MICRO-LINEAR ML2259BCQ

May 1997
ML2252*, ML2259**
µP Compatible 8-Bit A/D Converters
with 2- or 8-Channel Multiplexer
GENERAL DESCRIPTION
FEATURES
The ML2252 and ML2259 combine an 8-bit A/D
converter, 2- or 8-channel analog multiplexer, and a
microprocessor compatible 8-bit parallel interface and
control logic in a single monolithic CMOS device.
■
Easy interface to microprocessors is provided by the
latched and decoded multiplexer address inputs and a
double buffered three-state data bus. These analog-todigital converters allow the microprocessor to operate
completely asynchronous to the converter clock.
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■
■
■
■
■
The built in sample and hold function provides the ability
to digitize a 5V, 50kHz sinewave to 8-bit accuracy. The
differential comparator design provides low power supply
sensitivity to DC and AC variations. The voltage reference
can be externally set to any value between ground and
VCC, thus allowing a full conversion over a relatively
small span. All parameters are guaranteed over
temperature with a power supply voltage of 5V ±10%.
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■
■
■
■
■
The device is suitable for a wide range of applications
from process and machine control to consumer,
automotive, and telecommunication applications.
* This Part Is Obsolete
ML2252 BLOCK DIAGRAM
** This Part Is End of Life As Of August 1, 2000
VCC
START
CLOCK
CH0
CH1
Conversion time (fCLK = 1.46MHz); 6.6µs
Total unadjusted error; ±1/2LSB or ±1LSB
No missing codes
Sample and hold; 390ns acquisition
Capable of digitizing a 5V, 50kHz sinewave
2- or 8-channel input multiplexer
0V to 5V analog input range with single 5V
power supply
Operates ratiometrically or with up to 5V
voltage reference
No zero or full scale adjust required
Analog input protection; 25mA per input min
Continuous conversion mode
Low power dissipation; 15mW max
TTL and CMOS compatible digital inputs and outputs
EOC
CONTROL
& TIMING
2-CHANNEL
MULTIPLEXER
+
8pF
–
+
COMP
–
DB0
SUCCESSIVE
APPROXIMATION
REGISTER
A/D WITH
SAMPLE-AND-HOLD FUNCTION
A0
GND
DB1
DB2
THREE
STATE
OUTPUT
BUFFER
8pF
ADDRESS
LATCH
AND
DECODER
ALE
Σ
DB5
DB6
D/A
CONVERTER
+VREF
DB3
DB4
DB7
–VREF
OE
1
ML2252, ML2259
ML2259 BLOCK DIAGRAM
VCC
CLK
CH0
START
CH1
CONTROL
& TIMING
CH2
CH3
EOC
8-CHANNEL
MULTIPLEXER
+
CH5
CH6
8pF
CH7
DB1
DB2
THREE
STATE
OUTPUT
BUFFER
A/D WITH
SAMPLE-AND-HOLD FUNCTION
A2
GND
DB4
DB5
DB6
D/A
CONVERTER
+VREF
DB3
DB7
OE
–VREF
PIN CONFIGURATION
3
18
ALE
DB3
4
17
DB7
OE
5
16
DB6
ADDR0
ADDR0
EOC
3
2
1
20
19
DB3
4
18
ALE
OE
5
17
DB7
CLK
6
16
DB6
15
DB5
14
DB4
CLK
6
15
DB5
VCC
7
14
DB4
VCC
7
+VREF
8
13
DB0
+VREF
8
GND
9
12
–VREF
DB1
10
11
DB2
TOP VIEW
9
10 11
12
13
DB0
CH0
19
CH0
20
2
–VREF
1
DB2
CH1
START
CH1
ML2252
20-Pin DIP (P20)
START
ML2252
20-Pin PLCC (Q20)
EOL
A1
SUCCESSIVE
APPROXIMATION
REGISTER
DB1
A0
–
+
COMP
–
8pF
ADDRESS
LATCH
AND
DECODER
ALE
DB0
Σ
GND
CH4
TOP VIEW
ML2259
28-Pin DIP(P28W)
CH0
CH6
4
25
ADDR0
CH0
26
CH1
3
CH2
CH1
CH5
CH3
CH2
27
CH4
28
2
CH5
1
CH4
CH6
CH3
4
3
2
1
28
27
26
25
CH7
5
ADDR0
START
6
24
ADDR1
23
ADDR2
EOC
7
23
ADDR2
7
22
ALE
DB3
8
22
ALE
DB3
8
21
DB7
OE
9
OE
DB7
20
DB6
21
9
CLK
10
20
DB6
VCC
11
12
DB5
10
19
DB5
VCC
11
18
DB4
+VREF
12
17
DB0
GND
13
16
–VREF
DB1
14
15
DB2
13 14
15
16
17
19
18
DB1
CLK
DB4
6
EOC
DB0
START
–VREF
ADDR1
DB2
24
GND
5
+VREF
CH7
TOP VIEW
2
ML2259
28-Pin PLCC (Q28)
TOP VIEW
ML2252, ML2259
PIN DESCRIPTION
Pin Number
ML2252 ML2259
Name
Function
2
3
1
2
3
4
5
6
7
CH3
CH4
CH5
CH6
CH7
START
EOC
4
5
8
9
DB3
OE
6
10
CLK
7
8
9
11
12
13
VCC
+VREF
GND
10
11
12
13
14
15
16
17
18
14
15
16
17
18
19
20
21
22
DB1
DB2
–VREF
DB0
DB4
DB5
DB6
DB7
ALE
23
24
25
26
27
28
ADDR2
ADDR1
ADDR0
CH0
CH1
CH2
Analog input 3.
Analog input 4.
Analog input 5.
Analog input 6.
Analog input 7.
Start of conversion. Active high digital input pulse initiates conversion.
End of conversion. This output goes low after a START pulse occurs, stays
low for the entire A/D conversion, and goes high after conversion is
completed. Data on DB0–DB7 is valid on rising edge of EOC and stays valid
until next EOC rising edge.
Data output 3.
Output enable input. When OE = 0, DB0–DB7 are in high impedance state;
OE = 1, DB0–DB7 are active outputs.
Clock. Clock input provides timing for A/D converter, S/H, and digital
interface.
Positive supply. 5V ±10%.
Positive reference voltage.
Ground. 0V, all analog and digital inputs or outputs are referenced to this
point.
Data output 1.
Data output 2.
Negative reference voltage.
Data output 0.
Data output 4.
Data output 5.
Data output 6.
Data output 7.
Address latch enable. Input to latch in the digital address (ADDR2-0) on the
rising edge of the multiplexer.
Address input 2 to multiplexer. Digital input for selecting analog input.
Address input 1 to multiplexer. Digital input for selecting analog input.
Address input 0 to multiplexer. Digital input for selecting analog input.
Analog input 0.
Analog input 1.
Analog input 2.
19
20
1
3
ML2252, ML2259
ABSOLUTE MAXIMUM RATINGS
Absolute maximum ratings are those values beyond which
the device could be permanently damaged. Absolute
maximum ratings are stress ratings only and functional
device operation is not implied.
Thermal Resistance (qJA)
20-Pin PDIP ..................................................... 67°C/W
20-Pin PLCC .................................................... 78°C/W
28 Pin PDIP ..................................................... 48°C/W
28-Pin PLCC .................................................... 68°C/W
Supply Voltage, VCC .............................................................. 6.5V
Logic Inputs ....................................... –0.3V to VCC 0.3V
Analog Inputs ..................................... –0.3V to VCC 0.3V
Input Current per Pin ............................................ ±25mA
Storage Temperature ................................ –65°C to 150°C
Lead Temperature (Soldering 10 sec.) .................... 260°C
OPERATING CONDITIONS
Supply Voltage, VCC .............................................. 4.5V to 6.3V
Temperature Range ........................................ 0°C to 70°C
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, VCC = +VREF = 5V ±10%, –VREF = GND, fCLK = 1.46MHz,
TA = Operating temperature range (Note 1)
ML2252B, ML2259B
PARAMETER
CONDITIONS
MIN
TYP
ML2252C, ML2259C
MAX
MIN
TYP
MAX
UNITS
±1
LSB
Converter and Multiplexer Characteristics
Total Unadjusted Error
VREF = VCC, (Note 2)
±1/2
+VREF Voltage Range
–VREF
VCC + 0.1
–VREF
VCC + 0.1
V
–VREF Voltage Range
GND – 0.1
+VREF
GND – 0.1
+VREF
V
35
14
28
ký
VCC + 0.1
V
±1/4
LSB
Reference Input Resistance
14
20
Analog Input Range
(Note 3)
Power Supply Sensitivity
DC, VCC = 5V ±10%
±1/32
100mVp-p, 100kHz
Sine on VCC, VIN = 0
±1/16
IOFF, Off Channel Leakage
Current (Note 9)
GND – 0.1
On Channel = VCC, (Note 4)
Off Channel = 0V
VCC + 0.1 GND – 0.1
On Channel = 0V, (Note 4)
Off Channel = VCC
PARAMETER
±1/32
±1/16
LSB
–1
µA
1
1
–1
On Channel = VCC, (Note 4)
Off Channel = 0V
SYMBOL
±1/4
–1
On Channel = 0V, (Note 4)
Off Channel = VCC
ION, On Channel Leakage
Current (Note 9)
20
–1
µA
1
CONDITIONS
µA
1
MIN
TYP
MAX
µA
UNITS
Digital and DC
VIN(1)
Logical “1” Input Voltage
2.0
V
VIN(0)
Logical “0” Input Voltage
IIN(1)
Logical “1” Input Current
VIN = VCC
IIN(0)
Logical “0” Input Current
VIN = 0V
–1
µA
VOUT(1)
Logical “1” Output Voltage
IOUT = –2mA
4.0
V
VOUT(0)
Logical “0” Output Voltage
IOUT = 2mA
IOUT
Three-State Output Current
VOUT = 0V
4
Supply Current
V
1
µA
0.4
–1
V
µA
VOUT = VCC
ICC
0.8
1.5
1
µA
3
mA
ML2252, ML2259
ELECTRICAL CHARACTERISTICS
SYMBOL
(Continued)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
AC and Dynamic Performance Characteristics (Note 5)
tACQ
Sample and Hold Acquisition
1/2
fCLK
Clock Frequency
tC
Conversion Time
SNR
Signal to Noise Ratio
VIN = 51kHz, 5V sine.
fCLK = 1.46MHz
(fSAMPLING > 150kHz). Noise is sum
of all nonfundamental components
up to 1/2 of fSAMPLING
47
dB
THD
Total Harmonic Distortion
VIN = 51kHz, 5V sine.
fCLK = 1.46MHz
(fSAMPLING > 150kHz).
THD is sum 2, 3, 4, 5 harmonics
relative to fundamental
–60
dB
IMD
Intermodulation Distortion
VIN = fA + fB. fA = 49kHz, 2.5V sine.
fB = 47.8kHz, 2.5V sine,
fCLK = 1.46MHz
(fSAMPLING > 150kHz). IMD is (fA + fB),
(fA – fB), (2fA + fB), (2fA – fB), (fA + 2fB),
(fA – 2fB) relative to fundamental
–60
dB
FR
Frequency Response
VIN = 0 to 50kHz. 5V sine relative
to 1kHz
0.1
dB
tDC
Clock Duty Cycle
(Note 6)
tEOC
End of Conversion Delay
tWS
Start Pulse Width
tSS
Start Pulse Setup Time
tWALE
10
8.5
40
1/2
1/fCLK
1460
kHz
8.5 + 250ns
1/fCLK
60
%
1/2 + 250ns
1/fCLK
50
ns
40
ns
Address Latch Enable
Pulse Width
50
ns
tS
Address Setup
0
ns
tH
Address Hold
50
ns
tH1, H0
Output Enable for DB0–DB7
t1H, 0H
Output Disable for DB0–DB7
CIN
Capacitance of Logic Input
COUT
Capacitance of Logic Outputs
Synchronous only, (Note 7)
Figure 1, CL = 50pF
100
ns
Figure 1, CL = 10pF
50
ns
Figure 1, CL = 50pF
100
ns
Figure 1, CL = 10pF
50
ns
5
pF
10
pF
Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst-case test conditions.
Note 2: Total unadjusted error includes offset, full scale, linearity, multiplexer and sample and hold errors.
Note 3: For –VREF • VIN (+) the digital output code will be 0000 0000. Two on-chip diodes are tied to each analog input which will forward conduct for analog input voltages
one diode drop below ground or one diode drop greater than the VCC supply. Be careful, during testing at low VCC levels (4.5V), as high level analog inputs (5V) can
cause this input diode to conduct — especially at elevated temperatures, and cause errors for analog inputs near full scale. The spec allow 100mV forward bias of either
diode. This means that as long as the analog VIN or VREF does not exceed the supply voltage by more than 100mV, the output code will be correct. To achieve an
absolute 0VDC to 5VDC input voltage range will therefore require a minimum supply voltage of 4.900VDC over temperature variations, initial tolerance and loading.
Note 4: Leakage current is measured with the clock not switching.
Note 5: CL = 50pF, timing measured at 50% point.
Note 6: A 40% to 60% clock duty cycle range insures proper operation at all clock frequencies. In the case that an available clock has a duty cycle outside of these limits,
the minimum time the clock is high or the minimum time the clock is low must be at least 40ns. The maximum time the clock can be high or low is 60µs.
Note 7: The conversion start setup time requirement only needs to be satisfied if a conversion must be synchronized to a given clock rising edge. If the setup time is not met,
start conversion will have an uncertainty of one clock pulse.
5
ML2252, ML2259
tr
tf
OUTPUT
ENABLE
DATA
OUTPUT
VCC
GND
90%
50%
10%
10k
CL
90%
t1H
VOH
50%
10%
t0H
90%
50%
OUTPUT
GND
VCC
tf
OUTPUT
ENABLE
10k
DATA
OUTPUT
VCC
GND
tr
90%
90%
50%
10%
t0H
VCC
CL
OUTPUT
VOL
50%
10%
Figure 1. High Impedance Test Circuits and Waveforms
TYPICAL PERFORMANCE CURVES
1.0
VCC = 5V
VREF = 5V
LINEARITY ERROR (LSB)
0.75
0.5
0.25
25°C
0
0.001
0.01
0.1
CLOCK FREQUENCY (MHz)
Figure 2. Linearity Error vs fCLK
6
50%
10%
tH0
1.0
ML2252, ML2259
TYPICAL PERFORMANCE CURVES (Continued)
2
1
VCC = 5V
VIN = 0V
fCLK = 1.46MHz
TA = 25°C
VCC = 5V
fCLK = 1.46MHz
1.5
OFFSET ERROR (LSB)
LINEARITY ERROR (LSB)
0.75
0.5
25°C
1
0.5
0.25
0
0
0
1
2
3
4
5
0
1
2
3
4
5
VREF (VDC)
VREF (VDC)
Figure 4. Unadjusted Offset Error vs VREF Voltage
Figure 3. Linearity Error vs VREF Voltage
1.0 FUNCTIONAL DESCRIPTION
1.1 MULTIPLEXER ADDRESSING
1.2 A/D CONVERTER
The ML2252 and ML2259 contain a single ended analog
multiplexer. A particular input channel is selected by
using the address decoder. The relationship between the
address inputs, ADDR0–ADDR2, and the analog input
selected is shown in Table 1. The address inputs are
latched into the decoder on the rising edge of the address
latch signal ALE.
The A/D converter uses successive approximation to
perform the conversion. The converter is composed of the
successive approximation register, the DAC and the
comparator.
ML2252
SELECTED
ANALOG CHANNEL
ADDRESS
INPUT
CH0
0
CH1
1
ML2259
SELECTED
ANALOG CHANNEL
ADDRESS INPUT
ADDR2
ADDR1
ADDR0
CH0
0
0
0
CH1
0
0
1
CH2
0
1
0
CH3
0
1
1
CH4
1
0
0
CH5
1
0
1
CH6
1
1
0
CH7
1
1
1
The DAC generates the precise levels that determine the
linearity and accuracy of the conversion. The DAC is
composed of a capacitor upper array and a resistor lower
array. The capacitor upper array generates the 4 MSB
decision levels while the series resistor lower array
generates the 4 LSB decision levels. A switch decoder tree
is used to decode the proper level from both arrays.
The capacitor/resistor array offers fast conversion, superior
linearity and accuracy since matching is only required
between 24 = 16 elements (as opposed to 28 = 256
elements in conventional designs). And since the levels are
based on the ratio of capacitors to capacitors and resistors to
resistors, the accuracy and long term stability of the
converter is improved. This also guarantees monotonicity
and no missing codes, as well as eliminating any linearity
temperature or power supply dependence.
The successive approximation register is a digital block
used to store the bit decisions from the conversion.
The comparator design is unique in that it is fully
differential and auto zeroed. The fully differential
architecture provides excellent noise immunity, excellent
power supply rejection, and wide common mode range. The
comparator is auto zeroed at the start of each conversion in
order to remove any DC offset and full scale gain error, thus
improving accuracy and linearity.
Table 1. Multiplexer Address Decoding
7
ML2252, ML2259
Another advantage of the capacitor array approach used in
the ML2252 and ML2259 is the inherent sample-and-hold
function. This true S/H allows an accurate conversion to be
done on the input even if the analog signal is not stable.
Linearity and accuracy are maintained for analog signals up
to 1/2 the sampling frequency. As a result, input signals up
to 50kHz can be converted without degradation in linearity
or accuracy.
The sequence of events during a conversion is shown in
figure 5. The rising edge of a START pulse resets the internal
registers and initiates a conversion on the next rising edge
of CLK providing that (tSS) start pulse setup time is satisfied.
If this setup time is not met, start conversion will have an
uncertainty of one clock pulse. The input is then sampled for
the next half CLK period until EOC goes low. EOC goes low
on the falling edge of the next CLK pulse indicating that the
conversion is now beginning. The actual conversion now
takes place for the next eight CLK pulses, one bit for each
CLK pulse. After the conversion is done, the data is updated
on DB0–DB7 and EOC goes high on the rising edge of the
9th CLK pulse, indicating that the conversion has been
completed and data is valid on DB0–DB7. The data will
stay valid on DB0–DB7 until the next conversion updates
the data word on the next rising edge of EOC.
A conversion can be interrupted and restarted at any time
by a new START pulse.
1.3 ANALOG INPUTS AND SAMPLE/HOLD
The ML2252 and ML2259 have a true sample-and-hold
circuit which samples both the selected input and ground
simultaneously. These analog to digital converters can
reject AC common mode signals from DC–50kHz as well
as maintain linearity for signals from DC–50kHz.
The plot in Figure 6 shows a 2048 point FFT of the
ML2259 converting a 50kHz, 0 to 5V, low distortion sine
wave input. The ML2252 and ML2259 sample and
digitize, at their specified accuracy, dynamic input
signals with frequency components up to the Nyquist
frequency (one-half the sampling rate). The output spectra
yields precise measurements of input signal level, harmonic
components, and signal to noise ratio up to the 8-bit level.
The near ideal signal to noise ratio is maintained
independent of increasing analog input frequencies to
50kHz.
The signal at the analog input is sampled during the
interval when the sampling switch is open prior to
conversion start. The sampling window (S/H acquisition
time) is one half CLK period long and occurs one half CLK
period after START goes low. When the sampling switch
closes at the start of the S/H acquisition time, 8pF of
capacitance is thrown onto the analog input. One half
CLK period later, the sampling switch opens, the signal
present at analog input is stored and conversion starts.
Since any error on the analog input at the end of the S/H
acquisition time will cause additional conversion error,
care should be taken to insure adequate settling and
charging time from the source. If more charging or
settling time is needed to reduce these analog input
errors, a longer CLK period can be used.
Each analog input has dual diodes to the supply rails, and
a minimum of ±25mA (±100mA typically) can be
injected into each analog input without causing latchup.
1/fCLK
CLK
1
2
3
4
5
6
7
8
9
tSS
START
tWS
ALE
tWALE
ADDR0–ADDR2
tS
tH
tEOC
EOC
tC
DB0–DB7
PREVIOUS DATA
DATA
tHI, tHO
tIH, tOH
OE
Figure 5. Timing Diagram
8
ML2252, ML2259
1.4 REFERENCE
1.5 POWER SUPPLY AND REFERENCE DECOUPLING
The voltage applied to the +VREF and –VREF inputs
defines the voltage span of the analog input (the
difference between VINMAX and VINMIN) over which the
256 possible output codes apply. The devices can be used
in either ratiometric applications or in systems requiring
absolute accuracy. The reference pins must be connected
to a voltage source capable of driving the reference input
resistance, typically 20k.
A 10µF electrolytic capacitor is recommended to bypass
VCC to GND, using as short a lead length as possible. In
addition, with clock frequencies above 1MHz, a 0.1µF
ceramic disc capacitor should be used to bypass VCC to
GND.
In a ratiometric system, the analog input voltage is
proportional to the voltage used for the A/D reference.
This voltage is typically the system power supply, so the
+VREF pin can be tied to VCC and –VREF tied to GND. This
technique relaxes the stability requirements of the system
reference as the analog input and A/D reference move
together maintaining the same output code for a given
input condition.
For absolute accuracy, where the analog input varies
between specific voltage limits, the reference pins can be
biased with a time and temperature stable voltage source.
+VREF and –VREF can be at any voltage between VCC and
GND. In addition, the difference between +VREF and
–VREF can be set to small values for conversions over
smaller voltage ranges. Particular care must be taken with
regard to noise pickup, circuit layout ond system error
voltage sources when operating with a reduced span due
to the increased sensitivity converter.
If REF+ and REF– inputs are driven by long lines, they
should be bypassed by 0.1µF ceramic disc capacitors at
the reference input pins (pins 12, 16).
1.6 DYNAMIC PERFORMANCE
Signal-to-Noise Ratio
Signal-to-noise ratio (SNR) is the measured signal to noise
at the output of the converter. The signal is the rms
magnitude of the fundamental. Noise is the rms sum of all
the nonfundamental signals up to half the sampling
frequency. SNR is dependent on the number of
quantization levels used in the digitization process; the
more levels, the smaller the quantization noise. The
theoretical SNR for a sine wave is given by
SNR = (6.02N + 1.76)dB
where N is the number of bits. Thus for ideal 8-bit
converter, SNR = 49.92dB.
Harmonic Distortion
Harmonic distortion is the ratio of the rms sum of
harmonics to the fundamental. Total harmonic distortion
(THD) of the ML2252 and ML2259 are defined as
2
20log
2
2
2
1/ 2
(V2 + V3 + V4 + V5 )
V1
where V1 is the rms amplitude of the fundamental and V2,
V3, V4, V5 are the rms amplitudes of the individual
harmonics.
0
–10
–20
MAGNITUDE (dB)
–30
–40
–50
–60
–70
–80
–90
–100
–110
37.5
FREQUENCY (kHz)
75
Figure 6. Output Spectrum
9
ML2252, ML2259
Intermodulation Distortion
With inputs consisting of sine waves at two frequencies,
fA and fB, any active device with nonlinearities will
create distortion products, of order (m + n), at sum and
difference frequencies of mfA + nfB, where m, n = 0, 1, 2,
3,... . Intermodulation terms are those for which m or n is
not equal to zero. The (IMD) intermodulation distortion
specification includes the second order terms (fA + fB) and
(fA – fB) and the third order terms (2fA + fB), (2fA – fB),
(fA + 2fB) and (fA – 2fB) only.
1.7 DIGITAL INTERFACE
The analog inputs are selected by the digital addresses,
ADDR0–ADDR2, and latched on the rising edge of ALE.
This is described in the Multiplexer Addressing section.
A conversion is initiated by the rising edge of a START
pulse. As long as this pulse is high, the internal logic is
reset.
The signal OE drives the data bus, DB0–DB7, into the
high impedance state when held low. This allows the
ML2252 and ML2259 to be tied directly to a µP system
bus without any latches or buffers.
1.7.1 Restart During Conversion
If the A/D is restarted (start goes low and returns high)
during a convesion, the converter is reset and a new
conversion is started. The output data latch is not updated
if the conversion in process is not allowed to be
completed. EOC will remain low and the output data
latch is not updated.
1.7.2 Continuous Conversions
In the free-running, continuous conversion mode, the start
input is tied to the (figure 7) EOC output. An initialization
pulse, following power-up, of mementarily forcing a logic
high level is required to guarantee operation.
The sampling interval starts with the following CLK rising
edge after a START falling edge and ends on the falling
edge of CLK. The conversion starts and EOC goes low. The
sampling clock is at least one half CLK period wide. Each
bit conversion in the successive approximation process
takes 1 CLK period. On the rising edge of the ninth CLK
pulse, the digital output of the conversion is updated on
the outputs DB0–DB7 and EOC goes high indicating the
conversion is done and data on DB0–DB7 is valid.
ML2252
ML2259
VCC
START
EOC
One feature of the ML2252 and ML2259 is that the data is
double buffered. This means that the outputs DB0–DB7
will stay valid until updated at the end of the next
conversion and will not become invalid when the next
conversion starts. This facilitates interfacing with external
logic of µP.
START
Figure 7. Continuous Conversion Mode
2.0 TYPICAL APPLICATIONS
VCC (5VDC)
4k
15VDC
–
VCC
1k
+
600Ω
–
ANALOG
IN
FS
ADJ
VCC
ML2252
ML2259
VCC
+
0.85VCC
ML2252
ML2259
24k
+
–15VDC
+VREF
+
10µF
10µF
XDR
CH
20k
–
GND
–VREF
1k
+
ZERO ADJ
0.15VCC
3k
Figure 8. Protecting the Input
10
Figure 9. Operating with Ratiometric Transducers 15% of
VCC - VXDR - 85% of VCC
ML2252, ML2259
PHYSICAL DIMENSIONS
inches (millimeters)
Package: P20
20-Pin PDIP
1.010 - 1.035
(25.65 - 26.29)
20
0.240 - 0.260 0.295 - 0.325
(6.09 - 6.61) (7.49 - 8.26)
PIN 1 ID
0.060 MIN
(1.52 MIN)
(4 PLACES)
1
0.055 - 0.065
(1.40 - 1.65)
0.100 BSC
(2.54 BSC)
0.015 MIN
(0.38 MIN)
0.170 MAX
(4.32 MAX)
SEATING PLANE
0.016 - 0.022
(0.40 - 0.56)
0.125 MIN
(3.18 MIN)
0.008 - 0.012
(0.20 - 0.31)
0º - 15º
Package: Q20
20-Pin PLCC
0.385 - 0.395
(9.78 - 10.03)
0.042 - 0.056
(1.07 - 1.42)
0.350 - 0.356
(8.89 - 9.04)
0.025 - 0.045
(0.63 - 1.14)
(RADIUS)
1
0.042 - 0.048
(1.07 - 1.22)
6
PIN 1 ID
16
0.350 - 0.356
(8.89 - 9.04)
0.385 - 0.395
(9.78 - 10.03)
0.200 BSC
(5.08 BSC)
0.290 - 0.330
(7.36 - 8.38)
11
0.009 - 0.011
(0.23 - 0.28)
0.050 BSC
(1.27 BSC)
0.026 - 0.032
(0.66 - 0.81)
0.165 - 0.180
(4.19 - 4.57)
0.146 - 0.156
(3.71 - 3.96)
0.100 - 0.110
(2.54 - 2.79)
0.013 - 0.021
(0.33 - 0.53)
SEATING PLANE
11
ML2252, ML2259
PHYSICAL DIMENSIONS
inches (millimeters) (Continued)
Package: P28W
28-Pin Wide PDIP
1.440 - 1.460
(36.57 - 37.09)
28
0.530 - 0.550 0.595 - 0.625
(13.46 - 13.97) (15.11 - 15.88)
PIN 1 ID
1
0.070 MIN
(1.77 MIN)
(4 PLACES)
0.050 - 0.065
(1.27 - 1.65)
0.100 BSC
(2.54 BSC)
0.015 MIN
(0.38 MIN)
0.190 MAX
(4.83 MAX)
0.016 - 0.022
(0.40 - 0.56)
0.125 MIN
(3.18 MIN)
SEATING PLANE
0.008 - 0.012
(0.20 - 0.31)
0º - 15º
Package: Q28
28-Pin PLCC
0.485 - 0.495
(12.32 - 12.57)
0.042 - 0.056
(1.07 - 1.42)
0.450 - 0.456
(11.43 - 11.58)
0.025 - 0.045
(0.63 - 1.14)
(RADIUS)
1
0.042 - 0.048
(1.07 - 1.22)
PIN 1 ID
8
22
0.300 BSC
(7.62 BSC)
0.450 - 0.456 0.485 - 0.495
(11.43 - 11.58) (12.32 - 12.57)
15
0.009 - 0.011
(0.23 - 0.28)
0.050 BSC
(1.27 BSC)
0.026 - 0.032
(0.66 - 0.81)
0.013 - 0.021
(0.33 - 0.53)
12
0.165 - 0.180
(4.06 - 4.57)
SEATING PLANE
0.148 - 0.156
(3.76 - 3.96)
0.099 - 0.110
(2.51 - 2.79)
0.390 - 0.430
(9.90 - 10.92)
ML2252, ML2259
ORDERING INFORMATION
PART NUMBER
TOTAL
UNADJUSTED ERROR
TEMPERATURE
RANGE
PACKAGE
Two Analog Inputs, 20-Pin Package
ML2252BCP (OBS)
ML2252BCQ (OBS)
ML2252CCP (OBS)
ML2252CCQ (OBS)
±1/2 LSB
±1 LSB
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
Molded DIP (P20)
Molded PLCC (Q20)
Molded DIP (P20)
Molded PLCC (Q20)
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
Molded DIP (Q28)
Molded PLCC (Q28)
Molded DIP (P28W)
Molded PLCC (Q28)
Eight Analog Inputs, 28-Pin Package
ML2259BCP (EOL)
ML2259BCQ (OBS)
ML2259CCP (OBS)
ML2259CCQ (OBS)
±1/2 LSB
±1 LSB
© Micro Linear 1997
is a registered trademark of Micro Linear Corporation
Products described in this document may be covered by one or more of the following patents, U.S.: 4,897,611; 4,964,026; 5,027,116; 5,281,862; 5,283,483; 5,418,502; 5,508,570; 5,510,727; 5,523,940; 5,546,017;
5,559,470; 5,565,761; 5,592,128; 5,594,376; Japan: 2598946; 2619299. Other patents are pending.
Micro Linear reserves the right to make changes to any product herein to improve reliability, function or
design. Micro Linear does not assume any liability arising out of the application or use of any product
described herein, neither does it convey any license under its patent right nor the rights of others. The
circuits contained in this data sheet are offered as possible applications only. Micro Linear makes no
warranties or representations as to whether the illustrated circuits infringe any intellectual property rights of
others, and will accept no responsibility or liability for use of any application herein. The customer is urged
to consult with appropriate legal counsel before deciding on a particular application.
2092 Concourse Drive
San Jose, CA 95131
Tel: 408/433-5200
Fax: 408/432-0295
DS2252_59-01
13