Sunnyvale, Calif.—Maxim Integrated Products' MAX6877-MAX6883 are dual/triple power-supply
trackers/sequencers for controlling power-up and power-down of up to three rails. They're the company's first hardware programmable (versus programmable memory) trackers and sequencers for cost-effective design in simplified power management systems. Users adjust key performance parameters such as voltage thresholds, slew rates, and timing parameters with (external) resistors and capacitors.
The MAX6877/MAX6878/MAX6879 will track or sequence voltages; the MAX6880-MAX6883 are sequencers. The MAX6877, 6880, and 6881 are three-rail devices; the MAX6878, MAX6879, MAX6882, and MAX6883 are two-rail devices.
In the sequence mode, these controllers turn on their (external) MOSFETs in step, with the delay between each rail set by a capacitor. In track mode, the gate of each MOSFET is continuously adjusted in a closed-loop control system to ensure that the voltage track is within 125 mV of the reference ramp. If any of the voltages fails to sequence or track within specifications, the chip asserts a fault condition and all MOSFETs are turned off. Internal 100-ohm pulldown circuitry is activated to help discharge the capacitance at the output.
All devices feature a capacitor-adjustable slew-rate input that controls the ramp rate at each output. Other features include a margin disable input, an enable input, and a power-good output. The MAX6877, 6878, and 6879 also feature latch-off and an auto-retry mode if the supplies fail to come up.
Preliminary datasheets for these products are available by clicking here for the MAX6877 and here for the MAX6880. The MAX6877-MAX6883 devices are available in 4-by-4 mm, 16- or 24-pin TQFN packages and are fully specified from -40 to +85°C. Prices start at $2.47 each (1000-up, FOB USA). Evaluation kits are available to simplify design.
Maxim Integrated Products, 1-800-998-8800, www.maxim-ic.com