Ahmad Ayar is an associate member of the technical staff at Maxim Integrated Products Inc., Sunnyvale, Calif. He received a BSEE from San Jose State University, California. Email address: Ahmad_Ayar@maximhq.com
3 results found for Ahmad Ayar , displaying items 1 - 3
June 25, 2009[Ideas For Design] Logic-Level Signals Shifted To Dim -48-V LED Driver
The main source of power in a telecommunications system is -48 V. This source’s negative polarity and its large magnitude with respect to ground pose a challenge when designers want to use low-power ICs in the telecom system’s application circuits. Fortunately, the emergence of high-voltage ICs—with operating voltages of 75 V and higher—has enabled the use of simple biasing techniques in designing circuits for -48-V systems. The technique described here provides...
August 28, 2008[Ideas For Design] Simple PWM Modulator Allows DC Control Signal To Drive LEDs
LED-driver circuits can be dimmed by applying a variable duty cycle (pulse-width modulation, or PWM) to the LED. PWM exploits LED behavior: At higher current levels, the LED’s light output is higher for a given level of power dissipation (temperature). Thus, applying PWM current to the LED yields an average power comparable to that of dc control, but with higher operating current and greater light output. Even if the...
May 12, 2005[Ideas For Design] Single Supply Yields 0- To 5-V Ramp
Using standard circuits and no auxiliary voltage generators (such as charge pumps or inductive dc-dc converters), it's difficult to build a precision, rail-to-rail ramp generator that operates on a single supply and resets to a well-defined level. Figure 1 implements such a circuit using a bootstrapped series reference and an op amp with rail-to-rail I/O and very low bias current. The ramp is generated by a constant charging current into capacitor CRAMP. This is...
