MAX1573 Datasheet, PDF (2/4 Pages) Maxim Integrated Products – MAX1573 Evaluation Kit

MAX1573 Evaluation Kit
Table 1. JU1 and JU2 Functions (Dimming Control)
JU1 POSITION
1 and 2
1 and 2
2 and 3
2 and 3
EN1
Connected to VIN
Connected to VIN
Connected to GND
Connected to GND
JU2 POSITION
1 and 2
2 and 3
1 and 2
2 and 3
EN2
Connected to VIN
Connected to GND
Connected to VIN
Connected to GND
MAX1573 OUTPUT
Full brightness
3/10 brightness
1/10 brightness
Shutdown
6) Sweep the power supply to 5.5V. Verify that all 4
LEDs remain on with constant and uniform intensity.
7) Reconfigure JU1 and JU2 to verify the different
brightness levels. For instructions on brightness
control, see Table 1.
Detailed Description
Jumper Selection
EN1 and EN2 on the MAX1573 provide control for
ON/OFF, 1/10, 3/10, and full current. JU1 and JU2 con-
nect these 2 pins to either VIN or GND (see Table 1).
An external signal can be used to drive EN1 or EN2 by
removing the corresponding shunt completely from the
jumper and connecting the external signal to the
appropriate connecting pad.
Setting LED Current
The default LED current is set to 17mA (with shunts
across pins 1 and 2 on JU1 and JU2). To set a different
LED current, change R1, where R1 = 215 x 0.6 /
I_LED(FULL).
Evaluating Off-Board LEDs
The MAX1573 EV kit allows for easy evaluation of off-
board LEDs. To evaluate off-board LEDs, first cut the
trace that shorts JU3. Next, connect the pad labeled
VOUT on the EV kit to the anodes of the LEDs under
evaluation. Last, connect the cathode of each LED to
one of the EV kit pads labeled LED1–LED4. If evaluat-
ing fewer than 4 off-board LEDs, see the Evaluating
Fewer Than 4 LEDs section.
Evaluating Fewer than 4 LEDs
To evaluate fewer than 4 LEDs, remove the desired
LED(s) and connect the corresponding LED pad(s) to
the input voltage. Do not leave LED pad(s) floating.
VIN
2.7V TO 5.5V
EN1/PWM
C1
1µF
1 _JU1
2
3
EN2
1 _JU2
2
3
GND
R1
7.5kΩ
1%
C2
C3
1µF
1µF
VOUT
D1
C1N
C1
IN
A3 _EN1
A4 _EN2
B4 _SET
A1 B1
C1P C2N
U1
MAX1573
GND
D2
B2
C2P
A2
OUT
C4
1µF
LED1 ^D4
LED2 ^C4
LED3 ^D3
LED4 ^C3
JU3
SHORT
D1 D2 D3 D4
LED1
LED2
LED3
LED4
GND0
Figure 1. MAX1573 EV Kit Schematic
2 _______________________________________________________________________________________