Date: 10/02/2009

Dual 2.2MHz, 36V, step-down DC/DC converter delivers 0.7A per channel

Linear Technology released the LT3509, a dual channel current mode PWM step-down DC/DC converter with two internal 36V, 1A power switches. Each channel is capable of delivering up to 700mA of output current with efficiencies up to 88%. Its wide input range of 3.6V to 36V, with transient protection to 60V makes it ideal for regulating power from a wide variety of sources, including unregulated wall transformers, 24V industrial supplies and automotive batteries.

For automotive applications, the LT3509's minimum input voltage of 3.6V enables it to operate with sub-4V inputs paramount for automotive "cold crank" requirements. Similarly, the device's 36V continuous input capability with 60V transient protection enables it to withstand transients found in load-dump scenarios. It's 300kHz to 2.2MHz switching frequency is user programmable, enabling it to maximize efficiency while using tiny, low cost inductors and ceramic capacitors, resulting in low, predictable output ripple.

The LT3509's low VCESAT (320mV @0.9A) internal switches offer efficiencies up to 88%, minimizing wasted heat. An internal 0.80V reference enables sub-1V output voltages required to power the latest generation of low voltage DSPs and microcontrollers. The internal cycle-by-cycle current limit provides protection against shorted outputs.

Other features include:

1. Over-Voltage Lockout Protects Circuit Through 60V Supply Transients
2. Short Circuit Robust
3. Low Dropout Voltage - 95% Maximum Duty Cycle
4. The low current (< 9µA) shutdown offers extended run-time in battery-powered systems.
5. Integrated Boost Diodes
6. Industrial temperature grades, LT3509IDE and LT3509IMSE, are tested and guaranteed to operate from a -40°C to 125°C operating junction temperature

Package:
1. LT3509EDE is available in a thermally enhanced 3mm x 4mm DFN-14
2. LT3509EMSE is available in a thermally enhanced MSOP-16E package.

Price:
1. Starts at $2.95 for LT3509EDE and $3.05 for LT3509EMSE each
2. LT3509IDE is priced at $3.39 and LT3509IMSE is priced at $3.51 each

Availability: All versions are available from stock.

For more information, visit www.linear.com