MAX1573 Evaluation Kit

2

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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 /

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.

MAX1573

VOUT

OUT

LED1

D4

LED1

LED2

LED3

LED4

A2

IN

C2

1

µF

C3

1

µF

EN1

EN2

SET

C1

JU1

JU2

C4

D3

C3

D2

B2

B1

A1

D1

C1N

C1P

C2N

C2P

D4

U1

LED2

LED3

LED4

GND

D3

D2

D1

JU3

SHORT

C4

1

µF

C1

1

µF

R1

7.5k

Ω

1%

VIN

2.7V TO 5.5V

EN1/PWM

EN2

GND

1

2

3

1

2

3

A3

A4

B4

GND0

JU1 POSITION

EN1

JU2 POSITION

EN2

MAX1573 OUTPUT

1 and 2

Connected to VIN

1 and 2

Connected to VIN

Full brightness

1 and 2

Connected to VIN

2 and 3

Connected to GND

3/10 brightness

2 and 3

Connected to GND

1 and 2

Connected to VIN

1/10 brightness

2 and 3

Connected to GND

2 and 3

Connected to GND

Shutdown

Figure 1. MAX1573 EV Kit Schematic

Table 1. JU1 and JU2 Functions (Dimming Control)