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Reduced Power Relay Driver - Relays can handle a lot of power. However, for
certain power sensitive designs you would like to reduce the power needed to hold a
relay closed. The circuit below performs such a task. It uses a single
CD4093 quad NAND gate. When the “on” logic input signal is detected, the relay
is first pulsed on for about 500ms. This is sufficient time to insure the relay
is fully closed. After that initial pulse the relay is then driven with a square
wave signal, whose duty cycle can be adjusted. The signal duty cycle can be
adjusted from about 10% to 90%. In most cases a 50% duty cycle will hold the
relay closed. This reduces the average DC current required by the same factor,
which means a 4:1 reduction in power. The circuit can operate over a wide 3v to 15v
range. ….(designed by David A. Johnson) |
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Reference Design for a Powered-Device (PD) Module Based on the MAX5941B PWM
Controller - Maxim App Note 4192 -- 3/04/2008 -- (app note add 5/08)
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Reference Design for the Tas5110dad Digital Audio PWM Power Output Stage - The
true digital audio amplifiers (TDAA) system consists of a PCM–PWM modulator device and
a PWM power output device. The PCM–PWM processor accepts a serial PCM digital audio
stream and converts it to a 3.3-V PWM audio stream. The TDAA output stage provides a
large-signal PWM output. The digital PWM signal....(added 6/06) |
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Servo Pulse to PWM - converter connects an H-Bridge to radio control receivers or
robotic circuits. (added 1/05) |
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Simple circuit allows long PWM soft starts - 02/01/07 EDN-Design Ideas: (design
idea added 05/07) Enhance timing accuracy of a switching regulator's
start-up ramp. |
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Simple Circuit for Driving MicroController Friendly PWM Generators - Microchip
Application Note Published 27-Jun-05 (app note added 2/06) |
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Simple Circuit Provides Efficient PWM - 02/18/99 EDN-Design Ideas: You often need
to control the duty cycle of a square wave. The circuit in Figure 1 works from a
single 5V supply at a frequency of 100 kHz. With minor component changes, you can
configure it for a range of frequencies. The circuit consists of a ramp (sawtooth)oscillator.....(design
idea added 6/03) |
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Simple DC Motor PWM speed control - ….(electronic schematic added 08/08) |
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Simple nanosecond width pulse generator provides high performance - 11/11/04 EDN-Design
Ideas:.....(design idea added 5/05) |
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Simple PWM ADC is Surprisingly Accurate - 06/09/94 EDN-Design Ideas: The reference
voltage in Fig 1a's simple rail-to-rail PWM ADC is the only critical component. The
input-voltage range extends from ground to the power rail which also acts as the
reference. The circuit is essentially a variation on the classic dual-slope
integrator,.....(design idea added 3/03) |
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Speed Error in PWM Fan Control Systems TC646, TC647, TC649 - Microchip Application
Note Published 27-Jul-04 (app note added 2/06) |
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Spice Model & PWM Amplifier Applications Apex-AN33 - Apex App Note (added
08/08/08) |
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Square Wave Modulator has Variable Frequency & Pulse Width - 08/08/02 EDN-Design
Ideas: A few years ago, I worked at a disk-drive company. We had a plating facility
that required square waves to drive the high-voltage plating operation. The challenge
was that the square wave's pulse width had to be variable, along with the duty cycle.
Also, the amplitude of the pulses had to be adjustable.... (added 1/05) |
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Stability & Biasing for PWM Amplifiers Apex-AN41 - Apex App Note (added 08/08/08) |
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Suppressing Acoustic Noise in PWM Fan Speed Control Systems - Microchip
Application Note Published 27-Jul-04 (app note added 2/06) |
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TB085: A Simple Circuit for Driving MicroController Friendly PWM Generators -
Microchip Application Note Published 27-Jun-05 (app note added 2/06) |
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TB093: Multiple PWM Output Soft-Start Controller - Microchip Application Note
Published 29-Nov-05 (app note added 2/06) |
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Timer with 555 - Some useful circuits using the LM555 IC. Scroll to find the Timer
with 555 circuit (11/06) |
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Transistor Pair Lowers PWM IC's Start up Current - 03/18/99 EDN-Design Ideas: An
auxiliary winding usually provides power for the popular UC384X-based offline
switch-mode power supplies (SMPSs). This winding feeds the main PWM controller during
steady-state operation. However, the controller always needs a small start-up current,
which clearly plagues the efficiency in very low-power standby.....(design idea added
6/03) |
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Use a PWM fan Controller in an EMI susceptible circuit - 02/16/06 EDN-Design
Ideas: Control it with either an external negative-temperature-coefficient thermistor
or a PIC microcontroller and its SMBus serial-data bus.....(design idea added 11/06) |
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Using a Function Generator to Create Pulse Width Modulation PWM Waveforms -
Agilent Application Note (added 6/06) |
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Using PWM to Generate Analog Output - Microchip Application Note Published
26-Aug-97 (app note added 2/06) |
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Using the PWM - Microchip Application Note Published 26-Aug-97 (app note
added 2/06) |
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Variable Range PWM A/D for COP820CJ - National Semiconductor Application Note
(app note added 2/06) |
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Variations on the PWM DC Motor Speed Control - (electronic schematic / circuit
added 4/02) |
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Video Design Idea: Leverage PWM output & add a low cost DAC to your system -
07/19/07 EDN-Design Ideas: Bonnie Baker, senior applications engineer at Texas
Instruments and regular EDN columnist, demonstrates a simple way to add DAC
functionality to a microcontroller-based system using only an op amp and two passive
components.....(design idea added 9/08) |
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Wireless RF PWM Dual Motor Controller - (circuit / schematic design added 6/06) |
