AD8158 查看數據表（PDF） - Analog Devices

零件编号

产品描述 (功能)

比赛名单

AD8158

6.5 Gbps Quad Buffer Mux/Demux

Analog Devices 

APPLICATIONS INFORMATION

SUPPLY SEQUENCING

Ideally, all power supplies should be brought up to the appropri-

ate levels simultaneously (power supply requirements are set by

the supply limits in Table 1 and the absolute maximum ratings

listed in Table 3). In the event that the power supplies to the

AD8158 are brought up separately, the supply power-up sequence

is as follows: DVCC powered first, followed by VCC, and lastly

VTTI and VTTO. The power-down sequence is reversed with VTTI

and VTTO being powered off first.

VTTI and VTTO contain ESD protection diodes to the VCC power

domain (see Figure 38 and Figure 39). To avoid a sustained high

current condition in these devices (ISUSTAINED < 100 mA), the

VTTI and VTTO supplies should be powered on after VCC and

should be powered off before VCC.

If the system power supplies have a high impedance in the

powered off state, then supply sequencing is not required

provided the following limits are observed:

• Peak current from VTTI or VTTO to VCC < 200 mA

• Sustained current from VTTI or VTTO to VCC < 100 mA

SINGLE SUPPLY vs. MULTIPLE SUPPLY

OPERATION

The AD8158 supports a flexible supply voltage of 1.8 V to 3.3 V.

For some dc-coupled links, 1.2 V or ground-referenced signaling

may be desired. In these cases, the AD8158 can be run with a

split supply configuration.

AD8158

Table 22. Alternate Supply Configuration Examples

Signal Level

VCC, VTTI, VTTO

VEE

1.2 V CML

1.2 V

−2.1 V ≤VEE ≤ −0.6 V

GND − 400 mV diff GND

−3.3 V ≤VEE ≤ +1.8 V

The AD8158 control signals are always referenced between

DVCC and VEE and, when using a split supply configuration,

logic level-shift circuits should be used. The evaluation board

design shows the use of the Analog Devices, Inc., ADUM1250

I2C isolator and a level shifter to level-shift the SCL and SDA

signals.

Evaluation of DC-Coupled Links

When evaluating the AD8158 dc-coupled, remember that most

lab equipment is ground referenced while the AD8158 high

speed I/O are connected by 50 Ω on-die termination resistors to

VTTI and VTTO. To interface the AD8158 to ground-referenced,

high speed instrumentation (for example, the 50 Ω inputs of a

high speed oscilloscope), it is necessary to level-shift the outputs by

either using a dc-blocking network or by powering the AD8158

between ground and a negative supply.

For example, to evaluate 1.8 V dc-coupled transmitter perfor-

mance with a 50 Ω ground-referenced oscilloscope, use the

following supply configuration:

VCC = VTTO = VTTI = Ground

VEE = −1.8 V

Ground < DVCC < 1.5 V

Rev. 0 | Page 31 of 36

Share Link: