Datasheet ML2258BIP, ML2258BIQ, ML2258CIP, ML2258CIQ Datasheet (Micro Linear Corporation)

May 1997

ML2258*

µP Compatible 8-Bit A/D Converter

with 8-Channel Multiplexer

GENERAL DESCRIPTION

The ML2258 combines an 8-bit A/D converter, 8-channel
analog multiplexer, and a microprocessor compatible 8­bit parallel interface and control logic in a single
monolithic device.

Easy interface to microprocessors is provided by the
latched and decoded multiplexer address inputs and
latched three-state outputs.

The device is suitable for a wide range of applications
from process and machine control to consumer,
automotive, and telecommunication applications.

The ML2258 is an enhanced, pin-compatible, second
source for the industry standard ADC0808/ADC0809. The
ML2258 enhancements are faster conversion time, true
sample and hold function, superior power supply
rejection, wider reference range, and a double buffered
data bus as well as faster digital timing. All parameters
are guaranteed over temperature with a power supply
voltage of 5V ±10%.

BLOCK DIAGRAM

FEATURES

■ Conversion time 6.6µs

■ Total unadjusted error ±1/2LSB or ±1LSB

■ No missing codes

■ Sample and hold 390ns acquisition

■ Capable of digitizing a 5V, 50kHz sine wave

■ 8-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

■ Low power dissipation 3mA max

■ TTL and CMOS compatible digital inputs and outputs

■ Standard 28-pin DIP or surface mount PCC

■ Superior pin compatible replacement for ADC0808 and

ADC0809

* Some Packages Are End Of Life As Of August 1, 2000

START CLOCK

IN0

IN1

IN2

IN3

IN4

IN5

IN6

IN7

ADDR0
ADDR1

ADDR2

ADDRESS

LATCH ENABLE

8-CHANNEL

MULTIPLEXER

ADDRESS

LATCH

AND

DECODER

A/D WITH

SAMPLE HOLD

COMPARATOR

GNDV

CC

+V

CONTROL & TIMING

REF

S.A.R.

SWITCH TREE

CAPACITOR/

RESISTOR

ARRAY

–V

REF

THREE
STATE

OUTPUT

LATCH

BUFFER

OUTPUT

ENABLE

END OF CONVERSION
(INTERRUPT)

DB0
DB1
DB2
DB3
DB4
DB5
DB6
DB7

1

ML2258

PIN CONFIGURATION

ML2258

28-Pin DIP (P28)

IN3
IN4
IN5
IN6
IN7

START

EOC
DB3

OE
CLK
V

CC

+V

REF

GND

DB1

1

2

3

4

5

6

7

8

9

10

11

12

13

14

TOP VIEW

IN2

28

IN1

27

IN0

26

ADDR0

25

ADDR1

24

ADDR2

23

ALE

22

DB7

21

DB6

20

DB5

19

DB4

18

DB0

17

–V

16

15

REF

DB2

PIN DESCRIPTION

PIN# NAME FUNCTION

1 IN3 Analog input 3.
2 IN4 Analog input 4.
3 IN5 Analog input 5.
4 IN6 Analog input 6.
5 IN7 Analog input 7.
6 START Start of conversion. Active high digital

input pulse initiates conversion.

7 EOC 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.
8 DB3 Data output 3.
9 OE Output enable input. When OE = 0,

DB0–DB7 are in high impedance

state; OE = 1, DB0–DB7 are active

outputs.

10 CLK Clock. Clock input provides timing for

A/D converter, S/H, and digital

interface.

11 V
12 +V

CC

REF

Positive supply. 5V ± 10%.

Positive reference voltage.

ML2258

28-Pin PCC (Q28)

IN6

IN5

IN4

IN3

IN2

IN1

IN0

IN7

START

EOC

DB3

OE

CLK

V

432128

5

6

7

8

9

10

11

CC

12 13 14 15 16

REF

+V

GND

DB1

TOP VIEW

DB2

REF

–V

27 26

17 18

DB0

25

24

23

22

21

20

19

DB4

ADDR0

ADDR1

ADDR2

ALE

DB7

DB6

DB5

PIN# NAME FUNCTION

13 GND Ground. 0V, all analog and digital

inputs or outputs are reference to this

point.
14 DB1 Data output 1.
15 DB2 Data output 2.
16 –V

REF

Negative reference voltage.
17 DB0 Data output 0.
18 DB4 Data output 4.
19 DB5 Data output 5.
20 DB6 Data output 6.
21 DB7 Data output 7.
22 ALE Address latch enable. Input to latch in

the digital address (ADDR2–0) on the

rising edge of the multiplexer.
23 ADDR0 Address input 0 to multiplexer. Digital

input for selecting analog input.
24 ADDR1 Address input 1 to multiplexer. Digital

input for selecting analog input.
25 ADDR2 Address input 2 to multiplexer. Digital

input for selecting analog input.
26 IN0 Analog input 0.
27 IN1 Analog input 1.
28 IN2 Analog input 2.

2

ML2258

ABSOLUTE MAXIMUM RATINGS

(Note 1)
Supply Voltage, V

.............................................................. 6.5V

CC

Voltage

Logic Inputs .................................. –0.3V to VCC +0.3V

Analog Inputs ............................... –0.3V to VCC +0.3V

Input Current per Pin (Note 2) .............................. ±25mA

Storage Temperature ..............................–65°C to +150°C

Package Dissipation

at TA = 25°C (Board Mount) .............................875mW

Lead Temperature (Soldering 10 sec.)

Dual-In-Line Package (Plastic)............................ 260°C

ELECTRICAL CHARACTERISTICS

Unless otherwise specified, TA = T

PARAMETER NOTES CONDITIONS MIN (NOTE 4) MAX MIN (NOTE 4) MAX UNITS

Converter and Multiplexer

Total Unadjusted Error 5, 7 V
+V

Voltage Range 6 –V

REF

–V

Voltage Range 6 GND – 0.1 +V

REF

Reference Input Resistance 5 14 20 28 14 20 28 k ý
Analog Input Range 5, 8 GND – 0.1 VCC + 0.1 GND – 0.1 VCC + 0.1 V
Power Supply Sensitivity 6 DC, VCC = 5V ± 10% ±1/32 ±1/4 ±1/32 ±1/4 LSB

, Off Channel Leakage 5, 9 On Channel = V

I

OFF

Current (Note 9) Off Channel = 0V

ION, On Channel Leakage 5, 9 On Channel = 0V –1 –1 µA
Current (Note 9) Off Channel = V

Digital and DC

V

, Logical “1” Input 5 2.0 2.0 V

IN(1)

Voltage

, Logical “0” Input 5 0.8 0.8 V

V

IN(0)

Voltage
I

, Logical “1” Input 5 VIN = V

IN(1)

Current
I

, Logical “0” Input 5 VIN = 0V –1 –1 µA

IN(0)

Current
V

, Logical “1” 5 I

OUT(1)

Output Voltage

, Logical “0” 5 I

V

OUT(0)

Output Voltage
I

, Three-State Output 5 V

OUT

Current V

I

, Supply Current 5 1.5 3 1.5 3 mA

CC

MIN

to T

REF

, VCC = +V

MAX

= V

CC

REF

REF

100mVp-p, 100kHz ±1/16 ±1/16 LSB

sine on VCC, V

IN

= 0

CC

–1 –1 µA

On Channel = 0V 1 1 µA

Off Channel = V

On Channel = V

CC

CC

CC

Off Channel = 0V

CC

= –2mA 4.0 4.0 V

OUT

= 2mA 0.4 0.4 V

OUT

= 0V –1 –1 µA

OUT

= V

OUT

CC

Molded Chip Carrier Package

Vapor Phase (60 sec.) ..................................... 215°C

Infrared (15 sec.) ............................................ 220°C

OPERATING CONDITIONS

Supply Voltage, V

Temperature Range (Note 3) ................. T

ML2258BIP, ML2258BIQ, ML2258CIP,

ML2258CIQ ........................................ –40°C to +85°C

= 5V ±10%, –V

ML2258B ML2258C

TYP TYP

REF

±1/2 ±1 LSB

VCC + 0.1 –V

.................................... 4.5V

CC

MIN

= GND and f

GND – 0.1 +V

REF

CLK

REF

= 10.24MHz

VCC + 0.1 V

11µA

11µA

11µA

to 6.3V

DC

- TA - T

REF

MAX

V

DC

3

ML2258

ELECTRICAL CHARACTERISTICS

(Continued)

TYP

SYMBOL PARAMETER NOTES CONDITIONS MIN (NOTE 4) MAX UNITS

AC and Dynamic Performance Characteristics (Note 10)

t

ACQ

f

CLK

t

C

Sample and Hold Acquisition 4 1/f

CLK

Clock Frequency 5 100 10240 kHz
Conversion Time 5 67 67 + 250ns 1/f

CLK

SNR Signal to Noise Ratio VIN = 51kHz, 5V sine. 47 dB

= 10.24MHz

f

CLK

(f

SAMPLING

> 150kHz). Noise is sum
of all nonfundamental components
up to 1/2 of f

SAMPLING

THD Total Harmonic Distortion VIN = 51kHz, 5V sine. –60 dB

= 10.24MHz

f

CLK

(f

SAMPLING

> 150kHz). THD is sum
of 2, 3, 4, 5 harmonics relative to
fundamental

IMD Intermodulation Distortion V

= fA + fB. fA = 49kHz, 2.5V sine. –60 dB

IN

fB = 47.8kHz, 2.5V sine,

= 10.24MHz

f

CLK

(f

SAMPLING

> 150kHz). IMD is (fA + fB),
(fA – fB), (2fA + fB), (2fA – fB), (fA + 2fB),
(fA – 2fB) relative to fundamental

FR Frequency Response V

= 0 to 50kHz. 5V sine relative 0.1 dB

IN

to 1kHz

t

DC

t

EOC

t

WS

t

SS

t

WALE

t

S

t

H

t

H1, H0

Clock Duty Cycle 6, 11 40 60 %
End of Conversion Delay 5 8 8 + 250ns 1/f
Start Pulse Width 5 50 ns
Start Pulse Setup Time 6, 12 Synchronous only 40 ns
Address Latch Enable Pulse Width 5 50 ns
Address Setup 5 0 ns
Address Hold 5 50 ns
Output Enable for DB0–DB7 6 Figure 1, CL = 50pF 100 ns

CLK

6 Figure 1, CL = 10pF 50 ns

t

1H, 0H

Output Disable for DB0–DB7 6 Figure 1, CL = 50pF 200 ns

6 Figure 1, CL = 10pF 100 ns

C

IN

C

OUT

Note 1: Absolute maximum ratings are limits beyond which the life of the integrated circuit may be impaired. All voltages unless otherwise specified are measured with

Note 2: When the input voltage (V
Note 3: –40°C to +85°C operating temperature range devices are 100% tested with temperature limits guaranteed by 100% testing, sampling, or by correlation with worst-

Note 4: Typicals are parametric norm at 25°C.
Note 5: Parameter guaranteed and 100% production tested.
Note 6: Parameter guaranteed. Parameters not 100% tested are not in outgoing quality level calculation.
Note 7: Total unadjusted error includes offset, full scale, linearity, multiplexer and sample and hold errors.
Note 8: For –V

Note 9: Leakage current is measured with the clock not switching.
Note 10: C
Note 11: 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,

Note 12: 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,

Capacitance of Logic Input 5 pF
Capacitance of Logic Outputs 10 pF

respect to ground.

case test conditions.

• 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

REF

one diode drop below ground or one diode drop greater than the V
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 V
absolute 0V

= 50pF, timing measured at 50% point.

L

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.

start conversion will have an uncertainty of one clock pulse.

to 5VDC input voltage range will therefore require a minimum supply voltage of 4.900VDC over temperature variations, initial tolerance and loading.

DC

) at any pin exceeds the power supply rails (VIN < V– or VIN > V+) the absolute value of current at that pin should be limited to 25mA or less.

IN

supply. Be careful, during testing at low VCC levels (4.5V), as high level analog inputs (5V) can

CC

or V

does not exceed the supply voltage by more than 100mV, the output code will be correct. To achieve an

IN

REF

4

ML2258

DATA

OUTPUT

DATA

OUTPUT

C

L

t1H,t

t0H,t

10K

C

L

V

V

GND

V

OH

GND

V

GND

V

V

CC

CC

CC

OL

t1H,CL = 10pF

t

f

90%
50%
10%

t

1H

90%

t0H,CL = 10pF

t

f

90%
50%
10%

t

0H

10%

H1

OUTPUT

ENABLE

10K

OUTPUT

H0

CC

OUTPUT

ENABLE

OUTPUT

Figure 1. High Impedance Test Circuits and Waveforms

tH1,CL = 50pF

t

r

90%

50%

10%

t

0H

tH0,CL = 50pF

t

r

90%

50%

10%

t

H0

50%

50%

TYPICAL PERFORMANCE CURVES

1.0

0.75

0.5

LINEARITY ERROR (LSB)

0.25

–55 C

25 C

0

0.01 0.1 1.0 10

125 C

CLOCK FREQUENCY (MHz)

VCC = 5V
V

= 5V

REF

Figure 2. Linearity Error vs f

CLK

5

ML2258

TYPICAL PERFORMANCE CURVES (Continued)

1

0.75

0.5
125 C

LINEARITY ERROR (LSB)

0.25

–55 C

0

01 2 345

(VDC)

V

REF

VCC = 5V
f

= 10.4MHz

CLK

25 C

Figure 3. Linearity Error vs V

2

1.5

1

OFFSET ERROR (LSB)

0.5

0

01 2 345

(VDC)

V

REF

Voltage

REF

VCC = 5V
V

= 5V

REF

V

= 0V

IN

V

= 3MV

OS

f

= 10.4MHz

CLK

T

= 25 C

A

Figure 4. Unadjusted Offset Error vs V

REF

Voltage

6

ML2258

1.0 FUNCTIONAL DESCRIPTION

1.1 MULTIPLEXER ADDRESSING
The ML2258 contains an 8-channel 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.

SELECTED ADDRESS INPUT

ANALOG CHANNEL ADDR2 ADDR1 ADDR0

IN0 0 0 0
IN1 0 0 1
IN2 0 1 0
IN3 0 1 1
IN4 1 0 0
IN5 1 0 1
IN6 1 1 0
IN7 1 1 1

Table 1. Multiplexer Address Decoding

1.2 A/D CONVERTER
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.

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.

Another advantage of the capacitor array approach used in
the ML2258 over conventional designs 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 75kHz 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 the falling edge initiates a conversion on the
next rising edge of CLK. Four CLK pulses later, sampling of
the analog input begins. The input is then sampled for the
next four CLK periods until EOC goes low. EOC goes low on
the rising edge of the 8th CLK pulse indicating that the
conversion is now beginning. The actual conversion now
takes place for the next 56 CLK pulses, one bit for each 7
CLK pulses. After the conversion is done, the data is updated
on DB0–DB7 and EOC goes high on the rising edge of the
67th CLK pulse, indicating that the conversion has been
completed and data is valid on DB0–DB7. The data will stay

CLK

START

ALE

ADDR0–ADDR2

EOC

DB0–DB7

OE

1/f

CLK

12 4356786667686970

t

SS

t

WS

t

WALE

t

S

t

H

PREVIOUS DATA DATA

t

EOC

t

C

t

EN

t

t

DIS

H

Figure 5. Timing Diagram

7

ML2258

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 ML2258 has a true sample and hold circuit which

samples both the selected input and ground
simultaneously. This simultaneous sampling with a true
S/H will give common mode rejection and AC linearity
performance that is superior to devices where the two
input terminals are not sampled at the same instant and
where true sample and hold capability does not exist.
Thus, the ML2258 can reject AC common mode signals
from DC–50kHz as well as maintain linearity for signals
from DC–50kHz.

The plot below (figure 6) shows a 2048 point FFT of the
ML2258 converting a 50kHz, 0 to 5V, low distortion sine
wave input. The ML2258 samples and digitizes, at its
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 4 CLK periods long and occurs 4 CLK periods 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. 4 CLK periods 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.

The ML2258 has improved latchup immunity. 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.

1.4 REFERENCE
The voltage applied to the +V

REF

and –V

inputs defines

REF

the voltage span of the analog input (the difference
between V

INMAX

and V

) over which the 256 possible

INMIN

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 20ký.

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
+V

pin can be tied to VCC and –V

REF

tied to GND. This

REF

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.

In contrast to the ADC0808 and ADC0809, the ML2258
–V

and +V

REF

symmetric around one half of the supply. +V
–V

can be at any voltage between VCC and GND. In

REF

addition, the difference between +V

reference values do not have to be

REF

and –V

REF

REF

and

REF

can be
set to small values for conversions over smaller voltage
ranges. Particular care must be taken with regard to noise
pickup, circuit layout and system error voltage sources
when operating with a reduced span due to the increased
sensitivity of the converter.

0

–10

–20

–30

–40

–50

–60

–70

MAGNITUDE (dB)

–80

–90

–100

–110

37.5 75

FREQUENCY (kHz)

Figure 6. Output Spectrum

8

ML2258

1.5 POWER SUPPLY AND REFERENCE DECOUPLING
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.

If REF+ and REF– inputs are driven by long lines, they
should be bypassed by 0.1µF Ceramic disc capacitors at
the reference 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 ML2258 is defined as

12



VVVV

+++

22324

THD

=

where V1 is the rms amplitude of the fundamental and V2,
V3, V4, V5 are the rms amplitudes of the individual
harmonics.

20

log



252

V

1

/




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 ML2258 (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 sampling interval starts with the 4th CLK rising edge
after a START falling edge and ends on the 8th rising edge
of CLK, 4 CLK periods later. On the rising edge of the 8th
CLK pulse, the conversion starts and EOC goes low.

Each bit conversion in the successive approximation
process takes 7 CLK periods. On the rising edge of the
64th CLK pulse, the digital output of the conversion is
updated on the outputs DB0–DB7. On the rising edge of
the 65th CLK pulse, EOC goes high indicating the
conversion is done and data on DB0–DB7 is valid.

One feature of the ML2258 over conventional devices 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.

The signal OE drives the data bus, DB0–DB7, into a high
impedance state when held low. This allows the ML2258
to be tied directly to a µP system bus without any latches
or buffers.

9

ML2258

2.0 TYPICAL APPLICATIONS

V

CC

+

–

–15V

15V

DC

DC

600Ω

ANALOG
IN

ML2258

GND

V

CC

V

CC

+

10µF

Figure 7. Protecting the Input from Overvoltage

20kΩ

V

XDR

XDR

1kΩ

ZERO

ADJ

3kΩ

0.15V

CC

IN

–V

ML2258

REF

+V

V

CC

+

10µF

REF

0.85V

CC

Figure 8. Operating with Ratiometric Transducers

15% of VCC - V

- 85% of V

XDR

CC

4kΩ

–

+

1kΩ
FS
ADJ

24kΩ

ML2258

EOC

1/2 74HC221

V

CC

R

START

A

Q

B

CR

C

Figure 9. Continuous Conversion Mode

10

PHYSICAL DIMENSIONS inches (millimeters)

Package: P28N

28-Pin Narrow PDIP

1.355 - 1.365

(34.42 - 34.67)

28

ML2258

0.180 MAX
(4.57 MAX)

0.125 - 0.135
(3.18 - 3.43)

PIN 1 ID

1

0.485 - 0.495

(12.32 - 12.57)

0.450 - 0.456

(11.43 - 11.58)

1

0.045 - 0.055
(1.14 - 1.40)

0.015 - 0.021

(0.38 - 0.53)

Package: Q28

28-Pin PLCC

0.100 BSC
(2.54 BSC)

SEATING PLANE

0.280 - 0.296
(7.11 - 7.52)

0.020 MIN
(0.51 MIN)

0.042 - 0.056
(1.07 - 1.42)

0.299 - 0.325
(7.60 - 8.26)

0.025 - 0.045
(0.63 - 1.14)

(RADIUS)

0º - 15º

0.008 - 0.012
(0.20 - 0.31)

0.042 - 0.048
(1.07 - 1.22)

8

0.050 BSC
(1.27 BSC)

0.026 - 0.032
(0.66 - 0.81)

0.013 - 0.021
(0.33 - 0.53)

PIN 1 ID

15

SEATING PLANE

0.450 - 0.456

22

(11.43 - 11.58)

0.165 - 0.180
(4.06 - 4.57)

0.485 - 0.495

(12.32 - 12.57)

0.148 - 0.156
(3.76 - 3.96)

0.009 - 0.011
(0.23 - 0.28)

0.099 - 0.110
(2.51 - 2.79)

0.300 BSC
(7.62 BSC)

0.390 - 0.430
(9.90 - 10.92)

11

ML2258

ORDERING INFORMATION

ALTERNATE TOTAL TEMPERATURE

PART NUMBER PART NUMBER UNADJUSTED ERROR RANGE PACKAGE

ML2258BIP (EOL) ADC0808CCN ±1/2LSB –40°C to 85°C Molded DIP (P28N)

ML2258BIQ ADC0808CCV –40°C to 85°C Molded PCC (Q28)

ML2258CIP (EOL) ADC0809CCN ±1LSB –40°C to 85°C Molded DIP (P28N)

ML2258CIQ ADC0809CCV –40°C to 85°C Molded PCC (Q28)

© 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.

12

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San Jose, CA 95131

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Fax: [phone]

DS2258-01