Comparing the two LED flash controllers from NXP, the SSL3250A is an asynchronous boost converter while the SSL3252 is a synchronous boost converter. The SSL3252 has the diode integrated in the device while the SSL3250A doesn’t and requires an external diode to be mounted on the PCB. The SSL3252 has built-in circuitry to detect a broken coil and hence fail safe, while the SSL3250A does not have the broken coil detection feature. The SSL3250A comes in a 16-terminal HVQFN package while the SSL3252 comes in a smaller 12-terminal chip scale package that is more suitable for handheld systems where space is a premium.