EXAR MP8799AE

MP8799
CMOS
Very Low Power, 1 MSPS, 10-Bit
Analog-to-Digital Converter with 8-Channel Mux
FEATURES
BENEFITS
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
10-Bit Resolution
8-Channel Mux
Sampling Rates from <1 kHz to 1 MHz
Very Low Power CMOS - 30 mW (typ)
Power Down; Lower Consumption – 3 mW (typ)
Input Range between GND and VDD
No S/H Required for Analog Signals less than 100 kHz
No S/H Required for CCD Signals less than 1 MHz
Single Power Supply (4 to 6 Volts)
Latch-Up Free
High ESD Protection: 4000 Volts Minimum
3 V Version: MP87L99
Reduced Board Space (Small Package)
Reduced External Parts, No Sample/Hold Needed
Suitable for Battery & Power Critical Applications
Designer can Adapt Input Range & Scaling
APPLICATIONS
•
•
•
•
µP/DSP Interface and Control Applications
High Resolution Imaging – Scanners & Copiers
Wireless Digital Communications
Multiplexed Data Acquisition
GENERAL DESCRIPTION
Scaled reference resistor tap @ 1/4 R, 1/2 R and 3/4 R allows
for customizing the transfer curve as well as providing a 1/2 span
reference voltage. Digital outputs are CMOS and TTL
compatible.
The MP8799 is a flexible, easy to use, precision 10-bit
Analog-to-Digital Converter with 8-channel mux that operates
over a wide range of input and sampling conditions. The
MP8799 can operate with pulsed “on demand” conversion
operation or continuous “pipeline” operation for sampling rates
up to 1 MHz. The elimination of the S/H requirements, very low
power, and small package size offer the designer a low cost
solution. No sample and hold is required for charge couple
device applications up to 1 MHz, or multiplexed input
applications when the signal source bandwidth is limited to 100
kHz. The input architecture of the MP8799 allows direct
interface to any analog input range between AGND and AVDD (0
to 2 V, 1 to 4 V, 0 to 5 V, etc.). The user simply sets VREF(+) and
VREF(–) to encompass the desired input range.
The MP8799 uses a two-step flash technique. The first
segment converts the 4 MSBs and consists of 15 autobalanced
comparators, latches, an encoder, and buffer storage registers.
The second segment converts the remaining 6 LSBs.
When the power down input is “high”, the data outputs DB9 to
DB0 hold the current values and VREF(–) is disconnected from
VREF1(–). The power consumption during the power down mode
is approximately 3mW.
ORDERING INFORMATION
Package
Type
Temperature
Range
Part No.
DNL
(LSB)
INL
(LSB)
PQFP
–40 to +85°C
MP8799AE
1
2
Rev. 3.00
1
MP8799
SIMPLIFIED BLOCK AND TIMING DIAGRAM
AVDD
Coarse
Comparators
4
Adder
AVDD DVDD
φS
5
φB
VREF(+)
R3
Fine
Resolution
Comparators
R2
R1
VREF(–)
CLK
OFW
DB9-DB0
DFF
OE
Ladder
PD
VREF1(–)
CLK
φS
AIN1
1 or 8
MUX
AIN8
CLR
WR
A2
A1
A0
Latch
8
3 to 8
Decoder
AGND
DGND
PIN CONFIGURATIONS
See Packaging Section for
Package Dimensions
33
23
34
22
See the following
page for pin numbers
and descriptions
Index
44
12
1
11
44-Pin PQFP (10mm x 10mm)
QN44
Rev. 3.00
2
N
DB9-DB0
N-1
N
OFW
N-1
N
10
6
φB
MP8799
PIN OUT DEFINITIONS
PIN NO.
NAME
DESCRIPTION
PIN NO.
NAME
DESCRIPTION
1
DB6
Data Output Bit 6
23
R3
Reference Ladder Tap
2
DB7
Data Output Bit 7
24
N/C
No Connect
3
DGND
Digital Ground
25
AIN1
Analog Signal Input 1
4
DGND
Digital Ground
26
AIN2
Analog Signal Input 2
5
DVDD
Digital VDD
27
AIN3
Analog Signal Input 3
6
CLR
Clear (Active Low)
28
AIN4
Analog Signal Input 4
7
WR
Write (Active Low)
29
AIN5
Analog Signal Input 5
8
A2
Address 2
30
AGND
Analog Ground
9
A1
Address 1
31
AVDD
Analog VDD
10
A0
Address 0
32
AVDD
Analog VDD
11
CLK
Clock Input
33
AIN6
Analog Signal Input 6
12
OE
Output Enable (Active Low)
34
AGND
Analog Ground
13
N/C
No Connect
35
PD
Power Down
14
DB8
Data Output Bit 8
36
AIN7
Analog Signal Input 7
15
DB9
Data Output Bit 9 (MSB)
37
DB0
Data Output Bit 0 (LSB)
16
OFW
Overflow Output
38
DB1
Data Output Bit 1
17
VREF(+)
Upper Reference Voltage
39
DB2
Data Output Bit 2
18
VREF(–)
Lower Reference Voltage
40
DB3
Data Output Bit 3
19
VREF1(–)
Lower Reference Voltage
41
DB4
Data Output Bit 4
20
R1
Reference Ladder Tap
42
DB5
Data Output Bit 5
21
R2
Reference Ladder Tap
43
N/C
No Connect
22
AIN8
Analog Signal Input 8
44
N/C
No Connect
TRUTH TABLE FOR INPUT CHANNEL SELECTION
Selected
Analog Input
CLR
WR
A2
A1
A0
L
X
X
X
X
AIN1
H
L
L
L
L
AIN1
H
L
L
L
H
AIN2
H
L
L
H
L
AIN3
H
L
L
H
H
AIN4
H
L
H
L
L
AIN5
H
L
H
L
H
AIN6
H
L
H
H
L
AIN7
H
L
H
H
H
AIN8
H
H
X
X
X
Previous
Selection
Note: CLR, WR, A2, A1, A0 are internally connected to
ground through 500kΩ resistance.
Rev. 3.00
3
MP8799
ELECTRICAL CHARACTERISTICS TABLE
Unless Otherwise Specified: AVDD = DVDD = 5 V, FS = 1 MHz (50% Duty Cycle),
VREF(+) = 4.6, VREF(–) = AGND, TA = 25°C
Parameter
Symbol
Min
FS
10
.001
25°C
Typ
Max
Units
Test Conditions/Comments
1
Bits
MHz
For Rated Performance
+1
2
LSB
LSB
KEY FEATURES
Resolution
Sampling Rate
ACCURACY (A Grade)2
Differential Non-Linearity
Integral Non-Linearity
DNL
INL
Zero Scale Error
Full Scale Error
EZS
EFS
+0.50
–2.5
LSB
LSB
LSB
Best Fit Line
(Max INL – Min INL)/2
Reference from VREF(+) to VREF(–)
REFERENCE VOLTAGES
Positive Ref. Voltage
Negative Ref. Voltage
Differential Ref. Voltage5
Ladder Resistance
Ladder Temp. Coefficient1
Ladder Switch Resistance1
Ladder Switch Off Leakage1
VREF(+)
VREF(–)
VREF
RL
RTCO
AVDD
AGND
0.5
525
IILKG-SW
675
2000
12
50
AVDD
900
V
V
V
Ω
ppm/°C
Ω
nA
ANALOG INPUT1
Input Bandwidth
Input Voltage Range7
Input Capacitance3
Aperture Delay
100
VIN
CIN
tAP
VREF(–)
VIH
VIL
IIN
2.0
45
kHz
V
pF
ns
0.8
V
V
VREF(+)
60
35
DIGITAL INPUTS
Logical “1” Voltage
Logical “0” Voltage
Leakage Currents
CLK
PD, OE (Internal Res to DGND)
Input Capacitance
Clock Timing (See Figure 1.)1
Clock Period
Rise & Fall Time4
“High” Time6
“Low” Time6
+100
30
–5
5
TS
tR, tF
tB
tS
1000
10
500,000
500,000
250
150
Rev. 3.00
4
µA
µA
pF
ns
ns
ns
ns
VIN=DGND to DVDD
MP8799
ELECTRICAL CHARACTERISTICS TABLE (CONT’D)
25°C
Parameter
Symbol
Min
Typ
Max
Units
DIGITAL OUTPUTS
Logical “1” Voltage
Logical “0” Voltage
Tristate Leakage
Data Hold Time (See Figure 1.)1
Data Valid Delay1
Write Pulse Width1
Multiplexer Address Setup Time1
Multiplexer Address Hold Time1
Delay from WR to Multiplexer1
Enable
Power Down Time1
Power Up Time1
Test Conditions/Comments
COUT=15 pF
VOH
VOL
IOZ
tHLD
tDL
tWR
tAS
tAH
DVDD-0.5
0
30
35
0.4
+5
35
45
40
80
0
tMUXEN1
tPD
tPU
V
V
µA
ns
ns
ns
ns
ns
80
300
200
ns
ns
ns
1.2
6.5
10
mA
V
mA
ILOAD = 2 mA
ILOAD = 4 mA
VOUT = 0 to DVDD
POWER SUPPLIES8
Power Down (IDD)
Operating Voltage (AVDD, DVDD)
Current (AVDD + DVDD)
IPD-DD
VDD
IDD
4
0.6
5
6
VIN = 2 V
NOTES:
Guaranteed. Not tested.
Tester measures code transition voltages by dithering the voltage of the analog input (VIN). The difference between the measured
code width and the ideal value (VREF/1024) is the DNL error (see Figure 4.). The INL error is the maximum distance (in LSBs) from
the best fit line to any transition voltage (See Figure 7.).
3
See VIN input equivalent circuit (see Figure 9.).
4
Clock specification to meet aperture specification (tAP). Actual rise/fall time can be less stringent with no loss of accuracy.
5
Specified values guarantee functional device. Refer to other parameters for accuracy.
6
System can clock MP8799 with any duty cycle as long as all timing conditions are met.
7
Input range where input is converted correctly into binary code. Input voltage outside specified range converts to zero or full scale
output.
8
DVDD and AVDD are connected through the silicon substrate. Connect together at the package.
1
2
Specifications are subject to change without notice
ABSOLUTE MAXIMUM RATINGS (TA = +25°C unless otherwise noted)1, 2, 3
Storage Temperature . . . . . . . . . . . . . . . . . . . –65 to +150°C
VDD (to GND) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7 V
VREF(+), VREF(–), VREF1(–) . . . . . . . GND –0.5 to VDD +0.5 V
All AINs . . . . . . . . . . . . . . . . . . . . . . . GND –0.5 to VDD +0.5 V
All Inputs . . . . . . . . . . . . . . . . . . . . . GND –0.5 to VDD +0.5 V
All Outputs . . . . . . . . . . . . . . . . . . . GND –0.5 to VDD +0.5 V
Lead Temperature (Soldering 10 seconds) . . . . . . . +300°C
Package Power Dissipation Rating to 75°C
PQFP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450mW
Derates above 75°C . . . . . . . . . . . . . . . . . . . . . 14mW/°C
NOTES:
1
Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a
stress rating only and functional operation at or above this specification is not implied. Exposure to maximum rating
conditions for extended periods may affect device reliability.
2
Any input pin which can see a value outside the absolute maximum ratings should be protected by Schottky diode clamps
(HP5082-2835) from input pin to the supplies. All inputs have protection diodes which will protect the device from short
transients outside the supplies of less than 100mA for less than 100µs.
3
VDD refers to AVDD and DVDD. GND refers to AGND and DGND.
Rev. 3.00
5
MP8799
tR
tS
when φS disconnects the latches from the comparators. This delay is called aperture delay (tAP).
tF
tB
VIH
CLOCK
The coarse comparators make the first pass conversion and
selects a ladder range for the fine comparators. The fine comparators are connected to the selected range during the next φB
phase.
VIL
SAMPLE
N–1
AUTO
BALANCE
SAMPLE
N
AUTO
BALANCE
SAMPLE
N+1
φB
φS
TS
ANALOG
INPUT
φS
VIN
Latch
VOH
VTAP
DATA
N-1
Ref
Ladder
VOL
tDL
COARSE COMPARATOR
φB
φS
φS
tHLD
φB
VIN
Figure 1. MP8799 Timing Diagram
Latch
VTAP
THEORY OF OPERATION
Selected
Range
Analog-to-Digital Conversion
Figure 2. MP8799 Comparators
The MP8799 converts analog voltages into 1024 digital
codes by encoding the outputs of 15 coarse and 67 fine comparators. Digital logic is used to generate the overflow bit. The conversion is synchronous with the clock and it is accomplished in 2
clock periods.
AIN Sampling, Ladder Sampling, and Conversion Timing
Figure 3. shows this relationship as a timing chart. AIN sampling, ladder sampling and output data relationships are shown
for the general case where the levels which drive the ladder
need to change for each sampled AIN time point. The ladder is
referenced for both last AIN sample and next AIN sample at the
same time. If the ladder’s levels change by more than 1 LSB,
one of the samples must be discarded. Also note that the clock
low period for the discarded AIN can be reduced to the minimum
tS time of 150 ns.
The reference resistance ladder is a series of 1025 resistors.
The first and the last resistor of the ladder are half the value of
the others so that the following relations apply:
RREF = 1024 ∗ R
FINE COMPARATOR
φB
VREF = VREF(+) – VREF(–) = 1024 ∗ LSB
The clock signal generates the two internal phases, φB (CLK
high) and φS (CLK low = sample) (See Figure 2.). The rising
edge of the CLK input marks the end of the sampling phase (φS).
Internal delay of the clock circuitry will delay the actual instant
Hold Reference Value Past
Clock Change for tAP Time
Short Cycle Sample will be discarded
tS
External
Settle by Clock Update Time
Reference Stable Time – For Sample AIN2
Update
References
Reference Stable Time – For Sample AIN1
Clock
Internal
AIN Sample
Window
Ladder Sample
Window (MSB Bank)
Ladder Compare
(LSB Bank)
External
DATA
AINX1
Sample AIN1
S
B
AINX0
Sample AIN2
Not Used
B
Sample AIN1
S
S
B
AINX1
Sample AIN2
Sample Ladder
for AIN1
Sample Ladder
for AINX1
Sample Ladder
for AIN2
Sample Ladder
for AINX2
Compare Ladder
V/S AINX0
Compare Ladder
V/S AIN1
Compare Ladder
V/S AINX1
Compare Ladder
V/S AIN2
DATA AIN0
DATA AINX0
DATA AIN1
Not Used
Figure 3. AIN Sampling, Ladder Sampling & Conversion Timing
Rev. 3.00
6
DATA AINX1
Not Used
MP8799
Accuracy of Conversion: DNL and INL
DNL
LSB
V(N+1)
The transfer function for an ideal A/D converter is shown in
Figure 4.
Analog
Input
V(N)
DIGITAL
CODES
0.5 ∗ LSB
N+1
Output
Codes
0.5 ∗ LSB
N
N–1
OFW = 0
1 LSB
(N+1) Code Width = V(N+1) – V(N)
LSB = [ VREF(+) – VREF(–) ] / 1024
OFW = 1
3FF
3FE
001
000
002
DNL(N) = [ V(N+1) – V(N) ] – LSB
3FD
LSB
Figure 5. DNL Measurement
On Production Tester
V
VREF(–) V001
V002
V3FE
V3FF
V0FW VREF(+)
Figure 4. Ideal A/D Transfer Function
The formulas for Differential Non-linearity (DNL), Integral
Non-Linearity (INL) and zero and full scale errors (EZS, EFS) are:
The overflow transition (VOFW) takes place at:
DNL (001) = V002 – V001 – LSB
VIN = VOFW = VREF(+) – 0.5 ∗ LSB
: : :
The first and the last transitions for the data bits take place at:
DNL (3FE) = V3FF – V3FE – LSB
VIN = V001 = VREF(–) + 0.5 ∗ LSB
EFS (full scale error) = V3FF – [VREF(+) –1.5 ∗ LSB]
VIN = V3FF = VREF(–) – 1.5 ∗ LSB
EZS (zero scale error) = V001 – [VREF(–) + 0.5 ∗ LSB]
LSB = VREF / 1024 = (V3FF – V001) / 1022
DIGITAL
CODES
0.5 ∗ LSB
Note that the overflow transition is a flag and has no impact on
the data bits.
In a “real” converter the code-to-code transitions don’t fall
exactly every VREF/1024 volts.
1.5 ∗ LSB
EZS
EFS
3FF
A positive DNL (Differential Non-Linearity) error means that
the real width of a particular code is larger than 1 LSB. This error
is measured in fractions of LSBs.
002
3FE
001
000
A Max DNL specification guarantees that ALL code widths
(DNL errors) are within the stated value. A specification of Max
DNL = + 0.5 LSB means that all code widths are within 0.5 and
1.5 LSB. If VREF = 4.608 V then 1 LSB = 4.5 mV and every code
width is within 2.25 and 6.75 mV.
VREF(–)
V001
V002
V3FE
V
V3FF VREF(+)
Figure 6. Real A/D Transfer Curve
Figure 6. shows the zero scale and full scale error terms.
Rev. 3.00
7
MP8799
Figure 7. gives a visual definition of the INL error. The chart
shows a 3-bit converter transfer curve with greatly exaggerated
DNL errors to show the deviation of the real transfer curve from
the ideal one.
A system will clock the MP8799 continuously or it will give
clock pulses intermittently when a conversion is desired. The
timing of Figure 8a shows normal operation, while the timing of
Figure 8b keeps the MP8799 in balance and ready to sample the
analog input.
After a tester has measured all the transition voltages, the
computer draws a line parallel to the ideal transfer line. By definition the best fit line makes equal the positive and the negative
INL errors. For example, an INL error of –1 to +2 LSB’s relative
to the Ideal Line would be +1.5 LSB’s relative to the best fit line.
CLOCK
N
N+1
DATA
N
N+1
a. Continuous sampling
Output
Codes
Best Fit Line
7
CLOCK
N
BALANCE
Real Transfer Line
6
DATA
5
N
b. Single sampling
EFS
INL
4
Figure 8. Relationship of Data to Clock
Ideal Transfer Line
3
Analog Input
2
The MP8799 has very flexible input range characteristics.
The user may set VREF(+) and VREF(–) to two fixed voltages and
then vary the input DC and AC levels to match the VREF range.
Another method is to first design the analog input circuitry and
then adjust the reference voltages for the analog input range.
One advantage is that this approach may eliminate the need for
external gain and offset adjust circuitry which may be required
by fixed input range A/Ds.
LSB
1
Analog Input (Volt)
EZS
Figure 7. INL Error Calculation
The MP8799’s performance is optimized by using analog input circuitry that is capable of driving the AIN input. Figure 9.
shows the equivalent circuit for AIN.
Clock and Conversion Timing
40 Ω
AVDD
R Series
40W
AIN
15 pF
φS
R MUX
500W
4
1 pF
60 pF
87 pF
160 Ω
φS
10 pF
8
Control
87 pF
300 Ω
Channel
Selection
Figure 9. Analog Input Equivalent Circuit
Rev. 3.00
8
φB
+
4 pF
1/2 [ VREF(+)
+ VREF(–) ]
MP8799
Analog Input Multiplexer
Reference Voltages
The input/output relationship is a function of VREF:
The MP8799 includes a 8-Channel analog input multiplexer.
The relationship between the clock, the multiplexer address, the
WR and the output data is shown in Figure 10.
AIN = VIN – VREF(–)
VREF = VREF(+) – VREF(–)
DATA = 1023 ∗ (AIN/VREF)
A system can increase total gain by reducing VREF.
Digital Interfaces
Clock
Sample N
Old Address
Sample M
New Address
tCLKS2
tWR
Sample
M+1
tCLKH2
The logic encodes the outputs of the comparators into a binary code and latches the data in a D-type flip-flop for output.
tAH
The functional equivalent of the MP8799 (Figure 12.) is composed of:
WR
tAS
ÉÉ ÉÉÉÉÉÉÉÉÉÉ
ÉÉ ÉÉÉÉÉÉÉÉÉÉ
Delay stage (tAP) from the clock to the sampling phase
(φS).
An ideal analog switch which samples VIN.
An ideal A/D which tracks and converts VIN with no
delay.
A series of two DFF’s with specified hold (tHLD) and
delay (tDL) times.
1)
Address
DB0-DB9
N-2 Valid
N-1 Valid
Old Address
N Valid
Old Address
2)
3)
M Valid
New Address
4)
tCLKS2 = tCLKH2 = 0
Figure 10. MUX Address Timing
tAP, tHLD and tDL are specified in the Electrical Characteristics
table.
φS
VIN
tAS
D Q
D Q
DB9-DB0
tAH
tAP
A2, A1, A0
WR
A/D
CLK
MP8799
tWR
CLK
tMUXEN1
MUXEN
(Internal Signal)
N
VIN
N+1
tHLD
tDL
DB9-DB0
N-1
N
Figure 11. Analog MUX Timing
Figure 12. MP8799 Functional Equivalent
Circuit and Interface Timing
Rev. 3.00
9
MP8799
Power Down
Figure 13. shows the relationship between the clock,
sampled AIN to output data relationship and the effect of power
down.
CLK
SAMPLE
N
SAMPLE
M
VIN
DB0-DB9
N-2 Valid
N-1 Valid
N Valid
tCLKS1
SAMPLE
M+1
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
M Valid
tCLKH1
PD
tPD
tPU
IDD, IVREF(+)
Figure 13. Power Down Timing Diagram
Rev. 3.00
10
MP8799
APPLICATION NOTES
C1 = 4.7 or 10µF Tantalum
C2 = 0.1µF Chip Cap or low inductance cap
RT = Clock Transmission Line Termination
+5 V
C1A, C2A
AVDD
1 of 8
AIN
C1D, C2D
DVDD
Z 100W
Buffer
Resistive
Isolation of
50 to 100W
AIN1 (Substrate)
OFW
AIN8
DB9 - DB0
OE
MP8799
WR
CLK
Reference
Voltage
Source
VREF(+)
+
C1
–
C2
C1
CLK
3/4 R
C2
C1
1/4 R
C2
VREF(–)
VREF1(–)
AGND DGND
RT
A2
A1
A0
Figure 14. Typical Circuit Connections
The following information will be useful in maximizing the performance of the MP8799.
shield for parasitics and not a return path for signals. To reduce noise levels, use separate low impedance ground
paths. DGND should not be shared with other digital circuitry. If separate low impedance paths cannot be provided,
DGND should be connected to AGND next to the MP8799.
1. All signals should not exceed AVDD +0.5 V or AGND –0.5 V
or DVDD +0.5 V or DGND –0.5 V.
2. Any input pin which can see a value outside the absolute
maximum ratings (AVDD or DVDD+0.5 V or AGND –0.5 V)
should be protected by diode clamps (HP5082-2835) from
input pin to the supplies. All MP8799 inputs have input protection diodes which will protect the device from short transients outside the supply ranges.
7. DVDD should not be shared with other digital circuitry to
avoid conversion errors caused by digital supply transients.
DVDD for the MP8799 should be connected to AVDD next to
the MP8799.
8. DVDD and AVDD are connected inside the MP8799 through
the N – doped silicon substrate. Any DC voltage difference
between DVDD and AVDD will cause undesirable internal
currents.
3. The design of a PC board will affect the accuracy of MP8799.
Use of wire wrap is not recommended.
4. The analog input signal (VIN) is quite sensitive and should be
properly routed and terminated. It should be shielded from
the clock and digital outputs so as to minimize cross coupling
and noise pickup.
9. Each power supply and reference voltage pin should be
decoupled with a ceramic (0.1µF) and a tantalum (10µF) capacitor as close to the device as possible.
10. The digital output should not drive long wires. The capacitive
coupling and reflection will contribute noise to the conversion. When driving distant loads, buffers should be used.
100Ω resistors in series with the digital outputs in some applications reduces the digital output disruption of AIN.
5. The analog input should be driven by a low impedance (less
than 50Ω).
6. Analog and digital ground planes should be substantial and
common at one point only. The ground plane should act as a
Rev. 3.00
11
MP8799
+5 V
5k
0.1µF
+
MP5010
100k
+
–
–
Figure 15. Example of a Reference Voltage Source
+5 V
1 of 8
5 V
R
+5 V
R
VREF(+)
AVDD
+
VIN
DB0
AIN1
–
AIN8
VREF(–)
AGND
For R = 5k use Beckman Instruments #694-3-R10k resistor array or equivalent.
NOTE: High R values affect the input BW of ADC due to the (R ∗ CIN of ADC) time constant. Therefore, for different
applications the R value needs to be selected as a tradeoff between AIN settling time and power dissipation.
Figure 16. 5 V Analog Input
+5 V
1 of 8
10 V
2R
+5 V
R
VREF(+)
AVDD
+
VIN
DB0
AIN1
–
2R
AIN8
VREF(–)
AGND
For R = 5k use Beckman Instruments #694-3-R10k resistor array or equivalent.
NOTE: High R values affect the input BW of ADC due to the (R ∗ CIN of ADC) time constant. Therefore, for different
applications the R value needs to be selected as a tradeoff between AIN settling time and power dissipation.
Figure 17. 10 V Analog Input
Rev. 3.00
12
MP8799
MP8799
MP7641
DAC0
AIN1
DAC7
AIN8
+
–
VIN
+
–
VIN
MP7226
DAC4
VREF(+)
DAC3
3/4
DAC2
1/4
VREF(+)
DAC1
VREF1(–)
@ Power Down write values to DAC 3, 2, 1 = DAC 4 to minimize power consumption.
Only AIN and Ladder detail shown.
Figure 18. A/D Ladder and AIN with Programmed Control
(of VREF(+), VREF(–), 1/4 and 3/4 TAP.)
Rev. 3.00
13
MP8799
PERFORMANCE CHARACTERISTICS
Graph 1. DNL vs. Sampling Frequency
Graph 2. INL vs. Sampling Frequency
Graph 3. Supply Current vs.
Sampling Frequency
Graph 4. Power Down Current vs.
Sampling Frequency
Graph 5. DNL vs. Reference Voltage
Graph 6. DNL vs. Temperature
Rev. 3.00
14
MP8799
Graph 7. Supply Current vs.
Temperature
Graph 8. Power Down Current vs.
Temperature
Graph 9. Reference Resistance vs.
Temperature
Rev. 3.00
15
MP8799
44 LEAD PLASTIC QUAD FLAT PACK
(10mm X 10mm PQFP, METRIC)
QN44
D
D1
33
23
34
22
D1 D
44
12
1
11
B
e
A2
C
A
α
A1
L
MILLIMETERS
SYMBOL
A
INCHES
MIN
MAX
MIN
MAX
––
2.45
––
0.096
A1
0.25
––
0.01
––
A2
1.9
2.1
0.100
0.108
B
0.3
0.4
0.012
0.018
C
0.13
0.23
0.005
0.009
D
12.95
13.45
0.510
0.530
9.9
10.1
0.392
0.396
D1
e
0.8 BSC
0.0315 BSC
L
0.65
1.03
0.026
0.037
α
0°
7°
0°
7°
Coplanarity = 4 mil max.
Rev. 3.00
16
MP8799
Notes
Rev. 3.00
17
MP8799
Notes
Rev. 3.00
18
MP8799
Notes
Rev. 3.00
19
MP8799
NOTICE
EXAR Corporation reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are
free of patent infringement. Charts and schedules contains here in are only for illustration purposes and may vary
depending upon a user’s specific application. While the information in this publication has been carefully checked;
no responsibility, however, is assumed for inaccuracies.
EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or
malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly
affect its safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation
receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the
user assumes all such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances.
Copyright 1993 EXAR Corporation
Datasheet April 1995
Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.
Rev. 3.00
20