“With up to 90dB PSRR [power supply ripple rejection], and output noise at 8μVrms, the AP7372 helps designers mitigate the effects of input source noise and meet output ripple and noise targets,” according to the company, which sees it being used in test, measurement, communication, industrial automation and medical equipment.
Output is up to 200mA, where drop-out is 120mV.
Five variants provide fixed output voltages of 1.2, 1.8, 2.5, 3.3 or 5V, and all of them can be adjusted upwards all the way to the input voltage – making the 1.2V version the most broadly adjustable variant.
Providing it is above the desired output voltage, plus the drop-out, the input voltage can be anywhere between 2.7V and a creditably high 20V – covering single-cell Li-ions and 12V rails, for example.
The 8μVrms output noise is for all variants, and PSSR is typically 90dB at 10kHz, 70dB at 100kHz and 52dB at 1MHz.
Packaging is 1.2x1mm six ball BGA, leaving two spare connections on top of ground, Vin, Vout and adjust.
These two balls are used to provide an enable connection and a connection for a soft-start capacitor.
Startup for the 5V version is typically in 340μs with the latter open, lengthening to ~14ms ramp with 10nF connected, for example.
The enable pin can be asserted all the way to Vin, and pulling it below ~1.1V disables the regulator, dropping quiescent current to a handful of μA. Maximum tail current when operating is around 600μA.
Protections include short-circuit, over-current and over-temperature – operating junction temperature is -40°C to +125°C, and junction-to-board thermal resistance, important on such a tiny linear regulator, is 28.29°C/W.
Input and output capacitors of at least 1.5μF over tolerance, voltage and temperature are needed (2.2μF ceramic capacitors are suggested). Caveats for the output capacitor are a maximum of 22µF and an ESR (effective series resistance) between 1mΩ and 300mΩ. “X7R and X5R type capacitors are recommended, whereas Y5V and Z5U capacitors are not recommended for use with any LDO,” said Diodes.
Find the AP7372 data sheet here
Nisshinbo Micro Devices launched an LDO for audio with a similar spec last year, although it tolerates only up to 5.5Vin.
