DALLAS Dallas Semiconductor's 5- and 3.3-V MicroMonitors, the DS1814 and DS1819, are full-function CPU supervisors with a redesigned band-gap reference that is said to cut current consumption by roughly one-fourth over other bandgap products.
Product manager Jerry Miller explained that CPU supervisors automatically stop, start or hold up the CPU in response to power changes, external overrides and software-execution status. They can be used in any system with a microprocessor or microcontroller but are particularly helpful in small, battery-powered devices, such as cell phones, in which power and space savings are critical. The devices are available in SOT-23-5 packages and consume 15 microamps of quiescent current.
The DS1814 monitors a 5-V supply with options for 5 or 10 percent tolerances. The DS1819 monitors a 3.3-V supply with options for 5, 10 or 20 percent tolerances. Both have a precision temperature-compensated reference, comparator, oscillator and clock chain. When power input falls below a programmed tolerance, the reset output activates and remains active for at least 140 ms after the voltage returns to an in-tolerance condition.
The DS1814 and DS1819 are available in three versions compatible with Maxim's MAX823/4/5. Each provides an active-low power-on reset and two of these three functions: active-high reset output, pushbutton reset and watchdog. The pushbutton reset control supplies a minimum 140-ms reset pulsewidth before full operations resume. The watchdog timer function, which can be optionally disabled, issues a reset if no activity is seen on the strobe input within 1.12 seconds.
The MicroMonitors are available now at 72 cents each in quantities of 1,000.
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EETInfo No. 607