New Eagle PWM to Analog Converter

Transcription

1 New Eagle P.O. Box #272 Ann Arbor, MI Phone Fax M E C H A T R O N I C C O N T R O L S O L U T I O N S New Eagle PWM to Analog Converter Revision 0.2 PWM2AN /8/2013 New Eagle 3588 Plymouth Road, #272 Ann Arbor, MI (voice) (fax)

2 Features 0-5V analog output that is proportional to PWM duty cycle useful for controllers that cannot read duty cycle (i.e. PWM signals) 3 separate channels Safety feature allows a second input signal (e.g. OEM pedal signal) to pass thru to output if the control module generating PWM signal freezes, shuts down, or loses connection. reverse polarity and ESD protection Wide operating voltage range: 8V 20V Closed Loop Feedback Control Software Library available for improved accuracy Works with Low Side Drive inputs; does not require TTL inputs Description The New Eagle PWM to Analog Converter converts PWM signals to proportional 0-5V analog signals. The converter is especially useful when paired with control modules with PWM outputs but no analog outputs. Safety Pulse Feature The safety pulse feature is intended for vehicle pedal applications. This feature ensures that the original pedal signal (i.e the analog signal from the actual pedal) will pass thru the PWM to Analog box to the OEM ECU unimpeded in the event that the External Control Module (ECM) freezes or loses power. Even though this feature was primarily designed for vehicle pedal applications, a safety pulse signal must be present at the safety pulse input pin (pin 8) for the New Eagle PWM to Analog Converter to function. If no oscillating signal is present at this input pin, the Pass Thru signals (Pins 5, 6, & 7) will be routed through the box to the output pins (Pins 9, 10, 11). If the New Eagle PWM to Analog Converter loses power, then its output will default to the Pass Thru signals as well. Closed Loop Feedback Control Software Library Accuracy is heavily dependent on the design of the particular low side drive. If accuracy is required, close loop feedback is recommended. New Eagle offers a Feedback Control Software library that allows end users to accurately convert PWM signals into analog signals. New Eagle 3588 Plymouth Rd. #272 Ann Arbor, MI (voice) (fax) 2

3 Application Examples Vehicle Pedal Emulation The New Eagle PWM to Analog Converter allows an external control module to command the pedal signal going into the OEM ECU. Control over the pedal signal is a highly desirable feature in dual fuel vehicle conversions, for example. Should the external control module fail or lose power, the safety pulse feature ensures that the original pedal signal (i.e the analog signal from the actual pedal) will pass thru the PWM to Analog box to the OEM ECU unimpeded. The safety pulse feature can also be used to enable and disable pedal interception at any time if the designer so chooses. Aftermarket ECM New Eagle PWM to Analog PWM Output 1 PWM Output 2 PWM Output 3 PWM Signals PWM Input 1 Analog output 1 PWM Input 2 Analog output 2 PWM Input 3 Analog output 3 Foot Pedal Safety Pulse output Safety Pulse Signal Analog Signals OEM ECU Safety Pulse Input Pass Thru 1 Pass Thru 2 Pass Thru 3 Analog signal 1 Analog signal 2 Analog signal 3 Analog Pedal Input 1 Analog Pedal Input 2 Analog Pedal Input 3 Analog Signals Electric Vehicle Conversion One customer has used the New Eagle PWM to Analog Converter in an electric vehicle conversion project. The customer desired to use the OEM fuel gauge on the instrument cluster to display battery State of Charge. The fuel gauge input required an analog signal and the EV control module did not have any analog output channels. The New Eagle PWM to Analog Converter was used to translate a PWM signal (originating from the EV control module) into an analog signal that the fuel gauge could read. ECM New Eagle PWM to Analog Battery SOC PWM Output PWM Signal PWM Input 1 Analog output 1 Analog Signal New Eagle 3588 Plymouth Rd. #272 Ann Arbor, MI (voice) (fax) 3

4 Absolute Maximum Ratings Parameter Min Nom Max Units Supply Voltage 25 V Storage Temperature* C Analog Output Source Current (per channel) <30 ma *These values have not been tested; however according to the specifications for all of the board components, the PWM to Analog board should be able to operate under these conditions. Operating Ratings Parameter Conditions Min Nom Max Units Supply Voltage V Operating Temperature C Total Current Draw 45 ma PWM Input Signal Frequency 1,000 Hz Safety Pulse Frequency Safety Pulse Duty Cycle safety pulse duty cycle = 50% safety pulse frequency=1000hz 100 1,000 10,000 Hz % PWM to Analog Open Loop Offset Error 2 3 % Open Loop Rise Time 3 10% to 90% 160 ms Open Loop Fall Time 3 90% to 10% 155 ms Closed Loop Rise Time 3 10% to 90% 80 ms Closed Loop Fall Time 3 90% to 10% 80 ms 1These values have not been tested; however according to the specifications for all of the board components, the PWM to Analog board should be able to operate under these conditions. 2Open Loop Accuracy is not guaranteed and heavily dependent on the design of the particular low side drive. If accuracy is required, close loop feedback is recommended. 3Within 1% of steady state value New Eagle 3588 Plymouth Rd. #272 Ann Arbor, MI (voice) (fax) 4

5 Duty Cycle(%) Duty Cycle(%) M E C H A T R O N I C C O N T R O L S O L U T I O N S Dynamic Response Open and Closed Loop Response from 90% to 10% Setpoint Open Loop Response Closed Loop Respone time (s) 100 Open and Closed Loop Response from 10% to 90% Setpoint 10 Open Loop Response Closed Loop Respone time (s) New Eagle 3588 Plymouth Rd. #272 Ann Arbor, MI (voice) (fax) 5

6 Connections Pin I/O Name Description 1 Battery Voltage Connects to positive lead of battery with 12V Nominal Voltage 2 Input PWM 1 3 Input PWM 2 4 Input PWM 3 PWM signals from an external control module. Note that these inputs are designed to be driven by a Low Side Drives. 5 Input Pass Thru 1 The signals entering pins 5, 6, & 7 will be passed thru to output pins 6 Input Pass Thru 2 11, 10, 9, respectively, when a safety pulse signal is no longer 7 Input Pass Thru 3 detected on Pin 8. 8 Input Safety Pulse 1000Hz square wave signal sent from an external control module. If the input to pin 8 is not oscillating (e.g. frozen external control module, broken wire, etc.), then signals going into pins 5, 6, & 7 will be passed thru to output pins 11,10, 9, respectively. Note that this input is designed to be driven by a Low Side Drive. 9 Output Analog 3 Pins 9, 10, & 11 output 0V-5V analog signals that are proportional 10 Output Analog 2 to the duty cycle of the PWM signal going into this pins 4, 3, and 2, 11 Output Analog 1 respectively. 12 Ground Connects to chassis ground. Physical Characteristics Parameter Value Units Overall Length 5.24 (133.03) in (mm) Overall Height 1.42 (36.00) in (mm) Overall Width 4.68 (118.8) in (mm) Total Weight (0.213) lb (kg) New Eagle 3588 Plymouth Rd. #272 Ann Arbor, MI (voice) (fax) 6