Torex Integrates Synchronous Step-Down DC/DC with NMOS LDO

12th March 2009

ES Admin

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Datasheet

The new XCM519 multi-chip module from Torex Semiconductor integrates an XC9235/XC9236 synchronous step-down DC/DC converter with a high performance XC6601 NMOS LDO (low dropout) voltage regulator in a cost-effective, space saving package. The module meets the requirements of battery-driven applications such as mobile phones, PDAs, gaming devices and Bluetooth equipment, with the DC/DC converter providing a step-down from the battery, and this lower voltage feeding the NMOS LDO to provide a highly stable, low noise supply for the equipment’s on-board processor’s core.

The DC/DC converter block operates from a supply voltage range between 2.7V and 6.0V, providing output voltages between 0.8V and 4.0V and output currents up to 600mA. The switching frequency can be selected from 1.2MHz or 3.0MHz as required. The XCM519 is available in two versions to provide PWM control or automatic PWM/PFM switching control, providing fast response, low ripple and high efficiency (92% typ) over the full load range.

The LDO regulator block operates from a BIAS voltage range of between 2.5V and 6.0V and an input voltage of between 1.0V and 3.0V, providing output voltages between 0.7V and 1.8V to an accuracy of ±20mV. Using an NMOS transistor driver instead of the more usual PMOS means the regulator has a much lower dropout voltage (just 35mV at 100mA), enabling the device to be used at lower input voltages. Load currents of up to 400mA can be achieved. Over-current protection and thermal shutdown circuits are included to protect the regulator against excess current draw or over-temperature.

Each block of the XCM519 includes a built-in UVLO (under-voltage lock out) function, and both blocks feature stand-by operating modes to greatly reduce power consumption. The XCM519 is available in a space saving, ultra small USP-12B01 (2.8 x 2.3 x 0.6mm) package, and requires the minimum number of components to build the complete power management circuit – all that is required is a small coil and ceramic capacitors connected externally.