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MAX445のメーカーはMaxim Integratedです、この部品の機能は「200MHz Video CRT Driver」です。 |
部品番号 | MAX445 |
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部品説明 | 200MHz Video CRT Driver | ||
メーカ | Maxim Integrated | ||
ロゴ | |||
このページの下部にプレビューとMAX445ダウンロード(pdfファイル)リンクがあります。 Total 8 pages
19-0302; Rev 0; 9/94
Low-Cost, High-Resolution, 200MHz
Video CRT Driver
_______________General Description
The MAX445 is a high-performance, monolithic, variable-
gain transconductance amplifier with a high-voltage
open-collector output capable of directly driving a video
display (CRT cathode). A 2.5ns rise time is achieved
using a peaking network with a 200Ω load resistor and
an 8pF total load (CRT and parasitic capacitance).
Differential inputs and a linear adjustable gain stage
with an output offset adjustment make the versatile
MAX445 well suited for many video display applica-
tions. A buffered bandgap reference voltage is avail-
able for the gain (contrast) and offset adjustments
along with a TTL BLANK input to turn off the output cur-
rent, independent of signal input.
The MAX445 is available in a 24-pin power-tab DIP
package. A suitable heatsink must be attached to
maintain the junction temperature within the recom-
mended operating range.
________________________Applications
CRT Driver for High-Resolution Monochrome and
Color Displays
High-Voltage, Variable-Gain Transconductance
Amplifier
____________________________Features
o 2.5ns Rise/Fall Time into an 8pF Load
o 200MHz Small-Signal Bandwidth
o 50Vp-p Output
o Ground Referenced Differential Inputs
o Linear Variable Gain for Contrast Control
o Offset Adjustment for Black Level
o 5.5V Bandgap Reference
o Drives 1280 x 1024 and 1530 x 1280 Displays
______________Ordering Information
PART
MAX445CPG
MAX445C/D
TEMP. RANGE
0°C to +70°C*
0°C to +70°C**
PIN-PACKAGE
24 Power-Tab DIP
Dice
* Case temperature range, TCASE = 0°C to +90°C. See Absolute
Maximum Ratings and Applications Information for thermal/heat
sink considerations.
**Dice are specified at TJ = +25°C, DC parameters only.
________________Functional Diagram
CONTRAST
BLANK
VAA
RL
VOUT
IOUT
VIN+
VIN-
GNDA
MAX445
PRE-AMP
CURRENT
AMP
BAND
GAP
VCB
OFFSET
VREF
GND
__________________Pin Configuration
TOP VIEW
GND
VREF
OFFSET
CONTRAST
GNDA
VIN-
VIN+
VEE
VEE
VCC
BLANK
GND
1
2
3
4
5
6
7
8
9
10
11
12
MAX445
24 GND
23 GND
22 GND
21 VEEO
20 N.C.
19 IOUT
18 N.C.
17 VCB
16 VCB
15 GND
14 GND
13 GND
Power-Tab DIP
________________________________________________________________ Maxim Integrated Products 1
Call toll free 1-800-998-8800 for free samples or literature.
http://www.Datasheet4U.com
1 Page Low-Cost, High-Resolution, 200MHz
Video CRT Driver
ELECTRICAL CHARACTERISTICS (continued)
(VAA = 20V, VCB = 10V ±0.5V, VCC = 10V ±0.5V, VEE = -10.5V ±0.5V, VIN = (VIN+) - (VIN-) = 0V, CONTRAST = 1.0V,
OFFSET = 1.0V, RL = 0Ω, BLANK = 0.4V, TCASE = +25°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX UNITS
Rise/Fall Time (10% to 90%)
Settling Time (90% to 100% ±2%)
Thermal Distortion
RL = 200Ω,
No peaking,
tr, tf
CL = 8pF,
VAA = 75V,
OUTp-p = 50V
With peaking,
tr(VIN) < 1ns,
OUTp-p = 45V
ts CL = 8pF, no peaking
3.6
ns
2.5
8 ns
±2 %
______________________________________________________________Pin Description
PIN
1, 12, 13, 14,
15, 22, 23, 24
2
3
4
5
6
7
8, 9
10
11
16, 17
18, 20
19
21
NAME
GND
VREF
OFFSET
CONTRAST
GNDA
VIN-
VIN+
VEE
VCC
BLANK
VCB
N.C.
IOUT
VEEO
FUNCTION
High-Current Ground. Connect all pins to ground plane.
Reference Output (+5.5V)
Output Voltage Offset-Adjustment Input
Output Gain-Adjustment Input
Pre-Amp Ground
Inverting Signal Input
Noninverting Signal Input
Negative Supply (-10.5V)
Positive Supply (+10V)
Blanking Input, TTL
Output Common-Base Supply (+10V)
No Connection—leave open
Open-Collector Current Output
Negative Supply for Output Stage (-10.5V)
_______________________________________________________________________________________ 3
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3Pages Low-Cost, High-Resolution, 200MHz
Video CRT Driver
Table 1. Peaking Networks
(RL = 200Ω, RS = 100Ω)
CL (pF) L3 (nH) L1 (nH) L2 (nH) CB (pF) tR (ns)
2 0 20 60 0.4 1.7
4 0 40 120 0.8 1.9
6 20 60 180 1.1 2.1
8 50 80 240 1.5 2.3
10 75 100 300 2.0 2.7
12 100 120 360 2.2 3.0
Inductors L1, L2, and L3 should be air or ferrite-core
coils with self-resonant frequencies higher than
500MHz.
Thermal Environment
The MAX445 can dissipate a large amount of power
depending on speed and load-driving requirements. The
power-tab package provides a low thermal resistance
path from the chip to an external heatsink. Be sure the
board design provides sufficient heatsinking capacity for
the intended operating range. When mounting to a chas-
sis, it should be noted that the device tab is attached to
VEE (-10.5V). This tab should be electrically isolated from
ground through a thermally conductive insulator.
It is highly recommended that the external heatsink be
connected to ground, since an arc or electrostatic dis-
charge entering the heatsink may break down or
bypass the tab insulator and damage the device. Also,
the grounded heatsink to package tab capacitance will
help to bypass the VEE supply. Another option would
be to bypass the heatsink to ground with a 0.01µF
capacitor with no tab insulator. Inadvertently shorting
the package tab to ground for less than 10 seconds will
not cause component damage. Junction-to-case ther-
mal resistance is rated at 6°C/W for the power-tab DIP
package. Table 2 shows the relationship of output volt-
age and duty cycle to total power.
Table 2. Power Dissipation at VAA = 70V
and Load Resistor = 200Ω
Output Level
Relative to
Black (V)
Duty Cycle
(%)
IC Power
(W)
Load Power
(W)
Total
(W)
0 0 1.6 0 1.6
35
100 7.8
6.1 13.9
35 80 6.5 4.9 11.4
50 80 5.6 10.0 15.6
Circuit Layout and Bypassing
Due to the extremely high-speed performance of the
MAX445, layout design precautions are required to
realize the display driver’s full high-speed capability.
The precautions are as follows:
1) A printed circuit board with a good, unbroken, low-
inductance ground plane is required.
2) Place a decoupling capacitor (0.01µF ceramic) as
close to VCC as possible.
3) Pay close attention to the decoupling capacitors’
resonant frequency and keep leads short.
4) On the inputs and outputs, keep lead lengths short
to avoid unwanted parasitic feedback around the
display driver.
5) Solder the MAX445 directly to the printed circuit
board. Do not use sockets.
200 3.0
175 2.5
150 2.0
125 1.5
100
2
4 6 8 10
LOAD CAPACITANCE (pF)
12
1.0
2
4 6 8 10
LOAD CAPACITANCE (pF)
Figure 2. Typical Rise/Fall Time vs. Loading, with Peaking Network Optimized for Load Capacitance
12
6 _______________________________________________________________________________________
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6 Page | |||
ページ | 合計 : 8 ページ | ||
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PDF ダウンロード | [ MAX445 データシート.PDF ] |
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