2

dc980abf

DEMO MANUAL

DC980A/DC980B

Glossary of terms

The following list contain terms used throughout the

document.

Channel: The collection of functions that monitor, super-

vise, and trim a given power supply rail.

Margin: Term used typically in board level testing that

increases/decreases the output voltage to look for sensi-

tivity/marginality problems.

Monitor: The act of measuring voltage, current, and tem-

perature readings.

Rail: The final output voltage that the power supply con-

troller manages.

Supervise: The act of quickly responding (warning or

faulting) to a voltage or current condition that is compared

to preprogrammed values.

Trim: The act of adjusting the final output voltage. A servo

loop is typically used to trim the voltage.

Table 1. LTC2970 Performance Summary

PARAMETER

CONDITIONS

VALUE

8V to 15V

4.5V to 5.75V

ADC Full-Scale Accuracy

±0.4%

ADC Total Unadjusted Error

±0.5%

ADC Input Range

0V to 6V

ADC Resolution

Resolution = 8.192V/16384

500µV/LSB

ADC Conversion Rate

30Hz

Margining DAC Resolution

8-Bits

Temperature Sensor Resolution

0.25°C/LSB

10kHz to 400kHz

Table 2. Demo Board System Specifications

NOMINAL

UNTRIMMED

TOP FEEDBACK

RESISTOR

BOTTOM

FEEDBACK

RESISTOR

DAC RESISTOR

IDAC

RESISTOR

MARGIN

RANGE

VOUT1

5V ±1.5%

105k

20k

147k

6.34k

±10%

VOUT2

3.3V ±1.5%

95.3k

30.1k

196k

6.34k

±10%

Notes:

1. Load current < 5A is recommended.

2. Output voltages can be margined by ±10% from nominal with the default resistor values. These values may be changed

to create output voltages other than 5V and 3.3V. Use the Resistor Selection Tool which is accessed from LTpowerPlay.

The LTC3828’s feedback node voltage is 0.8V.