1.244V

ENM

Bit 0

ENS

Bit 1

UNI

Bit 2

RMP0

Bit 3

RMP1

Bit 4

OLED

Bit 5

1

Bit 7

1

Bit 6

MSB

LSB

General Purpose Register

Register Address 0x10

LM3528

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SNVS513B – AUGUST 2008 – REVISED MAY 2013

Figure 41. General Purpose Register Description

Table 2. General Purpose Register Bit Function

Bit

Name

Function

Power-On-

Value

0

ENM

Enable MAIN. Writing a 1 to this bit enables the main current sink (MAIN). Writing a 0 to this bit

0

disables the main current sink and forces MAIN high impedance.

1

ENS

Enable SUB/FB. Writing a 1 to this bit enables the secondary current sink (SUB/FB). Writing a 0 to

0

this bit disables the secondary current sink and forces SUB/FB high impedance.

2

UNI

Unison Mode Select. Writing a 1 to this bit disables the BSUB register and causes the contents of

0

BMAIN to set the current in both the MAIN and SUB/FB current sinks. Writing a 0 to this bit allows the

current into MAIN and SUB/FB to be independently controlled via the BMAIN and BSUB registers

respectively.

3

RMP0

Brightness Rate of Change. Bits RMP0 and RMP1 set the rate of change of the LED current into

0

MAIN and SUB/FB in response to changes in the contents of registers BMAIN and BSUB (see

4

RMP1

0

Brightness Rate of Change Description).

5

OLED

OLED = 0 places the LM3528 in White LED mode. In this mode both the MAIN and SUB/FB current

0

6

Don't Care

These are non-functional read only bits. They will always read back as a 1.

1

7

Table 3. Operational Truth Table

UNI

OLED

ENM

ENS

Result

X

0

0

0

LM3528 Disabled

1

0

1

X

MAIN and SUB/FB current sinks enabled. Current levels set by contents

of BMAIN.

1

0

0

X

MAIN and SUB/FB Disabled

0

0

0

1

SUB/FB current sink enabled. Current level set by BSUB.

0

0

1

0

MAIN current sink enabled. Current level set by BMAIN.

0

0

1

1

MAIN and SUB/FB current sinks enabled. Current levels set by contents

of BMAIN and BSUB respectively.

X

1

1

X

SUB/FB current sink disabled (SUB/FB configured as a feedback pin).

MAIN current sink enabled current level set by BMAIN.

X

1

0

X

SUB/FB current sink disabled (SUB/FB configured as a feedback pin).

MAIN current sink disabled.

* ENM ,ENS, or OLED high enables analog circuitry.

Brightness Registers (BMAIN and BSUB)

With the UNI bit (General Purpose register) set to 0 (Non-Unison mode) both brightness registers (BMAIN and

but with only the 7 LSB’s controlling the current. The MSB’s is a don’t care. The LED current control is designed

to approximate an exponentially increasing response of the LED current vs increasing code in either BMAIN or

(2)

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