SPT SPT5140SIN Datasheet

SPT

SIGNAL PROCESSING TECHNOLOGIES

SPT5140

8-BIT, ULTRAHIGH-SPEED D/A CONVERTER

FEATURES

• 400 MWPS nominal conversion rate

• RS-343-A compatible

• Complete video controls: Sync, Blank, Bright and Reference White (Force High)

• 10 KH, 100K ECL compatible

• Single power supply

• Registered data and video controls

• Differential current outputs

• Stable on-chip bandgap reference

• 50 and 75 ohm output drive

• ESD-protected data and control inputs

GENERAL DESCRIPTION

The SPT5140 is a monolithic 8-bit digital-to-analog converter capable of accepting video data at 400 MWPS. Complete with video controls — Sync, Blank, Reference White (Force High), Bright — the SPT5140 directly drives doubly-terminated 50 or 75 ohm loads to standard composite video levels. Standard set-up level is 7.5 IRE. The

BLOCK DIAGRAM

APPLICATIONS

• Raster graphics

• High-resolution color or monochrome displays to 2k x 2k pixels

• Medical electronics: CAT, PET, MR imaging displays

• CAD/CAE workstations

• Solids modeling

• General-purpose high-speed D/A conversion

• Digital synthesizers

• Automated test equipment

• Digital transmitters/modulators

SPT5140 includes an internal precision bandgap reference which can drive two other SPT5140s in an RGB graphics system.

The SPT5140 is available in a 24-lead PDIP package in the industrial temperature range of –25 °C to +85 °C. Contact the factory for military temperature and /883 versions.

Video Controls In

Video Data In

Feedthrough

Convert

Set

Ref In

Ref Out

Sync, Blank, Bright, Ref – White

D0–D3

4 to 15

D4–D7

(MSBs)

Decode

Ref

Buffer

Bandgap

Reference

Out +

Output

Current

Switches

Out –

Signal Processing Technologies, Inc.

4755 Forge Road, Colorado Springs, Colorado 80907, USA

Phone: (719) 528-2300 FAX: (719) 528-2370 Website: http://www.spt.com E-Mail: sales@spt.com

ABSOLUTE MAXIMUM RATINGS (Beyond which damage may occur)1 25 °C

Supply Voltages

VEE (measured to VCC) .......................... –7.0 to 0.5 V

Temperature

Operating,ambient............................... –25 to +85 °C

junction ....................................... + 175 °C

Input Voltages

CONV, Data, and Controls...................... VEE to 0.5 V

Lead, soldering (10 seconds) ...................... + 300 °C

Storage ............................................. –60 to + 150 °C

(measured to VCC)

Ref+ (measured to VCC) ......................... VEE to 0.5 V

Ref– (measured to VCC).......................... VEE to 0.5 V

Note 1: Operation at any Absolute Maximum Rating is not implied. See Electrical Specifications for proper nominal applied

conditions in typical applications.

ELECTRICAL SPECIFICATIONS

VCC = ground, VEE = –5.2 V ±0.3 V, TA = T

PARAMETERS CONDITIONS LEVEL MIN TYP MAX UNITS DC Electrical Characteristics

Integral Linearity Error 1.0 mA<I

Differential Linearity Error 1.0 mA<I

Gain Error VI –6.5 +6.5 % FS Gain Error Tempco V 150 PPM/°C Bandgap Tempco V 100 PPM/°C Input Capacitance, I Compliance Voltage, + Output VI –1.2 1.5 V Compliance Voltage, – Output VI –1.2 1.5 V Equivalent Output Resistance VI 20 kΩ Output Capacitance V 9 pF Maximum Current, + Output IV 45 mA Maximum Current, – Output IV 45 mA Output Offset Current VI 0.05 0.5 LSB Input Voltage, Logic High VI –1.0 V Input Voltage, Logic Low VI –1.5 V Convert Voltage, IV –0.5 –2.5 V

Common Mode Range (V Convert Voltage, Differential (V Input Current, Logic Low, VI 35 120 µA

Data and Controls Input Current, Logic High, VI 40 120 µA

Data and Controls Input Current, Convert VI 2 60 µA Reference Voltage

Measured to V Reference Output Current VI –50 µA Input Capacitance, V 3 pF

Data and Controls Power Supply Sensitivity VI –120 +20 +120 µA/V Supply Current VI 155 220 mA

, Ref Out V 5 pF

Set

)

ICM

) IV 0.4 1.2 V

IDF

to T

MIN

TEST TEST SPT5140

, CC = 0 pF, I

MAX

<1.3 mA VI –0.37 +0.37 % FS

Set

<1.3 mA VI –0.2 +0.2 % FS

Set

= 1.105 mA, unless otherwise specified.

Set

–0.95 +0.95 LSB

–0.5 +0.5 LSB

VI –1.3 –1.2 –1.0 V

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ELECTRICAL SPECIFICATIONS

VCC = ground, VEE = –5.2 V ±0.3 V, TA = T

PARAMETERS CONDITIONS LEVEL MIN TYP MAX UNITS Dynamic Characteristics (RL = 37.5 ohms, CL = 5 pF, TA = +25 °C, I

Maximum Conversion Rate IV 385 400 MWPS Rise Time 10% to 90% G.S. IV 900 ps Rise Time 10% to 90% G.S. IV 600 ps

Current Settling Time, Clocked To 0.2% G.S. V 4 ns

Mode (t

)

Current Settling Time, Clocked To 0.2% G.S. V 3 ns

Mode (t

Clock to Output Delay, Clocked IV 2.2 4 ns

Mode (t

) T

DSC

Part-to-Part Clock to Output Delay

Skew, Clocked Mode T Data to Output Delay, IV 3.2 6 ns

Transparent Mode (t

) T

DST

Glitch Energy Area = 1/2 VT V 4 pV-s Convert Pulse Width (t

PWH

, t

) IV 1.3 ns

PWL

Reference Bandwidth, –3 dB V 1.25 MHz Set-up Time, Data and Controls (tS) IV 1.0 ns Hold Time, Data and Controls (tH) IV 0.5 ns Slew Rate 20% to 80% G.S. V 700 V/µS Clock Feedthrough IV –48 dB

MIN

to T

, CC = 0 pF, I

MAX

Set

TEST TEST

Set

RL = 25 ohms

= 25 Ω

= T

MIN

to T

MAX

IV 4.5 ns

IV 1.5 ns

IV 6 ns

= 1.105 mA, unless otherwise specified.

= 1.105 mA)

TEST LEVEL CODES

All electrical characteristics are subject to the following conditions:

All parameters having min/max specifications are guaranteed. The Test Level column indicates the specific device testing actually performed during production and Quality Assurance inspection. Any blank section in the data column indicates that the specification is not tested at the specified condition.

TEST LEVEL TEST PROCEDURE

I 100% production tested at the specified temperature.

II 100% production tested at TA = +25 °C, and sample tested at the

specified temperatures. III QA sample tested only at the specified temperatures. IV Parameter is guaranteed (but not tested) by design and characteriza-

tion data.

V Parameter is a typical value for information purposes only.

VI 100% production tested at T

specified temperature range.

= +25 °C. Parameter is guaranteed over

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Figure 1 – Functional Diagram

D0–D7

Composite

Video Controls

CONV CONV

Feedthrough

Decoding

Logic

APPLICATION INFORMATION

The SPT5140 is a high-speed video digital-to-analog converter capable of up to 400 MWPS conversion rates. This makes the devices suitable for driving 2048 X 2048 pixel displays at update rates of 60 to 90 Hz.

In addition, the SPT5140 includes an internal bandgap reference which may be used to drive two other SPT5140s if desired.

The SPT5140 has 10KH and 100K ECL logic level compatible video control and data inputs. The complementary analog output currents produced by the devices are proportional to the product of the digital control and data inputs in conjunction with the analog reference current. The SPT5140 is segmented so that the four MSBs of the input data are separated into a parallel “thermometer” code. From here, fifteen current sinks, which are identical, are driven to fabricate sixteen coarse output levels. The remaining four LSBs drive four binary weighted current switches.

MSB currents are then summed with the LSBs that provide a one-sixteenth of full-scale contribution to provide the 256 distinct analog output levels.

The video control inputs drive weighted current sinks which are added to the output current to produce composite video output levels. These controls — Sync, Blank, Reference White (Force High) and Bright — are needed in video applications.

Another feature that similar video D/A converters do not have is the Feedthrough Control. This pin allows registered or unregistered operation of the video control and

Data

Registers

Bandgap

Reference

Ref Out

Current

Sources

and

Switches

Current

Source

Biasing

Amp

+–

Ref In

Set

Out + Out –

data inputs. In the registered mode, the composite functions are latched to the pixel data to prevent screen-edge distortions generally found on unregistered video DACs.

TYPICAL INTERFACE CIRCUIT

GENERAL

A typical interface circuit using the SPT5140 in a color raster application is shown in figure 2. The SPT5140 requires few external components and is extremely easy to use. The very high operating speeds of the SPT5140 require good circuit layout, decoupling of supplies, and proper design of transmission lines. The following considerations should be noted to achieve best performance.

INPUT CONSIDERATIONS

Video input data and controls may be directly connected to the SPT5140. Note that all ECL inputs are terminated as closely to the device as possible to reduce ringing, crosstalk and reflections. A convenient and commonly used microstrip impedance is about 130 ohms, which is easily terminated using a 330 ohm resistor to VEE and a 220 ohm resistor to ground. This arrangement gives a Thevenin equivalent termination of 130 ohms to –2 volts without the need for a –2 volt supply. Standard SIP (Single Inline Package) 220/330 resistor networks are available for this purpose.

It is recommended that stripline or microstrip techniques be used for all ECL interface. Printed circuit wiring of known impedance over a solid ground plane is recommended.

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