June 21-07 revH

SP7680: Complete Backlight Solution



2007 Sipex Corporation

Page 11

*When WZ=0 and WP=0 all registers are set to zero.

Bits B5, B4, B3, B2 and B1 are for read back only.

Bit B5 is held high whenever any kind of fault

condition exists on the SP7680. Bits B4, B3 and B2

indicate the specific fault condition, over-voltage

(B4=1), over-temp (B3=1) or undervoltage lockout

(B2=1). B1 communicates the state of the charge

pump, (B1=1 for 1.5x mode or B1=0 for 1x mode).

B0 of the STATUS register is used to select between

automatic charge pump mode selection and forced

charge pump mode selection. If B0 is low then the

charge pump mode (1X or 1.5X) is automatically

selected.

If B0 is high then the charge pump is

forced into either 1X mode or 1.5X mode depending

upon B0 of the CNTRL register.

Fault Conditions

For all three fault conditions:

Under Voltage Lockout

Over Temperature Detection

Over Voltage Protection

Upon entering any of these fault modes, the LED

drivers should turn off but the register contents

should remain unchanged with the exception of the

fault mode readback bits of the status register. The

WZ and WP bits of the status register should also

remain unchanged. The microprocessor should not

have to reset the SP7680 if it goes into fault mode.

The chip should continuously monitor its fault

indicators and when the fault condition is no longer

present, normal operation can resume.

CNTRL Register

In the CNTRL register B1, B2, B3 and B4 are used

to control the four MAIN LEDs, bits B5 and B6 are

used for the two SUB LEDs, and B7 is used for the

AUX LED.

To enable an individual LED the

corresponding bit is active high.

When B0 of the STATUS register is high, B0 of the

CNTRL register is used to force the charge pump

into 1X mode (CNTRL B0=low) or 1.5X mode

(CNTRL B0=high).

When B0 of the STATUS

register is low then CNTRL B0 is ignored.

WZ

WP

State

Iq

LED

drivers

0

0

Shutdown

and

reset

registers

to

00000000

0uA

Off

0

1

Shutdown - keep

register contents

0uA

Off

1

0

Standby

-

keep

register contents –

bandgap and other

analog

circuits

active, Vin shorted

to

Vout

through

internal switch

200uA

Off

1

1

Active

Active

Iq

On

APPLICATIONS INFORMATION