1.4V
3kΩ
D
OUT
100pF
C
LOAD
Test Point
D
OUT
t
r
t
f
V
OH
V
OL
Load Circuit for t
dDO
, t
r
, and t
f
Voltage Waveforms for D
OUT
Rise and Fall TImes t
r
, and t
f
Test Point
DCLOCK
V
IL
t
dDO
D
OUT
t
hDO
Voltage Waveforms for D
OUT
Delay Times, t
dDO
Load Circuit for t
dis
and t
den
V
OH
V
OL
D
OUT
3kΩ
100pF
C
LOAD
V
CC
t
dis
Waveform 2, t
en
t
dis
Waveform 1
CS/SHDN
V
IH
CS/SHDN
D
OUT
Waveform 1
(1)
t
dis
D
OUT
Waveform 2
(2)
Voltage Waveforms for t
dis
90%
DCLOCK
1
2
10%
D
OUT
t
en
V
OL
B11
NOTES: (1) Waveform 1 is for an output with internal conditions such that
the output is HIGH unless disabled by the output control. (2) Waveform 2
is for an output with internal conditions such that the output is LOW unless
disabled by the output control.
Voltage Waveforms for t
en
FIGURE 2. Timing Diagrams and Test Circuits for the Parameters in Table I.
DATA FORMAT
The output data from the ADS7816 is in Straight Binary
format as shown in Table II. This table represents the ideal
output code for the given input voltage and does not include
the effects of offset, gain error, or noise.
POWER DISSIPATION
The architecture of the converter, the semiconductor fabrica-
tion process, and a careful design allow the ADS7816 to
convert at up to a 200kHz rate while requiring very little
power. Still, for the absolute lowest power dissipation, there
are several things to keep in mind.
The power dissipation of the ADS7816 scales directly with
conversion rate. The first step to achieving the lowest power
dissipation is to find the lowest conversion rate that will
satisfy the requirements of the system.
In addition, the ADS7816 is in power down mode under two
conditions: when the conversion is complete and whenever
CS is HIGH (see Figure 1). Ideally, each conversion should
occur as quickly as possible, preferably, at a 3.2MHz clock
rate. This way, the converter spends the longest possible
time in the power down mode. This is very important as the
DESCRIPTION
Full Scale Range
Least Significant
Bit (LSB)
Full Scale
Midscale
Midscale – 1 LSB
Zero
ANALOG VALUE
V
REF
V
REF
/4096
V
REF
–1 LSB
V
REF
/2
V
REF
/2 – 1 LSB
0V
DIGITAL OUTPUT:
STRAIGHT BINARY
BINARY CODE
1111 1111 1111
1000 0000 0000
0111 1111 1111
0000 0000 0000
HEX CODE
FFF
800
7FF
000
Table II. Ideal Input Voltages and Output Codes.
®
ADS7816
10
BURR-BROWN [ BURR-BROWN CORPORATION ]
