Multi-output power IC powers automotive tasks

Three-channel current-mode PWM step-down DC/DC convertor IC delivers up to 2.4A from its primary output and up to 1.5A from the other two plus a fourth LDO output.

New from Linear Technology, the LT3507 is a triple-channel current-mode PWM step-down DC/DC convertor with three internal 36V power switches and an LDO controller, all packaged in a 38-lead 5 x 7mm QFN package.

One channel is capable of delivering up to 2.4A of output current while the other two switching regulators can deliver 1.5A of continuous output current.

Additionally, an integrated LDO controller combined with an external transistor can be connected to the output of any of the switching regulators or can be run directly from the input voltage, offering a fourth low noise channel.

Its wide input range of 4 to 36V makes it ideal for regulating power from a wide variety of sources from fixed input rails, 24V industrial supplies and automotive batteries.

As each switching regulator has its own input pin, up to three different voltage rails can drive the LT3507, offering maximum efficiency for each channel.

For automotive applications, the LT3507's minimum input voltage of 4V enables it to meet the low input voltage requirements for automotive cold crank conditions.

Similarly, its 36V input capability enables it to withstand transients commonly found in load-dump scenarios.

The LT3507's 250kHz to 2.5MHz switching frequency is user programmable, enabling it to maximise efficiency while avoiding critical frequency bands such as AM radio bands in automotive applications.

Its high frequency operation also enables the use of tiny, low cost inductors and ceramic capacitors, resulting in low, predictable output ripple.

The LT3507's low-saturation-voltage (400mV at 2A and 350mV at 1.5A) internal switches offer efficiencies of up 88%, eliminating the need for external heatsinking.

All three of the LT3507's convertors are synchronised to either a common external clock input or its internal oscillator.

The 2.4A channel maintains a 180-degree phase offset between the two 1.5A channels to reduce input ripple current.

An internal 0.80V reference enables sub-1V output voltages required to power the latest generation of low voltage DSPs and microcontrollers.

Independent run, tracking/soft-start and power-good indicators ease supply sequencing.

Other features include cascadability and user programmable overvoltage and undervoltage lockouts.

The low-current (below 1uA) shutdown provides extended run-time in battery-powered systems.

The LT3507EUHF is available from stock in a 5 x 7mm QFN-38.

Pricing starts at US $4.25 each in 1000-piece quantities the LT3507IUHF industrial temperature I-grade (-40 to +125C), version and the LT3507HUHF automotive H-grade (-40 to +150C) version are available from stock.

Pricing starts at US $5.10 and $5.35, respectively, in 1000-piece quantities.

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