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June 1999
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CA3228
Control System with Memory
Features
* Low Power Dissipation * I L Control Logic * Power-On Reset * On-Chip Oscillator for System Time Reference * Single Input Line for Operator Commands * Amplitude Encoded Control Signals * Transient Compensated Input Commands * Controlled Acceleration Mode * Internal Redundant Brake and Low-Speed Disable * Braking Disable
2
Description
The CA3228 is a monolithic integrated circuit designed as an automotive speed-control system. The system monitors vehicle speed and compares it to a stored reference speed. Any deviation in vehicle speed causes a servo mechanism to open or close the engine throttle as required to eliminate the speed error. The reference speed, set by the driver, is stored in a 9-bit counter. The reference speed can be altered by the ACCEL and COAST driver commands. The ACCEL command causes the vehicle to accelerate at a controlled rate; the COAST command disables the servo, thereby forcing the vehicle to slowdown. Application of the brake disables the servo and places the system in the standby mode while the RESUME command returns the vehicle to the last stored speed. Vehicle speed and driver commands are inputs to the integrated circuit via external sensors. Actuators are needed to convert the output signals into the mechanical action necessary to control vehicle speed. The CA3228 is supplied in a 24 lead dual-in-line plastic package (E suffix). Refer to AN7326 for application information.
Applications
* Automotive Speed Control * Residential and Industrial Heating and Cooling Controls * Industrial AC and DC Motor Speed Control * Applications Requiring Acceleration and Deceleration Control
Pinout
CA3228 (PDIP) TOP VIEW
Ordering Information
PART NUMBER CA3228E
GND NC 1 2 3 4 5 6 7 8 9 24 GND 23 OUTPUT GATE 22 VACUUM CONTROL 21 VENT CONTROL 20 CONTROL AMP+ 19 CONTROL AMP OUTPUT 18 CONTROL AMP17 ALIGN 16 V ERROR 15 ACCELERATE CAPACITOR 14 ACCELERATE RESISTOR 13 VCC
TEMPERATURE -40oC to +85oC
PACKAGE 24 Lead Plastic DIP
DRIVER COMMAND COMMAND DELAY OSCILLATOR V MEMORY CURRENT SENSE SPEED SENSOR INPUT F/V OUT
F/V FILTER 10 VS 11
BRAKE INPUT 12
CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper I.C. Handling Procedures. Copyright
(c) Harris Corporation 1999
File Number
1436.3
10-31
Specifications CA3228
Absolute Maximum Ratings
Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +9.0V Supply Current, ICC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30mA Driver Command Input (ICMD), Pin 3 . . . . . . . . . . . . . . . . . . . . 2mA Brake Input (IBRAKE), Pin 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . 2mA Storage Temperature Range . . . . . . . . . . . . . . . . -65oC to +150oC Maximum Junction Temperature. . . . . . . . . . . . . . . . . . . . . +150oC
Thermal Information
Thermal Resistance JA Plastic DIP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65oC/W Power Dissipation Per Package For TA = -40oC to +70oC . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2mW For TA Above +70oC . . . . . . . . . . . Derate Linearly at 15.4mW/oC Lead Temperature (Soldering 10s) . . . . . . . . . . . . . . . . . . . +265oC Operating Temperature Range . . . . . . . . . . . . . . . . -40oC to +85oC
CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
Typical Switching Characteristics
Driver Command Input Hold Times (Based on 0.68F on Pin 4): ACCEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50ms COAST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50ms RESUME. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330ms ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50ms OFF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50ms Internal Oscillator Frequency, FOSC . . . . . . . . . . . . . . . . . . . 10kHz (Based on 0.001F at Pin 5)
System Performance FOSC = 50kHz, fS/Speed Ratio = 2.22Hz/mph
Speed Sensor Input Frequency Range, fS at Pin 8 . .62Hz to 222Hz Speed Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.45 mph Minimum Operating Speed. . . . . . . . . . . . . . . . . . . . . . . . . . 25 mph Maximum Stored Speed . . . . . . . . . . . . . . . . . . . . . . . . . . 100 mph Redundant Brake Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 mph
Electrical Specifications
PARAMETERS Operating Voltage
TA = +25oC, VCC = 8.20V, Unless Otherwise Specified (Refer to Figures 2 and 3) SYMBOLS VCC TEST PIN 13 T.P.B. ICC V7 V17 V3IDLE 13 7 17 3 43k to Ground 41k to Ground S1, S2, S3, S4, S5 Open S2 Closed S3 Closed S4 Closed S5 Closed S1 Closed S6 Closed 62Hz fS 222Hz TEST CONDITIONS MIN 7.40 3.50 7.50 4.85 4.00 7.6 MAX 9.00 15.0 30.0 5.95 4.20 7.9 UNITS V Vpp mA V V V
Speed Sensor Input Voltage Amplitude VCC Supply Current Current Sense Voltage Align Voltage Command Idle Voltage
RESUME Command Voltage ACCEL Command Voltage COAST Command Voltage OFF Voltage ON Voltage Brake Input Voltage OUTPUT VOTLAGE Gate
V3RES V3ACCEL V3COAST V3OFF V3ON VBRAKE
3 3 3 3 T.P.A. 12
5.95 3.95 1.22 0 9.2 5.4
6.56 4.91 2.23 0.77 28 28
V V V V V V
VOL VOH
23
4.7k to VCC
8
300 400 400 -
mV V mV V mV V
VAC
VOL VOH
22
1.2k to VCC
8
VENT
VOL VOH
21
1.2k to VCC
8
10-32
Specifications CA3228
Electrical Specifications
PARAMETERS Memory Set Error Deadband Range (VAC and VENT Outputs Off) Control Amplifier Gain D/A Voltage Range TA = +25oC, VCC = 8.20V, Unless Otherwise Specified (Refer to Figures 2 and 3) (Continued) SYMBOLS V6 - V10 VDB TEST PIN 6, 10 21, 22 Sweep Pin 19, Voltage at 1V/sec ACNTL = V19/V16 Set Mode TEST CONDITIONS MIN -77 0.96 MAX 67 1.43 UNITS mV V
ACNTL VM
16, 19 6
74 6
7.50
Ratio V
Functional Block Diagram
1 GROUND 24 VCC 3 VCC RESUME DRIVER COMMAND COMMAND DELAY 3 4 COMMAND DECODER AND DELAY ACCEL COAST ON OFF TOGL I2 L CONTROL LOGIC GATE
OUTPUT 23 GATE 21 VENT CONTROL VACUUM 22 CONTROL 19 CONTROL AMP. OUTPUT
VENT
VAC
OSCILLATOR
5
OSC. OVER SPEED DETECTOR RESUME DETECTOR +
BRAKE INPUT 12
BRAKE SENSOR
20 CONTROL AMP. (+) CONTROL AMP. _ ERROR AMP. 18 CONTROL AMP. (-) 16 0.45V "E" ACCEL. RATE AMP 14 ACCELERATE RESISTOR V ERROR
SPEED SENSOR INPUT F/V OUT
8 9 F/V CONVERTER
VS
MINIMUM SPEED SENSOR
REDUNDANT BRAKE
F/V FILTER 10 VS ANALOG TO DIGITAL TO ANALOG CONVERTER VM "C" "B" MODE SW "D" "A"
VS 11
15 ACCELERATE CAPACITOR
V MEMORY CURRENT SENSE
6
VM ALIGN 17 ALIGN
7
CURRENT SENSE
10-33
CA3228
START
ERASE MEMORY YES NO BRAKE? NO OFF > 40 ms? NO IGNITION OFF? YES
NO
ON > 40 ms? YES STANDBY
NO COAST? YES NO > 25MPH? YES INPUT > 40ms? > 25MPH? YES INPUT > 40ms? YES ACCEL? YES
NO RESUME? YES ACCEL > 4 ms? YES COAST > 40ms? YES
NO
NO
NO
NO > 2 MPH? RELAX SERVO ACCEL AT CONTROLLED RATE RELAX SERVO > 25MPH? YES > 25MPH STORED? STILL COAST? NO ENABLE SERVO ENABLE SERVO DISABLE RESUME MODE YES YES STILL ACCEL? NO YES 2 INPUT > 245ms? YES NO NO
YES
STORE PRESENT SPEED
SPEED = STORE? NO
NO CRUISE
SPEED < STORE? YES
YES
COAST >40ms? NO YES
RELAX SERVO
ACCEL AT CONTROLLED RATE
1
ACCEL > 40ms? NO NO YES
DISABLE RESUME MODE
YES ACCEL > 40ms? NO
YES IGNITION OFF? > 25MPH? NO YES Redundant BRAKE? NO NO 2 1
DISABLE RESUME MODE
YES COAST > 40ms? NO
DISABLE RESUME MODE
YES BRAKE?
NO YES YES CLUTCH DISABLE? NO
YES
OFF > 40ms?
BRAKE NO NO CLUTCH DISABLE? YES
10-34
CA3228
V3ON ON R3, 2.2K RESUME R4,680 SET/ACCEL R5, 120 COAST OFF
MOMENTARY CONTACT DRIVER COMMAND SWITCHES S1 S2 S3
VCC T.P.A. RI 560 R2 10K 0.001F 8.2K 10K 0.68F 1 0.1F 2 3 CA3228E 4 5 6 7 43K 0.047F 8 9 10 150K 11 12 51K BRAKE LIGHT BRAKE SWITCH S6 SWITCH FUNCTION S1 - ON S2 - RESUME 24 23 22 21 20 19 18 17 16 15 14 13 2.4M REXT VCC VOLTAGE AT TERM. 3 RATIO TO VCC MIN 1.12 0.725 0.482 0.148 0 0.93 MAX 0.8 0.599 0.272 0.094 0.96 10K CEXT 2.2F + 10K 1M GATE VAC VENT VCC 10K
SEE FIGURE 3
S4 S5 0.05F
N T.P.B. S SPEED INPUT FREQUENCY, fS 2.22 Hz/MPH
2.2F 10K
ALL RESISTANCE VALUES ARE IN OHMS
VBRAKE
S3 - ACCEL S4 - COAST S5 - OFF IDLE (Note 1)
NOTE: 1. All Switches Open FIGURE 2. TYPICAL AUTOMOTIVE SPEED CONTROL APPLICATION
0.22F
+8.2V
VOLT. REG
+14.4V
1.2K VCC VAC
1.2K
VENT SOLENOID
VENT CA3228E (SEE FIGURE 2) 4.7K GATE 620 0.5W
VACUUM SOLENOID
TO AIR N.O. VENT VALVE N.C. VAC VALVE
TO VACUUM SOURCE
DIAPHRAGM
SYSTEM MODE VALVE
POSITON FEED BACK (OPTIONAL TO PIN 20)
ACCEL Open Close
CRUISE NC (Note 1) Close (Note 1)
COAST NC NC
VAC VENT
NOTE: 1. Open or Closed as Required to Maintain Set Speed Error
TO THROTTLE
ACCEL VAC (Pin 22) VENT (Pin 21) GATE (pin 23) H H L
CRUISE L H L
COAST L L L
BRAKE L L H
REDUNDANT BRAKE L L H
HI-SPEED DROPOUT L L H
LO-SPEED DROPOUT L L H
FIGURE 3. SOLENOID DRIVERS AND SERVO VACUUM CONTROL MECHANISM TYPICAL APPLICATION
10-35
CA3228 Device Description and Operation
The functional block diagram and Figures 1, 2 show the speed- control flow chart, and a typical automotive speedcontrol application, respectively. Command Decoder and Delay Logics (Pins 3,4) Driver commands are input to pin 3 through the Driver Command Line. These signals are encoded on a single line as voltage levels selected by switches which adjust a resistor divider network. The voltage level established is compared to a reference level which decodes the command. A command level greater than VCC + 0.8V turns the system On, enabling dynamic control. Once the system is enabled, a voltage level of 0.88VCC, 0.66VCC, and 0.38VCC decodes the RESUME, ACCEL, and COAST command, respectively. A driver command of 0.12VCC or less turns the system Off. The Driver Command Delay established by the current sources and a capacitor at pin 4 assures that ON, OFF, ACCEL, and COAST commands are considered valid only if longer than 50ms. The time for RESUME is 330ms. Control Logic The Control Logic accepts signals from the command decoder and other sensors. It causes the memory to be updated when operating in ACCEL and COAST modes. It will put the system in Standby mode if brakes are applied, if the speed error exceeds 11mph, or if the vehicle speed drops below the minimum Speed Lockout (25mph). It will return the vehicle to the previous set memory speed when a RESUME command is given. Frequency to Voltage Converter (Pins 8-11) The speed sensor input fS at pin 8 is an AC signal whose frequency is directly proportional to the vehicle speed at approximately 2.22Hz/mph The current sources, capacitor and comparators at pin 9 cause equal rise and fall times to occur at pin 9 on the positive- and negative-going slopes of the sensor input. Pulse currents of time duration equal to the rise and fall times are used to charge the parallel resistor capacitor combination at pin 10 to give a voltage (VS) at pin 10 proportional to frequency at approximately 27mV/Hz. The fS frequency range may be altered by changing the values of the filter capacitors at pins 8 and 9. However, the maximumto-minimum frequency ratio will remain fixed.
MEMORY VOLTAGE, VM (V) -40oC 6 5 4 3 2 1 0 0 50 100 150 200 FREQUENCY, fS (Hz) +85oC +25oC
FREQUENCY
Memory Voltage, VM (Pin 6) Upon release of the ACCEL or COAST switches the voltage, representing vehicle speed VS determined by the output from the frequency-to-voltage converter, is stored as a binary number in a 9 bit counter. A memory update comparator allows clocking of the counter until memory voltage VM equals VS. The output of the counter controls a ladder network which provides memory voltage VM at pin 6. Analog Accelerate and Resume Generator (Pins 14,15) Numerous functions are combined in what is called the Analog Accelerate and Resume Generator. The circuit switches the signal output at pin 15 depending on the mode of operation. In the Accelerate and Resume mode the capacitor at pin 15 is charged at a fixed rate [450mV/(REXT) (CEXT)]. In the Cruise mode pin 15 follows the memory voltage (VM) and in the On, Off, Brake, Redundant Brake, Minimum Speed Lockout, and Coast modes, pin 15 follows the voltage representing vehicle speed (VS).
-40oC 6 5 4 3 2 1 0 0 -40oC 50 100 150 FREQUENCY, fS (Hz) 200 250 +85oC +25oC
FIGURE 5. TYPICAL CHARACTERISTIC F/V CONVERTER OUTPUT, VS vs FREQUENCY
Error Amplifier (Pin 16) In the Cruise mode the Error Amplifier determines the difference between the set memory speed (VM) and the actual speed (VS). This error signal is fed to the control amplifier where it defines whether VAC or VENT is required. The error signal represents deviation in vehicle speed from the memory or set speed condition. The Error signal is also used to control the Redundant Brake feature. Redundant Brake Comparator When the error output drops below approximately 0.42VCC, the Redundant Brake output is activated. Redundant Brake causes the chip to go into the Standby mode. Control Amplifier (Pins 18, 20) The Control Amplifier is an op amp using external components to set the gain. Inputs to the Control Amplifier are from the Error Amplifier output, servo position sensor and align output. The output of the Control Amplifier controls the VAC and VENT outputs. VAC, VENT and Gate-Driver Outputs (Pins 21, 22, 23) The VAC, VENT and Gate Outputs are open collector devices used to control the throttle position. For the system
FIGURE 4. TYPICAL D/A MEMORY VOLTAGE, VM vs
10-36
MEMORY VOLTAGE, VM (V)
CA3228
to be able to supply vacuum, the gate output must be low. If the output from the Control Amplifier exceeds 0.573VCC, vacuum is supplied to the servo unit. If the output of the Control Amplifier is between 0.573VCC and 0.427VCC the vacuum is held in the servo unit and vehicle speed is maintained. If the output from the Control Amplifier drops below 0.427VCC or if the gate output is high, the servo unit vacuum is vented. Overspeed Detector Comparator The Overspeed Detector circuit is used when the following sequence of events occur: A speed is set in memory, the vehicle is manually accelerated (foot pedal) to a higher speed and then the ACCEL switch is activated. During vehicle acceleration VS voltage is greater than the VM voltage into the memory update comparator. When the ACCEL command is given, the capacitor at pin 15 rapidly charges to within 60mV of VS before switching the comparator output low and starting the fixed acceleration rate from the present vehicle speed. The 60mV of offset is required to insure that the output of the overspeed detector is low under normal operating conditions. Hysteresis is also designed into the comparator to eliminate noise problems which may prevent the chip from going into the Acceleration mode. End of Resume Comparator The Resume Comparator is used when the following sequence of events occurs: A speed is set in memory, the brake applied, causing the vehicle to go to a lower speed, and the RESUME switch is activated. Activation of the RESUME switch causes a fixed acceleration rate from the lower speed until the capacitor voltage at pin 15 is equal to the VM voltage. A filter circuit contained in the output of the resume comparator insures that noise doesn't reset the comparator until VPIN actually equals VM. Align Voltage Source (Pin 17) The Align Voltage Source is a X1 buffer with an output of 0.5VCC. Brake Input Comparator (Pin 12) When the Brake Input exceeds 0.55VCC, the chip will go into the Standby mode from Cruise. Minimum Speed Lockout Assures that the system remains in a Standby mode if vehicle speed VS is below 0.183VCC. It causes the system to revert to the Standby mode if VS drops below 0.183VCC in the Cruise mode. Digital Filter for Redundant Brake and Minimum Speed Lockout A 4 bit shift register with an all `1's output decode is used to filter transients and electromagnetic interference. The filter prevents false signals from putting the system into Standby from Cruise. Ramp Oscillator (Pin 5) The Ramp Oscillator at pin 5 nominally varies between amplitudes of 4.1V and 6.1V. The discharge rate is approximately 4X the charge rate. With a capacitor of 0.001F on pin 5, the nominal oscillator frequency is 50kHz.
10-37
CA3228
DVR CMD Q38 Q38 + A
3
RESUME I17 147 ON/OFF 13 Q4 ON ACTIVE HIGH V'S Q188 MSLT I113 B
VCC
16
12 V
Q1 CC 2 V BE Q8 +
--------- + 15 RESUME Q36 Q35 + I17 0.879 VCC ENABLE Q26 Q32 + I25 0.661 VCC ACCEL Q31 COAST Q30 + I23 0.376 VCC ENABLE 18 10
-
Q284
79
Q185 + ACT HI 0.183 VCC MIN SP LOCKOUT ACT Q203 LO Q207 + ACT HI
-
62 66
80
67 C QSC 63 (5) 69
ER 0.43 VCC
-
I135 I136 I58 4 BIT SR D I42 I35 I50 I51 92
REDUNDANT BRAKE
5
9
11 COMMAND DELAY TIME GEN.
I146
ALL 1'S DECODE
8
4 CMD 4 DELAY
V
Q8
CC -------2
Q7 +
-
I3 2 65 ACCEL E COAST
Q26 Q27 + I21 0.121 OFF VCC
1
F 89 90 BRK INPUT 12 0.55 VCC Q141 Q136 + ACT HI 81 I142 91 H
ON/OFF
G
-
FIGURE 6. FUNCTIONAL BLOCK DIAGRAM FOR SPEED CONTROL (Continued On Next Page)
10-38
Q276 A/D BUF Q268 Q276 Q278 I141 OSC (1) 70 72 73 Q279 75, 76, 77 MEM UPDATE
+ -
Q269 BUFFER AND LEVEL SHIFT
VM ON/OFF ACTIVE LOW 71 105 120 DQ I121 OSC (3) 123 OSC (2) 106 107 113 111 OSC (3) 108 109 110 104
A D/A CLOCK
122
I125
B
84
OSC
OSC OSC
OSC (4) Q I145 85 112 86 OSC (3) 117 115 AC + MSLT Q232 A/D "A"
+
I128 118 119
C
AC + MSLT 114
5
68 + TO A IN CRUISE ACTIVE LOW 95 98 99 XI + Q258 VBE ACCEL 14 RESISTOR XI Q251 Q242 15 ACCEL CAP. 15 Q174 22
+ +
D/A CLEAR 9 BIT D/A Q1
D/A CLOCK
94 100 Q257 450MV
Q9
D VSS Q231"B" OPEN DURING ACC, RES RAMP ACTIVE HIGH "D" 102 + TO B IN ON, OFF, BRAKE, COAST ACTIVE LOW 101 VAC 60MV ACT HI VENT Q212 I138 21 ACT LO GATE Q157 Q156 96 CONTROL AMP ACT LO Q177 Q178 23
+ +
93
OPEN POSITION DURING SET ACCEL AND RESUME
A/D VM 6
CA3228
Q174
FIGURE 6. FUNCTIONAL BLOCK DIAGRAM FOR SPEED CONTROL (Continued)
10-39
0.573 Q168 VCC Q171
+
OVER SPEED DET. Q213
ER ERROR AMP Q201 Q196
+
+ -
Q161
16 Q200 V ERROR
13 VCC
103
Q166 0.427 Q167 VCC + VCC 19 CONTROL AMP OUTPUT Q179
CONTROL 18 AMP (-) 20 CONTROL AMP (+) VCC /2
97
E F Q216
ACTIVE ACCEL CLAMP
DC BIAS
7 CURRENT SENSE
G Q225 + Q228 RESUME COMP 2I
+
88 1 AC + MSLT I/2 Q111 + Q118 Q117 Q112 COMP
+
H
24 GND 87 X1 BUF Q277 Q121 Q119 10 Q277 Q271 BUF F/V FILTER Q122 11 VS
Q98 COMP AND CLAMP +
-
V
X1
8 Q125 0.482 Q114 VCC Q113 I
CC --------2
Q270 V'S VS S BUFFER AND LEVEL SHIFT
+
17 ALIGN
SENSOR INPUT
AMPL AND LIMITER
+ -
F/V
9
Q105 0.012 Q110 VCC

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