Ramp controlled driver for series/parallel solid state lighting devices
View Patent ↗An electronic OLED driver apparatus is presented, which includes a DC-DC converter stage with a waveform generator generating converter setpoints with profiles having minimum rise time and fall time values.
1. An electronic driver apparatus for powering an OLED array, comprising:
a DC-DC converter with an input receiving DC input power and an output, the DC-DC converter comprising:
first and second switching devices coupled in series between first and second DC input terminals, the first and second switching devices being joined at an internal node,
a driver including a driver control input, the driver operative to provide first and second switch control signals in complementary fashion to the first and second switching devices, respectively, at least partially according to a signal received at the driver control input,
a filter circuit coupled between the internal node and the DC-DC converter output, and
a PWM circuit, comprising:
an error amplifier with a first input receiving a converter setpoint signal, a second input receiving a feedback signal representing current supplied to the driven OLED array, and an error amplifier output providing an error signal representing a difference between the converter setpoint signal and the feedback signal, and
a PWM controller with an input connected to the error amplifier output to receive the error signal, the PWM controller operative to provide a pulse width modulated signal to the driver control input according to the error signal; and
a waveform generator receiving an input setpoint signal, the waveform generator operative to provide the converter setpoint signal to the PWM circuit at least partially according to the input setpoint signal, the converter setpoint signal having rise time values of 1 us or more and 10 ms or less and fall time values of his or more and 10 ms or less.
2. The electronic driver apparatus of claim 1 , where the rise time values and the fall time values are different.
3. The electronic driver apparatus of claim 2 , where the waveform generator provides the converter setpoint signal having increasing and decreasing profiles, and where at least a portion of at least one of the increasing and decreasing profiles are linear.
4. The electronic driver apparatus of claim 2 , where the waveform generator provides the converter setpoint signal having increasing and decreasing profiles, and where at least a portion of at least one of the increasing and decreasing profiles are nonlinear.
5. The electronic driver apparatus of claim 2 , comprising a second DC-DC converter including an input coupled with the DC-DC converter output, and providing a second DC output to drive the OLED array.
6. The electronic driver apparatus of claim 1 , where the waveform generator provides the converter setpoint signal having increasing and decreasing profiles, and where at least a portion of at least one of the increasing and decreasing profiles are linear.
7. The electronic driver apparatus of claim 6 , where the waveform generator provides the converter setpoint signal having increasing and decreasing profiles, and where at least a portion of at least one of the increasing and decreasing profiles are nonlinear.
8. The electronic driver apparatus of claim 6 , comprising a second DC-DC converter including an input coupled with the DC-DC converter output, and providing a second DC output to drive the OLED array.
9. The electronic driver apparatus of claim 1 , where the waveform generator provides the converter setpoint signal having increasing and decreasing profiles, and where at least a portion of at least one of the increasing and decreasing profiles are nonlinear.
10. The electronic driver apparatus of claim 1 , comprising a second DC-DC converter including an input coupled with the DC-DC converter output, and providing a second DC output to drive the OLED array.
11. An electronic driver apparatus of claim 1 , comprising a plurality of DC-DC converters receiving the DC input power and providing individual outputs to drive corresponding OLED arrays, the DC-DC converters individually comprising:
first and second switching devices coupled in series between first and second DC input terminals, the first and second switching devices being joined at an internal node;
a driver including a driver control input, the driver operative to provide first and second switch control signals in complementary fashion to the first and second switching devices, respectively, at least partially according to a signal received at the driver control input;
a filter circuit coupled between the internal node and the DC-DC converter output;
a PWM circuit operative to provide a pulse width modulated signal to the driver control input according to a converter setpoint signal and a feedback signal; and
a waveform generator receiving an input setpoint signal, the waveform generator operative to provide the converter setpoint signal to the PWM circuit at least partially according to the input setpoint signal, the converter setpoint signal having rise time values of 1 μs or more and 10 ms or less and fall time values of 1 μs or more and 10 ms or less.
12. An electronic driver apparatus of claim 1 , comprising:
a plurality of DC-DC converters receiving the DC input power and providing individual outputs to drive corresponding OLED arrays, the DC-DC converters individually comprising:
first and second switching devices coupled in series between first and second DC input terminals, the first and second switching devices being joined at an internal node;
a driver including a driver control input, the driver operative to provide first and second switch control signals in complementary fashion to the first and second switching devices, respectively, at least partially according to a signal received at the driver control input,
a filter circuit coupled between the internal node and the DC-DC converter output, and
a PWM circuit operative to provide a pulse width modulated signal to the driver control input according to a converter setpoint signal and a feedback signal; and
a waveform generator receiving an input setpoint signal, the waveform generator operative to provide the converter setpoint signal to the plurality of DC-DC converters at least partially according to the input setpoint signal, the converter setpoint signal having rise time values of 1 μs or more and 10 ms or less and fall time values of 1 μs or more and 10 ms or less.
13. The electronic driver apparatus of claim 1 , where the input setpoint signal is a current control setpoint signal to set an output level of the DC-DC converter via the PWM circuit; and where the waveform generator is operative to provide the converter setpoint signal to the PWM circuit by slowing the rise and fall times of the current control setpoint signal to mitigate current spikes seen by an OLED array connected to the output of the DC-DC converter.
14. An electronic driver apparatus for powering an OLED array, comprising:
a DC-DC converter, comprising:
an input comprising first and second DC input terminals for receiving DC input power;
an output for providing DC output power to a driven OLED array;
first and second switching devices coupled in series between the first and second DC input terminals, the first and second switching devices being joined at an internal node,
a driver including a driver control input, the driver operative to provide first and second switch control signals in complementary fashion to the first and second switching devices, respectively, at least partially according to a pulse width modulated signal received at the driver control input,
a filter circuit coupled between the internal node and the output of the DC-DC converter, and
a PWM circuit, comprising:
an error amplifier with a first input receiving a converter setpoint signal, a second input receiving a feedback signal representing current supplied to driven OLED array, and an error amplifier output providing an error signal representing a difference between the converter setpoint signal and the feedback signal, and
a PWM controller with an input connected to the error amplifier output to receive the error signal, the PWM controller operative to provide a pulse width modulated signal to the driver control input according to the error signal;
a setpoint input for receiving an input setpoint signal to set an output level of the DC-DC converter via the PWM circuit; and
a waveform generator operative to provide the converter setpoint signal to the first input of the error amplifier of the PWM circuit at least partially according to the input setpoint signal, the converter setpoint signal having rise time values of 1 us or more and 10 ms or less and fall time values of 1 us or more and 10 ms or less.
15. The electronic driver apparatus of claim 14 , where the rise time values and the fall time values are different.