To provide a light emitting element driving circuit and a portable device capable of outputting stable driving voltage, even when driving of the light emitting element is switched from that with battery voltage to that with boosting voltage.
The light emitting element driving circuit for driving at least one or more of light emitting elements comprises a power supply circuit for generating driving voltage supplied to one end of the light emitting element, and a constant current circuit connected to the other end of the light emitting element for driving the light emitting element at a constant current. The power supply circuit includes a first reference voltage generating circuit for generating a first reference voltage on the basis of the driving voltage. The other end voltage of the light emitting element or voltage based on the other end voltage is assumed to be a second reference voltage, and the foregoing driving voltage is generated in accordance with a comparison result of the second reference voltage and the first reference voltage.
COPYRIGHT: (C)2007,JPO&INPIT
ANDO TSUTOMU
TSUCHIYAMA TOMONORI
| JP2005229733A | 2005-08-25 | |||
| JP2007201470A | 2007-08-09 | |||
| JP2005026431A | 2005-01-27 |
| WO2004100614A1 | 2004-11-18 |