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dc1573af
DEMO MANUAL DC1573A
terMinAl options
FAULT
: The
FAULT
terminal is tied directly to the
FAULT
pin. If there is a fault condition, the
FAULT
terminal is
pulled low. When there is no fault, the terminal is pulled
up to V
IN
. This terminal can be monitored with a voltage
meter, tied to the input of another device, or left floating.
SHDN
/UVLO: This terminal is tied directly to the
SHDN
/
UVLO pin. A resistor divider from PV
IN
to GND sets the
voltage on this terminal/pin. These resistors can be easily
adjusted for both the UVLO level and the amount of rising
hysteresis. See the data sheet for details. The terminal can
also be used to shut the IC down and turn off the LEDs.
Tie the terminal directly to GND in order to place the IC
in shutdown and turn off the LEDs.
CTRL: This terminal is tied directly to the CTRL pin. As
assembled, there is a 1M resistor pulling the CTRL pin up
to REF. The CTRL pin voltage can be adjusted for analog
dimming as shown in the data sheet. Either a voltage on
the CTRL terminal can be driven to dim the LEDs or a
resistor divider (R2 and R5) from PV
IN
to GND can be
added to reduce the CTRL voltage as PV
IN
drops too low.
Pulling the CTRL pin to GND turns the LEDs off.
PWM: This terminal is tied directly to the PWM pin. As
shown in the data sheet, an input PWM waveform turns the
LEDs ON and OFF. Dimming frequency and dimming range
are discussed in the data sheet. When PWM dimming is
not being used, tie PWM to REF with a 0Ω resistor (R9)
or place a 3.3V or 5V DC source on the PWM terminal.
SYNC: This terminal is tied directly to the SYNC pin. As
assembled, SYNC is disabled and tied directly to GND
with a 0Ω resistor (R6). For SYNC to be used, R6 must
be removed and a SYNC signal must be applied to this
terminal.
INTV
CC
: This terminal is tied directly to the INTV
CC
pin.
This terminal is provided to be able to monitor the voltage
on the INTV
CC
regulator or to provide an external INTV
CC
source to the IC. In some low voltage applications, INTV
CC
can be tied directly to PV
IN
or V
IN
. See the data sheet for
details. For normal operation, leave this terminal floating.
LED+ and LED1-8: The eight LED+ terminals are the output
voltage of the boost regulator and they are all tied together
on the PCB. The anodes of the LED strings should be tied
to these terminals and the cathodes to LED1-8 terminals.
If an LED1-8 terminal is not used, it should be tied directly
to LED+. If all LED+ to LED1-8 connections are left float-
ing or are opened during operation, DC1573A powers the
output to 55V as programmed by OVPSET. It is okay to
connect LEDs to the LED+ and LED1-8 terminals when it
is powered to OVP. See data sheet for details.
LED1-8 terminals can be tied together to get more than
100mA per LED string. Pairs of LED1-8 terminals can be
tied together for 4× 200mA LED strings as an example.
Individually, each LED1-8 pin can source a maximum of
100mA, but they can be tied together for more.