Fairchild Semiconductor TMC1103X20 Datasheet

www.fairchildsemi.com

Features

• 8-bit resolution

• 50 Msps conversion rate

• Low power: 100mW per channel @ 20 Msps

• Integral track/hold

• Independent Input Clamps

• Independent clock inputs

• Integral and differential linearity error 0.5 LSB

• Differential phase 0.7 degree

• Differential gain 1.8%

• Single +5V power supply

• Three-state TTL/CMOS-compatible outputs

• Low cost

Applications

• Video digitizing (composite and Y-C)

• VGA and CCD digitizing

• LCD projection panels

• Image scanners

• Personal computer video boards

• Multimedia systems

• Low cost, high speed data conversion

Description

Incorporated into the TMC1103 are three analog-to-digital
(A/D) converters, each with an independent clock, reference
voltage and input clamp. Analog signals are converted to
Triple 8-bit digital words at sample rates up to 50 Msps
(Megasamples per second) per channel.

Integral Track/Hold circuits deliver excellent performance
on signals with full-scale spectral components up to
12 MHz. Innovative two-step conversion architecture and

submicron CMOS technology reduce typical power dissipa­tion to 100 mW per converter.

Power is derived from a single +5 Volt power supply. Out­puts are three-state outputs and TTL/CMOS-compatible.

TMC1103 package is a 80-lead Metric Quad Flat Pack
(MQFP). Performance specifications are guaranteed from
0°C to 70°C.

Block Diagram

8-bit

A/D Converter

R

TA

DA

7-0

OE

A

CLK

A

V

INA

V

CLPA
CLP

A

R

BA

65-1103-01

Clamp

8-bit

A/D Converter

R

TB

DA

7-0

OE

B

CLK

B

V

INB

V

CLPB
CLP

B

R

BB

Clamp

8-bit

A/D Converter

R

TC

DA

7-0

OE

C

CLK

C

V

INC

V

CLPC
CLP

C

R

BC

Clamp

TMC1103

Triple Video A/D Converter with Clamps

8-Bit, 50Msps

Rev. 1.2.0

TMC1103 PRODUCT SPECIFICATION

2

Circuit Function

Within the TMC1103 are three 8-bit A/D converters, each
employing two-step architecture to convert an analog input
to a digital output at rates up to 50 Msps. Input signals are
held in integral track/hold stages during the conversion pro­cess. Operation is pipelined, with one input sample taken and
one output word provided for each CLKX cycle.

Each of the three converters function identically. In the fol­lowing descriptions ‘X’ refers to a generic input/output or
clock where ‘X’ is equivalent to A, B or C.

The first step in the conversion process is a coarse 4-bit
quantization. This determines the range of the subsequent
fine 4-bit quantization step. To eliminate spurious codes, the
fine 4-bit A/D quantizer output is gray-coded and converted
to binary before it is combined with the coarse result to form
a complete 8-bit result.

Analog Input and Voltage References

Each A/D accepts analog signals in the range RBX to RTX into
digital data. Input signals outside this range produce “satu­rated” 00h or FFh output codes. The device will not
be damaged by signals within the range A

GND

to V

DDA

.

Input range is very flexible and extends from the +5 Volt
power supply to ground. Nominal input range is 2 Volts,
extending from 0.6V to 2.6V. Characterization and
performance is specified over this range. However, the
part will function with a full-scale range from 1.0V to 5.0V.
A smaller input range may simplify analog signal condition­ing circuitry, at the expense of additional noise sensitivity
and some reduced differential linearity performance.

External voltage reference sources are connected to the RTX
and RBX pins. RBX can be grounded. Within each A/D con­verter is a reference resistor ladder comprising 255 resistors
that are accessed by the TMC1103 comparators. RTX is con­nected to the top of the ladder, RBX to the bottom. Gain and
offset errors are directly related to the accuracy and stability
of the applied reference voltages.

Input Clamps

A clamp circuit is connected to the input pin V

INX

of each of
the three A/D converters. With CLPX LOW, the input pin is
clamped to the voltage at V

CLPX

. If CLPX is HIGH, the
input pin is high impedance. Clamping adds an offset voltage
to an AC coupled signal to adjust this signal’s amplitude to
the A/D converter input voltage range.

The analog input is corrected through a 0.1mF capacitor to
V

INX

. The source impedance of the analog source should be
less than 50 Ohms. Current pulses through the capacitor over
several clamp cycles until the voltage across the capacitor
equals the difference between V

CLPX

and the voltage at the
analog source during the clamping period. When the switch
is open, the voltage on the coupling capacitor is added to the
analog input, producing a a DC offset input signal.

Input Clamp Circuit

Digital Inputs and Outputs

Sampling of the applied input signal occurs on the falling
edge of the CLKX signal (Figure 1). Output data is delayed
by 2 1/2 CLKX cycles and is valid following the rising edge
of CLKX. Previous output data remains valid for tHO (Out­put Hold Time). New data becomes valid tD (Output Delay
Time) after this rising edge of CLKX.

Whenever the analog input signal is sampled and found to be
at a level beyond the A/D conversion range, the output limits
at 00h or FFh, as appropriate.

Table 1. A/D Output Coding

Note: 1 LSB = (RTX – RBX) / 255

The outputs of the TMC1103 are CMOS- and
TTL-compatible, and are capable of driving four low-power
Schottky TTL loads. An Output Enable control, OEX, places
the A/D outputs in a high-impedance state when HIGH.
The outputs are enabled when OEX is LOW.

Power and Ground

The TMC1103 operates from a single +5 Volt power supply.
For optimum performance, an analog ground plane should
be placed under the TMC1103 the A

GND

and D

GND

pins

should be connected to the system analog ground plane.

Input V oltage Output

RTX + 1 LSB FF

R

TX

FF

RTX - 1 LSB FE

• • • • • •
RBX + 128 LSB 80
RBX + 127 LSB 7F

• • • • • •

RBX + 1 LSB 01

R

BX

00

RBX - 1 LSB 00

A/D Converter

Analog

Input

V

INX

0.1µF

V

CLPX

CLP

X

65-1103-02

PRODUCT SPECIFICATION TMC1103

3

Pin Assignments

NC
DA

5

DA

6

DA

7

OE

A

V

DD

V

DD

NC
CLK

A

NC
V

DDA

V

INA

AGND
R

TA

R

BA

V

CLPA

V

CLPB

V

CLPC

DGND
DGND

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

DGND
DGND
NC
NC
DGND
DGND
V

DD

CLP

A

CLP

B

CLP

C

NC
DGND
DGND
DC

0

DC

1

DC

2

DC

3

DC

4

DC

5

DC

6

21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

Pin Name Pin Name

DC

7

OE

C

V

DD

V

DD

CLK

C

NC
V

DDA

V

INC

AGND
R

TC

R

BC

R

BB

R

TB

AGND
V

INB

V

DDA

NC
CLK

B

NC
V

DD

41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60

V

DD

OE

B

DB

7

DB

6

DB

5

DB

4

DB

3

DB

2

DB

1

DB

0

DGND
DGND
NC
DGND
DGND
DA

0

DA

1

DA

2

DA

3

DA

4

61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80

Pin Name Pin Name

124

65-1103-03

25

40

4164

65

80

PRODUCT SPECIFICATION TMC1103

4

Pin Descriptions

Pin Name Pin Number Value Pin Function Description
A/D Converters

V

INA

, V

INB

,

V

INC

12, 55, 48 RTX to

R

BX

Analog Inputs. The input voltage conversion range lies between the
voltage applied to the RTX and RBX pins.

RTA, RTB, R

TC

14, 53, 50 2.6V Reference Voltage, Top Inputs. DC voltages applied to RTA, RTB

and RTC define highest value of V

INX

.

RBA, RBB, R

BC

15, 52, 51 0.6V Reference Voltage, Bottom Inputs. DC voltages applied to RBA,

RBB and RBC define lowest value of V

INX

.

CLKA, CLKB,
CLK

C

9, 58, 45 CMOS Clock Inputs. CMOS-compatible. V

INX

is sampled on the falling

edge of CLK

X

.

DA

7-0

4, 3, 2, 80, 79,

78, 77, 76

CMOS/

TTL

Data outputs, Converter A (D7 = MSB). Eight-bit CMOS- and
TTL-compatible digital outputs. Valid data is output on the rising
edge of CLKX.

DB

7-0

63, 64, 65, 66,

67, 68, 69, 70

CMOS/

TTL

Data outputs, Converter B (D7 = MSB). Eight-bit CMOS- and
TTL-compatible digital outputs. Valid data is output on the rising
edge of CLKX.

DC

7-0

41, 40, 39, 38,

37, 36, 35, 34

CMOS/

TTL

Data outputs, Converter C (D7 = MSB). Eight-bit CMOS- and
TTL-compatible digital outputs. Valid data is output on the rising
edge of CLKX.

OEA, OEB, OE

C

5, 62, 42 CMOS Output Enable Inputs. CMOS-compatible. When LOW, the A/D

output is enabled. When HIGH, the output is in a high-impedance
state.

Clamps

V

CLPA

, V

CLPB

,

V

CLPB

16, 17, 18 RTX to

R

BX

Clamp Reference Voltage. One reference for each clamp. A V

INX

input is clamped to V

CLPX

when CLPX is low.

CLPA, CLPB,
CLP

C

28, 29, 30 CMOS Clamp Pulse Inputs. One input for each A/D clamp. When CLPX is

low, the V

INX

input is clamped to the V

CLPX

clamp voltage.

Power

V

DDA

11, 47, 56 +5V Analog Supply Voltage. +5 Volt power inputs. These should come

from the same power source and be decoupled to A

GND

.

V

DD

6, 7, 27, 28, 29,

30, 43, 44, 60,

61

+5V Digital Supply Voltage. +5 Volt power inputs. These should come

from the same power source and be decoupled to A

GND

.

A

GND

13, 49, 54 0.0V Analog Ground. Ground connections. These pins should be

connected to the system analog ground plane.

D

GND

16, 17, 18, 19,
20, 21, 22, 25,
26, 32, 33, 71,

72, 74, 75

0.0V Digital Ground. Ground connections. These pins should be
connected to the system analog ground plane.

No Connect

N/C 1, 8, 10, 23, 24,

31, 46, 57, 59,

73

open Not Connected.

PRODUCT SPECIFICATION TMC1103

5

Figure 1. Timing

Equivalent Circuits and Threshold Levels

Figure 2. Equivalent Digital Input Circuit Figure 3. Equivalent Digital Output Circuit

V

INX

Sample N

Sample N+1

Data N-3 Data N-2 Data N-1 Data N

Hi-Z

Sample N+2

Sample N+3

t

STD

t

PWL

t

PWH

t

DIS

t

ENA

t

DO

t

HO

1/f

S

CLK

X

65-1103-04

DX

7-0

OE

X

Digital
Input

V

DD

p

n

27014B

GND

V

DD

p

n

27011B

GND

Digital
Output