US 12,452,974 B2
Light emitting element driving device
Toru Takahashi, Kyoto (JP); Kei Nagao, Kyoto (JP); and Masaaki Nakayama, Kyoto (JP)
Assigned to Rohm Co., Ltd., Kyoto (JP)
Filed by ROHM CO., LTD., Kyoto (JP)
Filed on Sep. 13, 2023, as Appl. No. 18/466,319.
Application 18/466,319 is a continuation of application No. PCT/JP2022/009092, filed on Mar. 3, 2022.
Claims priority of application No. 2021-042523 (JP), filed on Mar. 16, 2021.
Prior Publication US 2023/0422372 A1, Dec. 28, 2023
Int. Cl. H05B 45/30 (2020.01); H05B 45/10 (2020.01); H05B 45/325 (2020.01); H05B 47/14 (2020.01); H05B 47/17 (2020.01)
CPC H05B 45/325 (2020.01) [H05B 45/10 (2020.01); H05B 47/14 (2020.01); H05B 47/17 (2020.01)] 13 Claims
OG exemplary drawing
 
1. A light emitting element driving device comprising:
a current driver configured to generate a current to be passed in light emitting elements for a plurality of channels;
a dimming controller configured to control the current driver;
a control logic circuit including a register; and
an external terminal to which a setting resistor is configured to be externally connected,
wherein
in a normal mode in which light emission control for the light emitting elements is performed by the dimming controller, if no communication signal from an external microprocessor is recognized beyond a first predetermined period, the control logic circuit shifts from the normal mode to a first limp home mode, and
in the first limp home mode, the dimming controller
sets a light emitting element current set value based on a terminal current set value commensurate with a resistance value of the setting resistor as well as a DC dimming set value for each of the channels set in the register,
controls the current driver so as to generate a current with the set light emitting element current set value, and
turns on and off the current driver based on a PWM on-duty set value for each of the channels set in the register.