ADS8513 Datasheet, PDF (16/24 Pages) Texas Instruments – 16-BIT 40-KSPS LOW POWER SAMPLING ANALOG-TO-DIGITAL CONVERTER WITH INTERNAL REFERENCE AND PARALLEL/SERIAL INTERFACE

ADS8513
SLAS486 – JUNE 2007
POWER DOWN (continued)
POWER-DOWN TO POWER-UP RESPONSE
300
T_A = +25°C
250
200
150
100
50
0
0.1
1
10
100
Power-Down Duration (ms)
Figure 13. Power-Down to Power-Up Response
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1
2
3
4
+
1µF
0.01µF
1RF7604
8
7
6
5
1 R1_IN
2 GND
3 R2_IN
4 R3_IN
5 BUF
6 CAP
7 REF
8 GND
V_S 16
PWRD 15
BUSY 14
CS 13
CONV 12
EXT/INT 11
DATA 10
DATACLK 9
Figure 14. Improved Power-Up Response Circuit
Power-Down Signal
LAYOUT
POWER FOR TSSOP-20 PACKAGE
For optimum performance, tie the analog and digital power pins to the same +5-V power supply and tie the
analog and digital grounds together. As noted in the electrical characteristics, the ADS8507 uses 90% of its
power for the analog circuitry. The ADS8507 should be considered as an analog component.
The +5-V power for the A/D converter should be separate from the +5 V used for the system's digital logic.
Connecting +V_BD directly to a digital supply can reduce converter performance due to switching noise from the
digital logic. For best performance, the +5-V supply can be produced from whatever analog supply is used for the
rest of the analog signal conditioning. If +12-V or +15-V supplies are present, a simple +5-V regulator can be
used. Although it is not suggested, if the digital supply must be used to power the converter, be sure to properly
filter the supply. Either using a filtered digital supply or a regulated analog supply, both +V_BD and +V_A should be
tied to the same +5-V source.
GROUNDING
Two types of ground pins are present on the TSSOP package ADS8507. DGND is the digital supply ground.
AGND is the analog supply ground.
16
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