Datasheet

PWM Dimming Using Enable Data
2-10
2.10 PWM Dimming Using Enable Data
For the PWM Dimming Using Enable method, the EVM is configured with
R2= open and R3 = short. Setting R4 = 61.9 Ω programs the maximum output
current to 20 mA. Figure 2−7 shows input current and output current with the
PWM frequency set to 100 Hz and 50% duty cycle. The top oscilloscope trace
is the output current and the bottom trace is the control voltage seen on the
EN pin. Note the three-stage soft start during the first 1.5 ms of each cycle.
Figure 2−8 shows the output current versus the duty cycle of the control
voltage.
Figure 2−7. Input Current and Output Current With PWM Dimming Using Enable
2 ms
10 mA/div
2 ms
62 mV
0.2 V
0.1 V
50 mV
2
3
4
1
BWL
DC x10
DC x10
DC
DC
2 DC 1.64 V
1 MS/s
AUTO
1
2 ms
2 V
2