Sundance SMT916 - Manual (Page 22)

4 Verification Procedures
Connections between base and mezzanine module will be verified by either probing
on the board itself or by a mean of sending and checking known data from a host
server.
ADC performance will be verified channel by channel as well as crosstalk between
channels.
5 Power Consumption – Heat dissipation.
5.1 AD7626 ADC Chip.
Three power supplies are required for the AD7626:
- VDD1 (5 Volts), with a maximum current of 11.2mA (56mW),
- VDD2 (2.5 Volts), with a maximum current of 27.8mA (69.5mW),
- IO (2.5 Volts), with a maximum current of 17.8mA (44.5mW).
The total power consumed/dissipated by one ADC (5mm x 5mm package) is
equivalent to 170mW. With a thermal resistance (Junction to ambient) of 40˚C/W,
the elevation in temperature will be 6.8˚C.
These figures are acceptable and no heatsink should be required for the module to
be used in a open environment.
5.2 Linear regulators.
All 3 rails mentioned in the previous section (ADC) will be coming out of linear
regulator with high-PSRR where switching frequencies of DC/DC using on base
modules are. TPS793xx family from Texas Instrument will be used on the SMT916.
Regulators come is small packages (5-pin BGA – YZQ). This specific package shows a
thermal resistance of 255˚C/W (worst case).
A 5-Volt fixed linear regulator will be used and connected to the 12-volt rail
available on the SLB power connector. Power dissipation will be 78.4mW, which is
equivalent to rise in temperature of 20˚C above ambient.
2.5-Volt fixed linear regulators will be used and connected on the 3.3-volt rail
coming from the SLB power connector. Power dissipation of each regulator will be
22mW (VDD2) and 14.24mW (VIO), which is equivalent an increase in temperature of
respectively 5.6˚C and 3.6˚C above ambient.
No extra cooling should be required here.
The input stage is composed of 2 amplifiers (AD8021 from Analog Devices). Both
require symmetrical power supplies: +7 Volts and -7 Volts. TPS7A3001 and
TPS793001 regulators will be used. Less than 10mA will be drawn by each supply,
that’s 20mA in total per supply, generating a dissipation of 0.1 Watt (taken from a
12-volt input rail), equivalent to rise of temperature above ambient of 5.6˚C.
No extra cooling should be required here.