LM2480 [NSC]
80V Triple Bias Clamp; 三重80V钳位偏置
| 型号： | LM2480 |
| 厂家： | 
National Semiconductor |
| 描述： | 80V Triple Bias Clamp |
| 文件： | 总4页 (文件大小：88K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
October 2001
LM2480
80V Triple Bias Clamp
General Description
The LM2480 driver is an Integrated 80V triple bias clamp
circuit for DC recovery of each of the AC coupled outputs of
a CRT driver. It is well matched with the DAC outputs of the
LM126X family of pre-amplifiers. Each amplifier has its gain
internally set to -18. The IC is packaged in an industry
standard 8 lead molded DIP package.
n Single supply operation
n Matched to the LM126X family of preamplifiers
Recommended Applications
n CRT monitors requiring DC restoration at the cathodes
Features
n Wide range integrated triple bias clamp
n High input impedance
Block Diagrams
Package Pinout
20008302
FIGURE 2. LM2480 Package Pinout
Order Number LM2480NA
NS Package Number: N08E
20008301
FIGURE 1. Simplified Schematic (One Channel)
© 2001 National Semiconductor Corporation
DS200083
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Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Machine Model
200V
2KV
Human Body Model
Limits of Operating Ranges (Note 3)
Supply Voltage, VCC
+90V
0V to 5V
VCC
70V to 85V
Input Voltage, VIN
VOUT
10V to VCC
0 to 70˚C
Storage Temperature Range, TSTG
Lead Temperature (Soldering,
-65˚C to +150˚C
Ambient Temperature Range, TA
<
10sec.)
300˚C
ESD Tolerance
DC CLAMP ELECTRICAL CHARACTERISTICS TARGETS AND LIMIT
Unless otherwise noted: VCC = +80V, VIN = 2.25VDC, TA = 25˚C.
Symbol Spec Parameter Conditions
Supply Current All channels
Min
Typ
2.1
46
Max
3.5
50
Units
mA
ICC
VOUT
VOUT-Range
VOUTSAT
AV
DC Output Voltage
Output Voltage Range
Max Saturation Limit
DC Voltage Gain
Linearity Error
42
VDC
V
VIN Range = 1.0V - 4.0V
VIN = 4.0V
53
16
VDC
-16
-18
5
-20
LE
See Note 1
%
RIN
Input Resistance
34K
Ω
Note 1: Linearity Error is the variation in DC gain from V = 1.0V to V = 4.0V.
IN
IN
Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.
Note 3: Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications and
the test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may
change when the device is not operated under the listed test conditions.
Note 4: All voltages are measured with respect to GND, unless otherwise specified.
Test Circuit
20008303
FIGURE 3. Test Circuit (One Channel)
>
Figure 3 shows the test circuit for evaluation of the LM2480 Clamp Amplifier. A high impedance VM ( 100MΩ) is used for DC
measurements at the output.
www.national.com
2
Typical Performance Characteristics
(VCC = +80V), Test Circuit - Figure 3 unless otherwise specified.
the supply pin to ground. The electrolytic capacitor should
also be placed reasonably close to the LM2480’s supply and
ground pins.
Application Circuit
The application circuit shown in Figure 5 is designed to help
clamp the voltage at the output of the driver to the desired
level. Capacitor C4 stabilizes the entire node at the anode of
the clamp diode, D3, by creating a low impedance at high
frequencies. Figure 5 also shows the standard application
circuit topology when used with an LM246X CRT driver. It
shows all the components necessary to optimize perfor-
mance as well as to protect against damage from a CRT arc
event. No additional components are required to protect the
LM2480 from arc damage.
20008304
FIGURE 4. Vout vs Vin
THEORY OF OPERATION
The circuit diagram of the LM2480 is shown in Figure 1. The
DC clamp circuit amplifies the input signal by -18 and the
gain is set by the resistor ratio of 18R and R. The output
requires pull-up resistor to 80V. Figure 2 shows the test
circuit used for evaluation of the LM2480 Clamp Amplifier. A
>
high impedance voltmeter ( 100MΩ) is used for DC mea-
surements at the output. The DC transfer function is shown
in Figure 4.
APPLICATION HINTS
20008307
Power Supply Bypass
FIGURE 5. One Channel of the LM2480 and LM246X
Application Circuit
The LM2480 should have proper power supply bypassing for
optimum performance. A 0.1µF capacitor should be con-
nected from the supply pin, Vcc, to ground, as close to the
supply and ground pins as is practical. Additionally, a 1.0µF
electrolycelectrolytictic capacitor should be connected from
Demonstration Hardware
National Semiconductor has designed
a demonstration
neckboard for the LM126X, LM246X, and the LM2480
chipset. To obtain demonstration boards contact the National
Semiconductor Sales Office in your region.
3
www.national.com
Physical Dimensions inches (millimeters)
unless otherwise noted
Molded Dual-In-Line Package (N)
NS Package Number N08E
Note: Information contained in this data sheet is preliminary and may be subject to change without notice.
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COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
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systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
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