LDS8161/41

© 2009 IXYS Corp.

6

Doc. No. 8141/61_DS, Rev. N1.0

Characteristics subject to change without notice

LDS8161 / 41 REGISTERS DEFINITION AND PROGRAMMING

Note: Unlisted register addresses are for factory use only; For proper operation write only to registers defined.

ADDRESS

DESCRIPTION

BITS

NOTES

00h

Bank A Current setting

8

01h

Bank B Current setting

8

02h

Bank C Current setting

(8161 only; Not for 8141)

8

converted into hex format

03h

Channel Enable

(No Bits 5, 4 for C2 and

C1 respectively for 8141)

6

Bits 5:0 = 1 enables LEDs C2, C1, B2, B1, A2, A1

respectively (See

Table 1). Both LEDs from one bank should be disabled to

minimize power consumption.

05h

Bank A, B, C PWM Duty

Cycle

8

Log Mode:

~ – 0.17dB dimming per LSB for currents > 300 µA; Refer to

8 to 12 bit conversion curve (Figure 3 and Table 10) for

resolution in range 0 – 300 µA

Data Code 00h = 0% Duty Cycle, FFh = 100% Duty Cycle

Example: 50% brightness reduction ( – 6dB) requires: 255 –

(– 6 dB / – 0.17 dB) = 255 – 35 = 220 (decimal) = DCh steps

19h

LED Diagnostics Test

8

See Table 2; Bit 5 = 1 sets user-initiated LED short/open

diagnostic

1Ch

LED Faults Status

( shorted to GND)

5

Bits from bit 5 to bit 0 represent LED status for LEDC2 –

LEDA1 respectively. Bit = 1 represents LED shorted to GND

1Dh

LED Faults Status

5

Bits from bit 5 to bit 0 represent LED status for LEDC2 –

LEDA1 respectively. Bit = 1 represents LED shorted to

1Eh

Configuration register

8

See Table 3

1Fh

Software reset, Standby

8

See Table 4

49h

Ta-Tj Temperature Offset

8

Since junction temperature is measured, the values loaded

here allow an offset to account for Tj – Ta gradient.

This allows de-rate tables to be referenced to Ta levels.

Two 4 bit offsets value for the LED and the Si Diode;

Bit [7:4] = Tj-Ta offset for the LEDs

Bit [3:0] = Tj-Ta offset for the Si diode.

Typically should set both offsets to be equal.

See Table 5 & 6

4Ah

LED Shutdown

Temperature

5

Defines T-code, at which LED current shuts down per LED

vendor de-rating specification (see Table 5); Factory default

value = 11100 (bin) = 1Ch represents 105

4Bh

2-x Table enable and

breakpoint (T-code)

6

Bit 5 = 1 – enable 2-x scale

LUT ΔPWM code correction (de-

rating) starting at the breakpoint set by T-code (bits 4:0)

Bit 5 = 0 – 1-x scale (default) for entire temperature range

Bit [4:0] defines T-code, where temperature de-rating starts,

or where 2-x scaling begins (see Table 5)

56h – 5Dh

Temp De-rating LUT

25C to 100C

(one 5C step every

nibble)

ΔPWM code1[7:4],

ΔPWM code0[3:0] –

ΔPWM code13[7:4],

ΔPWM code12[3:0]

8

Two LUT words per I

Each word contains two 4-bit numbers repr

esenting of ΔPWM

codes. See

Table 6 and Appendix 1 for LUT programming.

Factory default setting is Logarithmic Mode table for WLED

LED (Nichia NSSW020BT WLED).

Default table could be used for WLED de-rating.

De-Rating starts at 55ºC junction.