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Car contact monitors, level shifters draw miniscule power

Posted: 26 Dec 2007 ?? ?Print Version ?Bookmark and Share

Keywords:car contact monitors? level shifters? power draw?

Maxim Integrated Products has introduced the MAX13037/MAX13038 automotive contact monitors and level shifters with an integrated voltage regulator, watchdog timer and reset functions. These devices monitor and debounce eight remote mechanical switches while consuming 28?A (typ) supply current. To achieve this low current consumption, they make use of programmable polling periods and a programmable scanning period. Providing a wide input-voltage range (45V), high ESD protection (8kV on switch inputs), adjustable wetting current and an LDO, the MAX13037/MAX13038 are suitable for harsh automotive environments such as body controller applications.

To minimize the ECU's overall current consumption, the MAX13037/MAX13038 feature an open-drain interrupt output that is active in the absence of a logic supply and can be used to wake up an external MCU from a sleep state. Additionally, any of the switch inputs can be prohibited from asserting an interrupt by writing to the appropriate register through the SPI-compatible interface. The SPI interface eases programming, and is used to read the switch status and configure the operating characteristics of each device. The high modularity of the MAX13037/MAX13038 minimizes external component count and allows multiple devices to be cascaded to monitor/configure additional switches.

The MAX13037/MAX13038 provide a complete solution for mechanical switch interfacing. All eight switch inputs feature programmable wetting current and switching hysteresis. Four inputs are for ground-connected switches, and the other four inputs can be programmed in groups of two as battery- or ground-connected switches. In addition, the microcontroller interface pins can be configured to have direct level-shifting outputs for interfacing with PWM, low-voltage, or other timing signals.

The MAX13037/MAX13038 operate from a 6V to 26V battery voltage and withstand a 42V load-dump. A separate 2.7V to 5.5V logic-supply input sets the interface voltage. The MAX13037 features a 5V LDO regulator, and the MAX13038 features a 3.3V LDO regulator. Both LDOs are capable of providing up to 150mA.

The MAX13037/MAX13038 are available in a Pb-free, RoHS-compliant, 6mm x 6mm, 36-pin TQFN package, and are fully specified over the -40C to 125C automotive temperature range. Prices start at $2.16 (1,000-up, FOB USA).

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