ONET1130EC datasheet(29/60 Pages) TI1

29 / 60 page

ONET1130EC

www.ti.com

SLLSEJ3A – JUNE 2015 – REVISED JULY 2015

Feature Description (continued)

8.3.2.6 Loss of Signal Detection

The loss of signal (LOS) detection is done by 2 separate level detectors to cover a wide dynamic range. The

peak values of the input signal are monitored by a peak detector and compared to a pre-defined loss of signal

threshold voltage inside the loss of signal detection block. As a result of the comparison, the LOS signal, which

indicates that the input signal amplitude is below the defined threshold level, is generated. There are 2 LOS

ranges settable with the RXLOSRNG bit (bit 0 of register 4). With RXLOSRNG = 0 the high range of the LOS

assert values are used (40 mVPP to 130 mVPP) and by setting RXLOSRNG = 1 the low range of the LOS assert

values are used (10 mVPP to 50 mVPP). There are 64 possible internal LOS settings set with RXLOSA[0..5]

(register 7) for each LOS range to adjust the LOS assert level.

The typical LOS hysteresis, as defined by 20log(LOS de-assert voltage/LOS assert voltage) is 4 dB. This can be

reduced by approximately 2 dB by setting receiver hysteresis RXHYS = 1 (bit 7 of register 6). In addition, the

LOS detection time can be reduced by setting the receiver fast LOS bit RXFLOS = 1 (bit 3 of register 5);

however, this may result in chatter (LOS bounce).

8.3.3 Analog Block

8.3.3.1 Analog Reference and Temperature Sensor

The ONET1130EC is supplied by a single 2.5 V ±5% supply voltage connected to the VCC_TX, VCC_RX and

VDD pins. This voltage is referred to ground (GND) and can be monitored as a 10 bit unsigned digital word

through the 2-wire interface.

On-chip bandgap voltage circuitry generates a reference voltage, independent of the supply voltage, from which

all other internally required voltages and bias currents are derived.

In order to minimize the module component count, the ONET1130ECprovides an on-chip temperature sensor.

The temperature can be monitored as a 10 bit unsigned digital word through the 2-wire interface.

8.3.3.2 Power-On Reset

The ONET1130EC has power on reset circuitry which ensures that all registers are reset to default values during

startup. After the power-on to initialize time (tINIT1), the internal registers are ready to be loaded. The part is ready

to transmit data after the initialize to transmit time (tINIT2), assuming that the enable chip bit EN_CHIP = 1 (bit 0 of

The ONET1130EC bias current can be disabled by setting the TX_DIS pin high. The internal registers are not

reset. After the transmitter disable pin TX_DIS is set low the part returns to its prior output settings.

8.3.3.3 Analog to Digital Converter

The ONET1130EC has an internal 10 bit analog to digital converter (ADC) that converts the analog monitors for

temperature, power supply voltage, bias current and photodiode current into a 10 bit unsigned digital word. The

first 8 most significant bits (MSBs) are available in register 40 and the 2 least significant bits (LSBs) are available

in register 41. Depending on the accuracy required, 8 bits or 10 bits can be read. However, due to the

architecture of the 2-wire interface, in order to read the 2 registers, 2 separate read commands have to be sent.

The ADC is enabled by default so to monitor a particular parameter, select the parameter with ADCSEL[0..2]

(bits 0 to 2 of register 3). Table 2 shows the ADCSEL bits and the parameter that is monitored.

Table 2. ADC Selection Bits and the Monitored Parameter

ADCSEL2

ADCSEL1

ADCSEL0

MONITORED PARAMETER

Temperature

Supply voltage

Bias current

Photodiode current

Submit Documentation Feedback

Product Folder Links: ONET1130EC

ONET1130EC Datasheet(PDF) 29 Page - Texas Instruments

ONET1130EC Datasheet(HTML) 29 Page - Texas Instruments

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

Datasheet Download

Link URL