2

FIGURE 2. SP6651A 1.5V OUTPUT EVALUATION BOARD SCHEMATIC

USING THE EVALUATION BOARD

1) Powering up the SP6651A Circuit & Programming the UVLO threshold

The SP6651A Evaluation Board can be powered from a single Li-Ion battery or a +2.7 to

+6.5V power supply. Connect with short leads directly to the “Vin” and “Gnd” posts.

Note the SP6651A will remain in “shutdown” until D0 or D1 of the Jumpers J1 or J2 are

applied to the Vin or position 1 to 2. See Table 1 for UVLO threshold programming and

D1 and D0 pin definition.

Table 1. Operating Mode Definition

D1

D0

Definition

0

0

Shutdown. All internal circuitry is disabled and the power switches are opened.

0

1

Device enabled, falling UVLO threshold = 2.70V

1

0

Device enabled, falling UVLO threshold = 2.85V

1

1

Device enabled, falling UVLO threshold = 3.00V

2) VOUT PROGRAMMING

The SP6651A requires 2 feedback resistors to control the output voltage. Connect the

appropriate resistors RF and RI (Table 2) from pin 6 SP6651A FB to Vout and to the

GND.

For Vout different from that shown in the Table 2, use equation:

RI

Vout

RF

•













−

=

1

8

.

0

3

Vout 1.5V 800mA

Vin 2.7 - 6.5VDC

3

1

RVIN

10.0

D0

RI

261K

SP6651A

U1

1

2

3

4

5

6

7

8

9

10

PVin

Vin

BLON

D1

D0

FB

Vout

GND

PGND

LX

J2

J1

COUT

22uF

CF

22pF

L1

10uH

CVIN

1.0uF

2

RF

226K

2

BLON

CIN

22uF

1

D1