Controller gently powers up board capacitors

26th August 2014

Siobhan O'Gorman

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Datasheet

The LTC4231, a quiescent current (IQ) controller which enables safe board or battery insertion and extraction, has been released by Linear Technology. To gently power up 2.7-36V systems, the device controls an external N-channel MOSFET, avoiding sparks, connector damage and system glitches. During normal operation quiescent current is 4µA, dropping to 0.3µA in shutdown mode.

To ensure low current operation, the undervoltage and overvoltage resistive dividers are connected to a strobed ground, lowering their average current draw by 50 times. By controlling back-to-back N-channel MOSFETs, the LTC4231 survives and also protects downstream circuitry from reversed batteries up to -40V. Deep discharge is prevented by undervoltage protection which cuts off low voltage batteries, while oscillations from battery recovery after load removal are avoided by adjustable hysteresis. As well as this, a timed circuit breaker and fast current limit provides dual level overcurrent protection.

The LTC4231 is available in two options: the LTC4231-1 and the LTC4231-2. After an overcurrent fault, the former remains off, while the latter automatically attempts to turn on after a 500ms cooldown period. The controller, which is offered in 12-pin MSOP and 3x3mm QFN packages, operates within 0 to 70°C commercial and -40 to 85°C industrial temperature ranges. Accommodating a wide range of battery chemistries including lead-acid, Li-Ion and stacked NiCd, the LTC4231 is suitable for use with applications that utilise solar power or energy harvesting.1,000-piece pricing starts at $2.25 each.