pulses trigger the input comparator and fire the one-shot. The one-shot then dumps a charge into the output integrator. The voltage on the integra- tor becomes a varying DC voltage proportional to the frequency of the input signal. Figure 4 shows a complete single supply FVC. Operating Range R O C O R B C B DC to 1.0 kHz 6.8 k W 0.1 mF 100 k W 10 mF DC to 10 kHz 6.8 k W 0.01 mF 100 k W 10 mF DC to 100 kHz 6.8 k W 0.001 mF 100 k W 10 mF Range Input VIN Output FO Scale Factor R O CO CI RB 0 to -10V 0 to 10 kHz 1.0 KHz/V 6.8 kW 0.01 mF 0.005 mF 100 kW 0 to -10V 0 to 100 kHz 10 KHz/V 6.8 kW 0.001 mF 500 pF 100 kW T 1 FOUT V IN R B T P IOUT V REF R S FOUT V IN V REF R S R B 1.1RO C O

Figure 2. Precision Current Sourced VFC Figure 3. Precision Voltage Sourced VFC

0 F 10kHz

various operating ranges are shown in the following table. ing integrator, causing the output voltage to be negative. Figure 4. Single Supply FVC

0 F 10kHzIN

RC4152 PRODUCT SPECIFICATION 4152-08 S TH P-P B Z Frequency Input W OUT IN +15V 10 k R 6.8 k 10 k F 5.0 V Squarewave 10 k 5 k +15V 0.022 F V V +V I Gnd F R C

4152 VFC

C 5 pF 100 R 100 k V Voltage Output -10V V 0R 10 k +VS Offset Adjust R 100 k C 0.01 F O m m S O W O W W W IN I OUT B W W W W O R = 16.7KS O 7 5 218 CIN +V S -VS

PRODUCT SPECIFICATION RC4152 Schematic Diagram +VS (8) Q36 Q37 Q35 Q33 Q34 3.6K IOUT (1) R S (2) Q28 15K Q41 Q27 Q26 7.8K Q25 Q4Q3Q2 (6) VTH INV (7) Q5 Q6 Q7 Q8 2K Q9 Q10 Q11 Q21 Q22 Q23 Q17 Q16 Q18 Q12 Q13 (5) C O Q14 Q19 Q20 Gnd (4) 10K 10K 10K -VS Q15 12K D39 D43 Q42 Q38 Q40 W V UTX (3) FoUT Q32 D29 6.3V SRYNZM 4152-09 Q30 6.2K

RC4152 PRODUCT SPECIFICATION Notes:

PRODUCT SPECIFICATION RC4152 6/25/98 0.0m 003 Stock#DS30004152 Ó 1998 Fairchild Semiconductor Corporation LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com

Ordering Information

Notes: N = 8-lead plastic DIP M = 8-lead plastic SOIC Part Number Package Operating Temperature Range RC4152N N 0 °C to +70°C RC4152M M 0 °C to 70°C RV4152N N -25 °C to +85°C