Milpitas, Calif. Linear Technology has introduced the LT3507, a triple-channel current mode PWM step-down dc/dc converter with three internal 36-V power switches and a LDO controller, all packaged in a 38-lead, 5 x 7-mm QFN package. One channel is capable of delivering up to 2.4 A of output current while the other two switching regulators can deliver 1.5 A of continuous output current.
The wide input range of 4 V to 36 V makes the LT3507 suitable for regulating power from a wide variety of sources including fixed input rails, 24-V 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. In addition, an integrated LDO controller combined with an external transistor can be connected to VOUT of any of the switching regulators or can be run directly from the input voltage, offering a fourth low noise channel.
For automotive applications, the step-down converter's minimum input voltage of 4 V enables it to meet the low input voltage requirements for automotive cold crank conditions. Similarly, its 36-V input capability enables it to withstand transients commonly found in load-dump scenarios.
The device's 250-kHz to 2.5-MHz switching frequency is user programmable, enabling it to maximize efficiency while avoiding critical frequency bands such as AM radio bands in automotive applications. Its high frequency operation also enables the use of small, low-cost inductors and ceramic capacitors, resulting in low, predictable output ripple, Linear said.
The LT3507's low VCESAT (400 mV at 2 A and 350 mV at 1.5 A) internal switches offer efficiencies up to 88%, eliminating the need for external heat sinking. All three converters are synchronized to either a common external clock input or its internal oscillator.
The 2.4-A channel maintains a 180° phase offset between the two 1.5-A channels to reduce input ripple current. An internal 0.80-V reference enables sub 1-V 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 user programmable over-voltage and under-voltage lockouts. The low current (<1 uA) shutdown provides extended run-time in battery-powered systems.
Pricing: Starts at $4.25 each for the LT3507EUHF (5 x 7-mm QFN-38). The LT3507IUHF (industrial temperature I-grade: -40°C to 125°C), version and the LT3507HUHF (automotive H-grade: -40°C to 150°C) are priced at $5.10 and $5.35, respectively. All in quantities of 1,000.
Availability: From stock.
Product information: LT3507
Linear Technology, www.linear.com