Nouvelles

2A 32V dc-dc converter includes mosfets in 2.8x3mm

Efficiency can be 88% at 5mA out, with quiescent as low as 22µA.

The devices are:

AP63200: 500kHz, PWM/PFM, variable out, can operate as LDO (100% duty)
AP63201: 500kHz, PWM only, variable out, can operate as LDO (100% duty)
AP63203: 1.1MHz, PWM/PFM, fixed 3.3Vout
AP63205: 1.1MHz, PWM/PFM, fixed 5.0Vout
To reduce light-load waste, PFM is available on some of the models – efficiency can be as 88% with a 5mA load (and 80% at 1mA). The AP63201 remains in PWM at all times.




Output mosfets (125mΩ high-side, 68mΩ low-side power) are built-in, and the drive waveform is optimised to reduce output EMI – see diagram – “which reduces switching node ringing without sacrificing MOSFET turn-on and turn-off times,” said the firm.
For further EMI reduction, the switching signal is jittered ±6% to spread the output spectrum.

Diodes-AP63200-01-03-05-block

The enable pin can be operated by a digital signal (device current ~1μA), and also has a reference built-in (threshold 1.18Vtyp rising, 1.1V falling) so that it can be used for under-voltage lock-out.

Built-in under-voltage lock-out (enable tied to Vin) is triggered if the input falls below 3.1V.

For higher lock-out voltage, current sources inside the chip deliver 1.5μA to the enable pin all times (if there is a load to ground on it), and an extra 4μA once the device is enabled. These two current levels allow an external potentiometer to set a lock-out voltage with hysteresis.

Built-in soft-start delay is 4ms.

Pin-out is such that a single-sided pcb is possible, although heavy (2oz) copper on both sides is suggested in view of the dissipation associated with delivering up to 2A.

All devices have been designed to withstand 40V for 400ms on the input, and come in a TSOT26 package.

Applications are foreseen in home appliances, industrial electronics, telecomms, power tools, office equipment, TVs and set-top boxes.