LINEAR TECHNOLOGY LTC1099 Technical data

FEATURES

LTC1099

High Speed 8-Bit A/D

Converter with Built-In

Sample-and-Hold

U

DESCRIPTIO

■

Built-In Sample-and-Hold

■

No Missing Codes

■

No User Trims Required

■

All Timing Inputs Edge Sensitive for Easy Processor
Interface

■

Fast Conversion Time: 2.5µs

■

Latched Three-State Outputs

■

Single 5V Operation

■

No External Clock

■

Overflow Output Allows Cascading

■

TC Input Allows User Adjustable Conversion Time

■

0.3" Wide 20-Pin PDIP

U

KEY SPECIFICATIO S

■

Resolution: 8-Bits

■

Conversion Time: 2.5µs (RD Mode)

2.5µs (WR/RD Mode)

■

Slew Rate Limit (Internal S/H): 2.5V/µs

■

Low Power: 75mW Max

■

Total Unadjusted Error

LTC1099: ±1 LSB
LTC1099A: ±0.75 LSB

The LTC®1099 is a high speed microprocessor compatible
8-bit analog-to-digital converter (A/D). An internal sample­and-hold (S/H) allows the A/D to convert inputs up to the
full Nyquist limit. With a conversion rate of 2.5µs, this
allows 156kHz 5V

input signals or slew rates as high as

P-P

2.5V/µs, to be digitized without the need for an external
S/H.

Two modes of operation, Read (RD) mode and Write-Read
(WR-RD) mode, allow easy interface with processors. All
timing is internal and edge sensitive which eliminates the
need for external pulse shaping circuits. The Stand-Alone
(SA) mode is convenient for those applications not involv­ing a processor.

Data outputs are latched with three-state control to allow
easy interface to a processor data bus or I/O port. An
overflow output (OFL) is provided to allow cascading for
higher resolution.

, LTC and LT are registered trademarks of Linear Technology Corporation.

TYPICAL APPLICATION

Infinite Hold Time Sample-and-Hold (T

SAMPLE

HOLD

V

IN V

13

REF

LTC1099

7

MODE

1

IN

6

WR/RDY

8

RD

CS

GND REF

5V

12 20

+

10

V

CC

DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0

10k

14

+

REF

1

17
16
15
14
5
4
3
2

–

11

10k

2
3
4
5
6
7
8

B1
B2
B3
B4
B5
B6
B7
B8

REF

15 17

–

U

15V

V

V

= 240ns) Signal-to-Noise Ratio (SNR) vs Input Frequency

ACQ

–36

20

+

18

I

O

I

O

19

–

2.5k

2

3

7

+

LT1022AM6012

–

–15V

6

V

OUT

4

1099 TA01

–38

–40

–42

–44

–46

–48

SIGNAL-TO-NOISE RATIO, SNR (dB)

–50

–52

1

INPUT FREQUENCY (kHz)

10 100

TA = 25°C

= 2.5µs

T

C

1099 G08

1

LTC1099

V

IN

DB0
DB1
DB2
DB3

WR/RDY

MODE

RD
INT

GND

1
2
3
4
5
6
7
8
9

10

TOP VIEW

SW PACKAGE

20-LEAD PLASTIC SO

20
19
18
17
16
15
14
13
12
11

V

CC

TC
OFL
DB7
DB6
DB5
DB4
CS
REF

+

REF

–

WW

W

ABSOLUTE AXI U RATI GS

U

(Notes 1, 2)

Supply Voltage (VCC) to GND Voltage ...................... 12V

Analog and Reference Inputs... –0.3V to (VCC + 0.3V)

Digital Inputs .........................................– 0.3V to 12V

Digital Outputs ........................ –0.3V to (VCC + 0.3V)

Power Dissipation.............................................. 500mW

UUW

PACKAGE/ORDER I FOR ATIO

TOP VIEW

1

V

IN

2

DB0

3

DB1

4

DB2

5

DB3

6

WR/RDY

7

MODE

8

RD

9

INT

10

GND

T

= 150°C, θJA = 100°C/W

JMAX

N PACKAGE

20-LEAD PDIP

V

20

CC

T

19

C

OFL

18

DB7

17

DB6

16

DB5

15

DB4

14

CS

13

+

REF

12

–

REF

11

Consult factory for parts specified with wider operating temperature ranges.

ORDER PART

NUMBER

LTC1099CN
LTC1099ACN
LTC1099AIN

Operating Temperature Range

LTC1099C/LTC1099AC............................ 0°C to 70°C

LTC1099I/LTC1099AI ..........................–40°C to 85°C

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

Lead Temperature (Soldering, 10 sec)..................300°C

ORDER PART

NUMBER

LTC1099CSW

T

= 150°C, θJA = 130°C/W

JMAX

U

CONVERTER CHARACTERISTICS

temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, REF+ = 5V, REF– = 0V and TA = T
noted.

PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
Accuracy

Total Unadjusted Error (Note 3)

LTC1099A
LTC1099

Minimum Resolution (No Missing Codes) ● 8 8 Bits

Reference Input

Input Resistance ● 1 3.2 6 2 3.2 4.5 kΩ
REF+ Input Voltage Range (Note 4) ● REF
REF– Input Voltage Range (Note 4) ● GND REF

Analog Input

Input Voltage Range ● GND V
Input Leakage Current CS = VCC, VIN = VCC, GND ● ±3 ±3 µA
Input Capacitance 60 60 pF

Sample-and-Hold

Acquisition Time 240 240 ns
Aperture Time 110 110 ns
Tracking Rate 2.5 2.5 V/µs

2

The ● denotes the specifications which apply over the full operating

to T

MIN

LTC1099AI/LTC1099I LTC1099AC/LTC1099C

● ±0.75 ±0.75 LSB

● ±1 ±1 LSB

–

V

CC

+

CC

–

REF

GND REF

GND V

unless otherwise

MAX

V

CC

+

CC

V
V

V

LTC1099

U

DIGITAL AND DC ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VCC = 5V, REF+ = 5V, REF– = 0V and TA = T

SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS

V

IH

V

IL

I

IH

I

IL

V

OH

V

OL

I

OZ

I

SOURCE

I

SINK

I

CC

High Level Input Voltage All Digital Inputs, VCC = 5.25V ● 2.0 2.0 V
Low Level Input Voltage All Digital Inputs, VCC = 4.75V ● 0.8 0.0001 0.8 V
High Level Input Current VIH = 5V; CS, RD, Mode ● 0.0001 1 1 µA

= 5V; WR ● 0.0005 3 0.0005 3 µA

V

IH

Low Level Input Current VIL = 0V; All Digital Inputs ● –0.0001 –1 –0.0001 –1 µA
High Level Output Voltage DB0-DB7, OFL, INT; VCC = 4.75V

I

= 360µA ● 2.4 4.0 2.4 4.0 V

OUT

=10µA 4.7 4.7 V

I

OUT

Low Level Output Voltage DB0-DB7, OFL, INT, RDY; VCC = 4.75V

=1.6mA ● 0.4 0.4 V

I

OUT

Hi-Z Output Leakage DB0-DB7, RDY; V

DB0-DB7, RDY; V
Output Source Current DB0-DB7, OFL, INT; V
Output Sink Current DB0-DB7, OFL, INT, RDY; V
Supply Current CS = WR = RD = V

MIN

to T

unless otherwise noted.

MAX

LTC1099AI/LTC1099I LTC1099AC/LTC1099C

= 5V ● 0.1 3 0.1 3 µA

OUT

= 0V ● –0.1 –3 –0.1 –3 µA

OUT

= 0V ● –11 –6 –11 –7 mA

OUT

= 5V ● 14 7 14 9 mA

OUT

CC

● 11 20 11 15 mA

AC CHARACTERISTICS

otherwise specifications are at TA = 25°C. VCC = 5V, REF+ = 5V, REF– = 0V and TA = T

The ● denotes the specifications which apply over the full operating temperature range,

MIN

to T

unless otherwise noted.

MAX

LTC1099AI/LTC1099I LTC1099AC/LTC1099C

SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
RD Mode (Figure 2) Pin 7 = GND

t

CRD

t

RDY

t

ACC0

t

INTH

t1H, t
t

P

t

ACC2

WR/RD Mode (Figures 3 and 4) Pin 7 = V

t

CWR

t

ACC0

t

ACC2

t

INTH

t

IHWR

t1H, t
t

P

t

WR

Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.

Note 2: All voltages are with respect to GND (Pin 10) unless otherwise

Conversion Time TA = 25°C 2.2 2.5 2.8 2.2 2.5 2.8 µs

● 5.0 3.75 µs

Delay From CS↓ to RDY↓ CL = 100pF 70 70 ns
Delay From RD↓ to Output Data Valid CL = 100pF t

+ 35 t

CRD

+ 35 ns

CRD

Delay From RD↑ to INT↑ CL = 100pF 70 70 ns
Delay From RD↑ to Hi-Z State on Outputs Test Circuit Figure 1 70 70 ns

0H

Delay Time Between Conversions 700 700 ns
Delay Time From RD↓ to Output Data Valid 70 70 ns

CC

Conversion Time TA = 25°C 2.2 2.5 2.8 2.2 2.5 2.8 µs

● 5.0 3.75 µs

Delay Time From WR↓ to Output Data Valid CL = 100pF t

+ 40 t

CWR

+ 40 ns

CWR

Delay From RD↓ to Output Data Valid CL = 100pF 70 70 ns
Delay From RD↑ to INT↑ CL = 100pF 70 70 ns
Delay From WR↓ to INT↑ CL = 100pF 240 240 ns
Delay From RD↑ to Hi-Z State on Outputs Test Circuit Figure 1 70 70 ns

0H

Delay Time Between Conversions 700 700 ns
Minimum WR Pulse Width 55 55 ns

Note 3: Total unadjusted error includes offset, gain, linearity and hold step
errors.

Note 4: Reference input voltage range is guaranteed but is not tested.

noted.

3

LTC1099

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Supply Current vs Temperature

20
18
16

(mA)

14

CC

12
10

8
6

SUPPLY CURRENT, I

4
2
0

–50 – 25 0

AMBIENT TEMPERATURE, TA (°C)

25

50 75 100 125

Total Error vs Reference Voltage

4

3

2

TOTAL ERROR (LSB)

1

1099 G01

TA = 25°C
T

= 2.5µs

C

VOS Error vs Reference Voltage

4

3

2

ERROR (LSB)

OS

V

1

0

0

13

REFERENCE VOLTAGE, V

2

Conversion Time vs R

100

10

1.0

CONVERSION TIME (µs)

RESISTOR BETWEEN
PIN 19 AND V

CC

RESISTOR BETWEEN
PIN 19 AND GND

EXT

TA = 25°C
T

C

(V)

REF

TA = 25°C

= 2.5µs

4

1099 G02

Linearity Error vs Reference
Voltage

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

LINEARITY ERROR (LBS)

0.2

0.1
0

5

0

Accuracy vs Conversion Time

1.0

0.8

0.6

0.4

0.2

TOTAL UNADJUSTED ERROR (LBS)

1

REFERENCE VOLTAGE, V

3

2

TA = 25°C

= 2.5µs

T

C

4

(V)

REF

TA = 25°C

5

1099 G03

4

0

0

REFERENCE VOLTAGE, V

REF

4

(V)

1099 G04

13

2

Conversion Time vs Temperature

1.8

1.6

1.4

1.2

1.0

0.8

CONVERSION TIME/CONVERSION TIME AT 25°C

0.6
–50

–25 0

AMBIENT TEMPERATURE, TA (°C)

25 75

5

50 100 125

0.1
10

1099 G07

RESISTANCE (kΩ)

4.5

4.0

CONVERSION TIME (µs)

3.5

3.0

2.5

2.0

1.5

100 1000

1099 G05

Signal-to-Noise Ratio (SNR) vs
Input Frequency

–36

–38

–40

–42

–44

–46

–48

SIGNAL-TO-NOISE RATIO, SNR (dB)

–50

–52

1

0

1.7 1.9

1.6

1.8

CONVERSION TIME (µs)

INPUT FREQUENCY (kHz)

10 100

2.0

TA = 25°C

= 2.5µs

T

C

1099 G08

2.3

2.1 2.5

2.2

2.4

1099 G06

UUU

PIN FUNCTIONS

LTC1099

VIN (Pin 1): Analog Input.
DB0 to DB3 (Pins 2 to 5): Data Outputs. DB0 = LSB.
WR/RDY (Pin 6): WR/RDY is an input when M0DE = VCC.

Falling edge of WR switches internal S/H to hold then
starts conversion. WR/RDY is an open drain output (active
pull-down) when M0DE = GND. RDY goes low at start of
conversion and pull-down is turned off when conversion
is complete. Resistive pull-up is usually used in this mode.

MODE (Pin 7): WR-RD when MODE = VCC. RD when
M0DE = GND. No internal pull-down.

RD (Pin 8): A Low on RD with CS Low Activates Three­State Outputs. With MODE = GND and CS low, the falling
edge of RD switches internal S/H to hold and starts
conversion.

TEST CIRCUITS

t

1H

tr = 20ns, CL = 10pF

INT (Pin 9): Output that goes low when the conversion in
process is complete and goes high after data is read.

GND (Pin 10): Ground Connection.
REF– (Pin 11): Low Reference Potential (Analog Ground).
REF+ (Pin 12): High Reference Potential. V

= Full Scale

REF

= (REF+) – (REF–).
CS (Pin 13): Chip Select. When high, data outputs are high

impedance and all inputs are ignored.

DB4 to DB7 (Pins 14 to 17): Data Outputs. DB7 = MSB.
OFL (Pin 18): Overflow Output. Goes low when VIN > V

REF

.

TC (Pin 19): User Adjustable Conversion Time.
VCC (Pin 20): Positive Supply. 4.75V ≤ V

≤ 5.25V.

CC

RD

CS

RD

CS

t

r

V

V

CC

DATA
OUT

C

1k

L

t

0H

tr = 20ns, CL = 10pF

V

CC

V

CC

1k

DATA
OUT

C

L

DATA OUT

DATA OUT

RD

RD

GND

V

GND

V

GND

V

V

CC

10%

0H

CC

10%

CC

0L

t

50%

r

90%

50%

t

1H

90%

t

90%

0H

10%

1099 F01

Figure 1. Three-State Test Circuit

5