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AD8387
Service Manual
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Analog Devices AD8387 Service Manual

High Performance, 12-Bit, 12-Channel

FEATURES

High accuracy, high-resolution voltage outputs
1 mV channel matching 12-bit input resolution Laser-trimmed outputs
Fast settling, high voltage drive
35 ns settling time to 0.25% into 150 pF load Slew rate 420 V/μs Outputs to within 1.3 V of supply rails
High update rates
Fast, 110 MHz clock
Programmable video reference (brightness) and
full-scale (contrast) output levels
Flexible logic
INV bit reverses polarity of video signal R/L reverses loading order of data ISW selects frame/row or column/dot inversion DSW selects single or dual data bus mode
Output short-circuit protection
3.3 V logic, 11 V to 18 V analog supplies Available in 80-lead, 12 mm × 12 mm, TQFP E-pad

APPLICATIONS

LCD microdisplay driver

GENERAL DESCRIPTION

The AD8387 DecDriver provides dual, fast latched, 12-bit decimating input, which drives 12 high voltage outputs. Twelve­bit input words are loaded into 12 separate high speed, bipolar DACs sequentially. Flexible digital input format allows more than one AD8387 to be used in parallel for higher resolution displays. The output signal can be adjusted for dc reference, signal inversion, and contrast for maximum flexibility.
The AD8387 is fabricated on ADI’s fast bipolar, 26 V XFCB process, providing fast input logic, bipolar DACs with trimmed accuracy and fast settling, high voltage, precision drive amplifiers on the same chip.
The AD8387 dissipates 1.34 W nominal static power. The AD8387 is offered in an 80-lead TQFP E-pad package and operates over the commercial temperature range of 0°C to +85°C.
Decimating, LCD DecDriver
AD8387

FUNCTIONAL BLOCK DIAGRAM

DBA(0:11)
DBB(0:11)
BYP
TSW
GSW
DSW
CLK XFR
R/L
ΔVDE CHANNEL MATCHING (mV)
12
12 12
BIAS
THERMAL
SWITCH
G-MODE SWITCH
SEQUENCE
CONTROL
5
4
3
2
1
0
CODE 0
CODE 4095
0
10 20 30 40 50 60 70 80
INTERNAL AMBIENT TEMPERATURE (°C)
Figure 2. Channel Matching vs. Temperature
12 12
12
12
TWO-STAGE
LATCH
TWO-STAGE
LATCH
TWO-STAGE
LATCH
TWO-STAGE
LATCH
AD8387
DAC
12
DAC
12
DAC
12
DAC
Figure 1.
NORMAL PROJECTOR OPERATING
TEMPERATURE RANGE
CODE 2048
SCALING
CONTROL
VRLVRHISWINV
VID0
VID1
VID10
VID11
05653-015
®
05653-001
Rev. 0
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 © 2005 Analog Devices, Inc. All rights reserved.
AD8387

TABLE OF CONTENTS

Features .............................................................................................. 1
Theory of Operation ...................................................................... 13
Applications....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 5
Exposed Paddle............................................................................. 5
Overload Protection ..................................................................... 5
Maximum Power Dissipation ..................................................... 5
Operating Temperature Range ................................................... 5
ESD Caution.................................................................................. 5
Pin Configuration and Function Descriptions............................. 6
Typical Performance Characteristics ............................................. 8
Timing Diagrams.............................................................................. 9
Single Data Bus Configuration, DSW = LOW ......................... 9
Transfer Function and Analog Output Voltage...................... 13
Accuracy ...................................................................................... 13
Applications..................................................................................... 14
Optimized Reliability with the Thermal Switch .................... 14
Initial Power-Up After Assembly or Repair............................ 14
Power-Up During Normal Operation ..................................... 14
Power Supply Sequencing ......................................................... 14
Power-On Sequence ................................................................... 14
Power-Off Sequence................................................................... 14
Grounded Output Mode During Power-Off .......................... 14
PCB Design for Optimized Thermal Performance ............... 14
Thermal Pad Design .................................................................. 15
Thermal via Structure Design .................................................. 15
AD8387 PCB Design Recommendations ............................... 15
Outline Dimensions ....................................................................... 16
Dual Data Bus Configuration, DSW = HIGH........................ 10
Functional Description ..................................................................12
Reference and Control Input Description............................... 12

REVISION HISTORY

10/05—Revision 0: Initial Version
Ordering Guide .......................................................................... 16
Rev. 0 | Page 2 of 16
AD8387

SPECIFICATIONS

TA = 25°C, AVCC = 15.5 V, DVCC = 3.3 V, VRH = 9.5 V, VRL = 7 V, T
Table 1.
Parameter Conditions Min Typ Max Unit
VIDEO DC PERFORMANCE
1
T
A MIN
to T
,VFS = 5 V
A MAX
VDE—Differential Error Voltage @ DAC code 0 −5.5 −0.8 +5.0 mV @ DAC code 1024 −4.4 −0.5 +3.6 mV @ DAC code 2048 −3.6 −0.3 +3.3 mV @ DAC code 3072 −2.8 −0.3 +2.8 mV @ DAC code 4095 −2.1 +0.2 +2.1 mV DAC code range 0 to 4095 −6.0 +6.0 mV
VCME—Common-Mode Error Voltage @ DAC code 0 −2.5 −0.3 +2.5 mV @ DAC code 1024 −2.5 −0.3 +2.5 mV @ DAC code 2048 −2.5 −0.3 +2.5 mV @ DAC code 3072 −2.5 −0.3 +2.5 mV @ DAC code 4095 −2.5 −0.3 +2.5 mV DAC code range 0 to 4095 −3.5 +3.5 mV
ΔVDE—VDE Channel Matching @ DAC code 0 1.9 4.8 mV @ DAC code 1024 1.8 4.3 mV @ DAC code 2048 1.6 4.0 mV @ DAC code 3072 1.4 3.8 mV @ DAC code 4095 1.0 2.8 mV DAC code range 0 to 4095 5.5 mV
ΔV—Channel Matching @ DAC code 0 2.7 mV @ DAC code 1024 2.7 mV @ DAC code 2048 2.5 mV @ DAC code 3072 2.5 mV @ DAC code 4095 2.0 mV DAC code range 0 to 4095 7.5 mV
2
DNL
VIDEO OUTPUT DYNAMIC PERFORMANCE T
−1 −0.2 LSB to T
A MIN
A MAX
Data Switching Settling Time to 0.25% VIDx = 5 V step, CL = 150 pF 35 50 ns Data Switching Settling Time to 1% 22 28 ns Data Switching Slew Rate 20% to 80% 420 V/μs CLK and Data Feedthrough All-Hostile Crosstalk
3
4
15 mV p-p
Amplitude 69 mV p-p Glitch Duration 50 ns DAC Transition Glitch Energy DAC Code 2047 to 2048 0.4 nV-s
Invert Switching Settling Time to 0.25% VIDx = 10 V step, CL = 150 pF 70 150 ns Invert Switching Settling Time to 1% 34 40 ns Invert Switching Slew Rate 20% to 80% 700 V/μs Invert Switching Overshoot 25 mV
Rev. 0 | Page 3 of 16
A MIN
= 0°C, T
= 75°C still air, unless otherwise noted.
A MAX
AD8387
Parameter Conditions Min Typ Max Unit
VIDEO OUTPUT CHARACTERISTICS
Output Voltage Swing AVCC − VOH, VOL − AGND 0.9 1.3 V Output Voltage—Grounded Mode 0.06 0.150 V Data Switching Delay: t Data Switching Delay Skew: Δt INV Switching Delay: t INV Switching Delay Skew: Δt Output Current 100 mA Output Resistance 28 Ω
REFERENCE INPUTS
VRL Range VRH ≥ VRL 5.25 AVCC − 4 V VRH Range VRH ≥ VRL VRL VRL + 2.75 V VRH to VRL Range VRH Input Resistance To VRL 22 kΩ VRL Input Current −44 μA
VRH Input Current 111 μA RESOLUTION Binary Coding 12 Bits DIGITAL INPUT CHARACTERISTICS
CLK Frequency DSW = HIGH 110 MHz
DSW = LOW 85 MHz
Data Setup Time: t1 0 ns
XFR Setup Time: t3 0 ns
Data Hold Time: t2 3.5 ns
XFR Hold Time: t4 3.5 ns
CLK High Time: t5 DSW = HIGH 2.5 ns
CLK Low Time: t6 DSW = HIGH 3.0 ns
CLK High Time: t7 DSW = LOW 3.5 ns
CLK Low Time: t8 DSW = LOW 4.0 ns
CIN 3 pF
IIH 0.05 μA
IIH TSW 333 μA
IIH XFR 0.05 μA
IIL −0.6 μA
IIL TSW −1.3 μA
IIL XFR −1.2 μA
VIH 2 V
VIL 0.8 V
VTH 1.65 V POWER SUPPLIES
DVCC, Operating Range 3 3.3 3.6 V
DVCC, Quiescent Current 54 70 mA
AVCC, Operating Range 11 18 V
AVCC, Quiescent Current 75 100 mA OPERATING TEMPERATURE
Ambient Temperature Range, T
Ambient Temperature Range, T
1
VDE = differential error voltage, VCME = common-mode error voltage, ΔVDE = VDE matching between outputs, ΔV = maximum deviation between outputs, and full-scale output
voltage = VFS = 2 × (VRH − VRL). See the Accuracy section.
2
Guaranteed monotonic by characterization to four sigma limits.
3
Measured on two outputs differentially as CLK and DBx(0:11) are driven and XFR is held LOW.
4
Measured on two outputs differentially as the others are transitioning by 5 V. Measured for both states of INV.
5
Measured from 50% of rising CLK edge to 50% of output change. Measurement is made for both states of INV.
6
Measured from 50% of INV transition to 50% of output change.
7
Operation at elevated ambient temperature requires a thermally optimized PCB and additional thermal management, such as airflow across the surface of the AD8387.
5
7
6
8
1
5
7
6
8
VIDx = 5 V step 15.7 ns 4 ns VIDx = 10 V step 16.2 ns 4 ns
0 2.75 V
T
A MIN
to T
A MAX
CLK input duty cycle 40% to 60%
7
A
7
A
Still air, TSW = LOW 0 75 °C 200 lfm airflow, TSW = LOW 0 85 °C
Rev. 0 | Page 4 of 16
AD8387

ABSOLUTE MAXIMUM RATINGS

Table 2.
Parameter Rating
Supply Voltages
AVCCx − AGNDx 18 V DVCC − DGND 4.5 V
Input Voltages
Maximum Digital Input Voltage DVCC + 0.5 V Minimum Digital Input Voltage DGND − 0.5 V Maximum Analog Input Voltage AVCC + 0.5 V Minimum Analog Input Voltage AGND − 0.5 V
Internal Power Dissipation
1
TQFP E-Pad @ TA = 25°C 4.38 W Operating Temperature Range 0°C to 85°C Storage Temperature Range −65°C to +125°C Lead Temperature Range (Soldering 10 sec) 300°C
1
80-lead TQFP E-Pad:
θJA = 28.5°C/W (still air) [JEDEC Standard, 4-layer PCB in still air]
θJC = 12.2°C/W
θJB = 14.6°C/W
ΨJB = 12.0°C/W
ΨJT = 0.3°C/W.
Stresses above those listed under the Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to the absolute maximum ratings for extended periods may reduce device reliability.

EXPOSED PADDLE

To ensure optimized thermal performance, the exposed paddle must be thermally connected to an external plane, such as AVCC or GND, as described in the
Applications section.

OVERLOAD PROTECTION

The AD8387 overload protection circuit consists of an output current limiter and a thermal switch.
When TSW is LOW, the thermal switch is disabled and the output current limiter is enabled. The maximum current at any one output is internally limited to 100 mA average. In the event of a momentary short-circuit between a video output and a power supply rail (VCC or AGND), the output current limit is sufficiently low to provide temporary protection.
When TSW is HIGH, the output current limiter, as well as the thermal switch, is enabled. The thermal switch debiases the output amplifier when the junction temperature reaches the internally set trip point. In the event of an extended short­circuit between a video output and a power supply rail, the output amplifier current continues to switch between 0 and 100 mA typical with a period determined by the thermal time constant and the hysteresis of the thermal trip point. The thermal switch, when enabled, provides long-term protection from accidental shorts during the assembly process by limiting the average junction temperature to a safe level.

MAXIMUM POWER DISSIPATION

The maximum power that the AD8387 can safely dissipate is limited by its junction temperature. The maximum safe junction temperature for plastic encapsulated devices, as determined by the glass transition temperature of the plastic, is approximately 150°C. Exceeding this limit temporarily can cause a shift in the parametric performance due to a change in the stresses exerted on the die by the package. Exceeding a junction temperature of 150°C for an extended period can result in device failure.

OPERATING TEMPERATURE RANGE

To ensure operation within the specified operating temperature range, it is necessary to limit the maximum power dissipation as follows.
3.0
200LFM
2.5
STILL AIR
2.0
1.5 QUIESCENT
MAXIMUM POWER DISSIPATION (W)
THERMAL
SWITCH ENABLED DISABLED
AD8387 on a 4-Layer JEDEC PCB with Thermally Optimized Landing
1.0 50 55 60 65 70 75 80 85 90 10095
75 80 85 90 95 100 105 110 115 125120
Figure 3. Maximum Power Dissipation vs. Temperature,
Pattern as Described in the
500LFM
AMBIENT TEMPERATURE (°C)
Applications Section
05653-002

ESD CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
Rev. 0 | Page 5 of 16
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