Some applications require a combination of low voltage in and a higher voltage at high current output. Examples include data-communications optical modules, dc motors, bias voltage for power amplifiers, laser diodes and some battery-powered equipment (see figure). The possible solutions are a dc-dc converter, a switching regulator, or Analog Devices’ new all-in-one LTM4661 µModule boost regulator.
The LTM4661 boost regulator µModule is used to power high-speed optical modules aimed at data centers and other data-communications applications.
The LTM4661 contains a dc-dc switching controller, power MOSFETs, inductors, and supporting components all inside a tiny 6.25- × 6.25- × 2.42-mm module in a BGA package. The input-voltage range is 1.8 to 5.5 V, while the output-voltage range is 2.5 to 15 V. Maximum output current is 4 A continuous with a 3.3-V in and 5-V out configuration. With 3.3-V in and 12-V out, the maximum current capability is 0.7 A. A plus feature of the LTM4661 is that it can operate with an input voltage down to 0.7 V after startup. The maximum total dc output voltage regulation over load, line, and temperature variations is ±3%.
The LTM4661 uses synchronous rectification to achieve an overall maximum efficiency of 92%, depending on load current. The basic internal switching frequency is 1 MHz, although switching can also be synched to an external clock in the 500-kHz to 1.5-MHz range. With most of the critical components inside the module, only one resistor to set the output voltage and three capacitors are needed externally, resulting in a diminutive PCB footprint. Other features include inrush current limit, output overvoltage and over-temperature protection, as well as an output disconnect in shutdown mode. The operating temperature range is −40 to 125°C.
The LTM4661 is in production now; pricing starts at $6.98 in 1K quantities. A demo board is available. Click here for a complete datasheet.
