Unless otherwise noted Vin = 12.00 Volts DC , Ta = 25 oC and unit has been running for 20 minutes.
- 160 -
Control Full On
Vctrll - <.5 -
Control Full Off
Vctrlh - >4.5 -
Control Input Bias Current
- 10 uA
Vin Input voltage to the inverter. Both pins should be connected for optimum reliability and efficiency .
Inverter ground. Both pins should be connected for optimum reliability and efficiency.
Analog voltage input to the onboard pulse width modulator. Increasing this voltage increases the off
time of the onboard PWM resulting in decreased brightness.
Inverter Enable/Disable. If this pin is driven high, the inverter is enabled. Pull this pin low to disable
The 8mF4 series of inverters is designed to power up to four cold cathode fluorescent lamps with combined
power from ten watts to forty watts. An external enable/disable control and an onboard analog controlled pulse
width modulator provide flexibility in allowing either PWM or analog methods for dimming. The 8mF4 inverter can
reliably dim to less than 0.5% duty cycle, which results in an electrical dimming ratio of greater than 200:1.
Depending upon the attached backlight assembly, optical dimming ratios of greater than 1000:1 can be
accomplished. Graph 1 shows the relationship of relative brightness to duty cycle for a typical backlight assembly.
External shutdown or external PWM operation of the inverter is accomplished using the Enable/Disable pin.
Enabling the inverter is accomplished by pulling this pin high (above Vthon). Pulling this pin low (below Vthoff)
disables the inverter.
If analog voltage dimming is required, the onboard PWM can be enabled. The analog voltage is applied to the
Control pin. Figure 1 shows how to connect the inverter for onboard PWM operation. Graph 2 shows the
relationship of PWM duty cycle to input control voltage.
If an external PWM is used, connect the enable pin to the PWM source and connect the control pin to the inverter
ground. If the onboard PWM is used, connect the analog voltage to the control pin.