DS1884 datasheet(24/92 Pages) MAXIM

24 / 92 page

DS1884

SFP and PON ONU Controller

with Digital LDD Interface

Maxim Integrated

Figure 7. Low-Voltage Hysteresis Example

Delta-Sigma Output and Reference

One delta-sigma output (DAC) is provided. This provides

a 9-bit resolution output. The maximum voltage output is

set by the input REFIN. An inexpensive shunt reference is

recommended to generate the voltage applied to REFIN,

as shown in Figure 8. The output includes the ability to

compensate the APD bias for temperature as given by

the following formula:

DAC_INT = TINDEX[6:0] + DAC OFFSET

If INV_DAC = 0, then DAC[9:0] = DAC_INT/DACFS x

VREFIN.

If INV_DAC = 1, then DAC[9:0] = [3FF - (DAC_INT/

DACFS)] x VREFIN.

where:

1) INV_DAC is at A2h Table 02h, Register 8Dh, bit 7.

2) TINDEX is at A2h Table 02h, Register 81h.

3) DAC OFFSET is an 8-bit value, representing the 8

MSBs of a 10-bit value. The two LSBs are 0.

4) DACFS (A2h Table 02h, Register 88h) is an 8-bit

value, representing the 8 MSBs of a 10-bit value. The

two LSBs are 0.

5) DAC is a 10-bit value.

6) The DAC[9:0] is clamped at DACFS.

7) DAC_INT is an internal signal.

Figure 8. Recommended Shunt Reference and RC Filter for

DAC Output

VPOA

VPOD

VCC

SEE

RECALLED VALUE

PRECHARGED

TO 0

PRECHARGED

TO 0

PRECHARGED TO 0

SEE RECALL

DS1884

REFIN

2.5V

0.1µF

0201

ZTL431A

SOT23

1µF

0402

CONNECT TO

CONTROL INPUT

ON DC-DC

39.2kΩ

0201

DAC

68.1kΩ

0201

1kΩ

0201

20kΩ

0201

VCC

DS1884 Datasheet(PDF) 24 Page - Maxim Integrated Products

DS1884 Datasheet(HTML) 24 Page - Maxim Integrated Products

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92

Datasheet Download

Link URL