Datasheet

MAX16814 Evaluation Kit
Evaluates: MAX16814
_______________________________________________________________________________________ 5
Additional Configurations and Features
The EV kit includes several other features to facilitate
evaluation of the IC. HB LED digital dimming control,
fault management through a FLT signal, synchronizing to
an external clock using the RT signal, and reconfiguring
the OVP for other voltages are detailed in the following
sections.
HB LED Digital-Dimming Control
The EV kit features a DIM PCB input pad for connect-
ing an external digital PWM signal. The DIM PCB pad
is pulled up to VCC by resistor R8. Apply a digital PWM
signal with a 0.8V logic-low (or less) and a 2.1V logic-
high (or greater) level, and frequencies from 100Hz to
20kHz. To adjust the HB LED brightness, vary the signal
duty cycle from 0 to 100% and maintain a minimum pulse
width of 1Fs. Apply the digital PWM signal to the DIM
and SGND PCB pads. Refer to the LED Dimming Control
section in the MAX16814 IC data sheet for additional
information on the MAX16814 dimming feature.
FLT and RT (External Clock
Synchronizing) Signals
The EV kit features the IC’s FLT and AC-coupled RT
signals. The FLT signal is pulled up to VCC by resistor
R9. The FLT signal is pulled low when there are open
or shorted HB LED(s) on an OUT_ channel or a thermal
shutdown condition has occurred. Refer to the Fault
Protections section in the MAX16814 IC data sheet for
further information on the FLT signal.
The SYNC PCB pad is used for connecting an
external clock for synchronizing the IC switching fre-
quency through its RT pin. The signal must also have
a 4V
P-P
amplitude and frequencies from 390kHz to
410kHz. Apply the external clock signal to the SYNC
and SGND PCB pads. Refer to the Oscillator Frequency/
External Synchronization section in the MAX16814 IC
data sheet for additional information on the MAX16814
synchronizing feature.
OVP Configuration
The IC OVP resistors (R6 and R7) are configured for an
OVP of 33V. This sets the maximum channel (VOUT)
voltage at 33V. Capacitor C9 provides noise filtering to
the OVP signal. To reconfigure the circuit for a different
OVP voltage, replace resistor R6 with a different value
using the following equation:
OVP
R6 1 x R7
1001.235
 
= −
 
 
where R7 is 10kI, OVP is the overvoltage protection
voltage desired, and R6 is the new resistor value for
obtaining the desired overvoltage protection. Refer to
the Open-LED Management and Overvoltage Protection
section in the MAX16814 IC data sheet for additional
information on the OVP feature.