MAX1649 Evaluation Kit

2

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_______________Detailed Description

Shutdown Control

The MAX1649 provides a SHDN pin to disable the out-

put. Table 1 lists the options available for shutdown

control jumper JU1. An external controller can be used

by removing the shunt on JU1 completely and connect-

ing the external controller to the pad labeled SHDN.

SHDN is a TTL/CMOS logic-level input.

Output Voltage Adjustment

The output voltage can be adjusted with minor modifi-

cations to the EV kit board. First, select output voltage-

divider resistors R2 and R3 (refer to the Setting the

Output Voltage section of the MAX1649 data sheet).

Second, open jumper JU3 and resistor R3 by cutting

the thin PCB trace between their pads. Finally, install

R2 and R3. The standard output filter capacitor is rated

at 10V. Use a higher-rated capacitor if necessary.

When using the MAX1651 or when adjusting the output

of either device, an input voltage below 5.5V is accept-

able. However, the input voltage must be high enough

to avoid dropout (refer to the Typical Operating Charac-

teristics of the MAX1649/MAX1651 data sheet).

Evaluating the MAX649/MAX651/MAX652

The MAX1649 EV kit can also be used to evaluate the

MAX649/MAX651/MAX652. In addition to replacing the

MAX1649 with a MAX649, change resistor R1 to 0.1

Ω.

Contact Maxim for free samples of the MAX649CSA,

MAX651CSA, or MAX652CSA. Note that the MAX1649/

MAX1651 are recommended over the MAX649/

MAX651/MAX652 for new designs.

Table 1. Jumper JU1 Functions

MAX1649

V+

SHDN

REF

GND

FB

OUT

EXT

CS

5

3

3

1

4

8

6

7

1

2

3

4

5

6

7

8

1

2

VIN

SHDN

5.5V TO 16.5V

C1

68

μF

20V

C4

0.1

μF

C6

68

μF

20V

R1

0.05

Ω

1%

U1

JU1

OFF

ON

2

R3

SHORT

(PCB TRACE)

R2

OPEN

C5

OPEN

JU3

P1

L1

47

μH

D1

VOUT

C2

330

μF

10V

C7

OPEN

GND

C3

0.1

μF

Figure 1. MAX1649 EV Kit Schematic

SHUNT LOCATION

SHDN PIN

MAX1649 OUTPUT

1 and 2

Connected to GND

MAX1649 enabled,

2 and 3

Connected to VIN

Shutdown mode,