NSC LM1290

LM1290
Autosync Horizontal Deflection Processor
General Description
Features
The LM1290 is a high-performance, low-cost deflection solution for autosync monitors.
n Full autosync — 22 kHz to 110 kHz with no component
switching or external adjustments
n No manufacturing trims needed — internal VCO
capacitor trimmed on chip
n Sample-and-hold circuit for fast top-of-screen phase
recovery, even when using composite sync
n DC-controlled H phase and duty cycle
n Resistor-programmable minimum VCO frequency
n Excellent jitter performance
n X-ray input disables H drive until VCC powered down
n Low VCC disables H drive (VCC < 8.5V)
n H output transistor protected against accidental turn on
during flyback
n Capacitor-programmable frequency ramping, dfVCO / dt,
protects H output transistor during scanning mode
changes
The LM1290 provides full autosync capability, DC controls
and complete freedom from manufacturing trims. Its continuous capture range is from 22 kHz to 110 kHz (1:5). Mode
change frequency ramping, for protection of the horizontal
deflection output transistor, is programmable by using an external capacitor.
Together with the National Semiconductor LM1296 Raster
Geometry Correction System for Multi-Frequency Displays,
excellent performance is offered. The two-chip solution provides the advantage of good jitter performance, simplified
board layout, and lower system cost.
The LM1290 is packaged in a 14-pin plastic DIP package.
Connection Diagram
DS012917-1
FIGURE 1.
Order Number LM1290N
See NS Package Number N14A
© 1999 National Semiconductor Corporation
DS012917
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LM1290 Autosync Horizontal Deflection Processor
January 1997
Absolute Maximum Ratings (Notes 1, 3)
Thermal Resistance (θJA)
Junction Temperature (TJ)
ESD Susceptibility (Note 5)
Storage Temperature
Lead Temperature
(Soldering 10 seconds)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (VCC)
Input Voltage (VDC)
Pin 1
Pins 3, 4, 5, 6
Pin 10
Pin 12
Output Sink Current, Pin 7
Power Dissipation (PD)
(Above 25˚C, derate based on θJA
and TJ)
15V
8V
VCC
1.0V < VDC < 7.5V
10V
130 mA
75˚C/W
150˚C
3.5 kV
−65˚C to +150˚C
265˚C
Operating Ratings (Note 2)
Operating Temperature Range
Supply Voltage
−20˚C to +80˚C
10.8V ≤ VCC ≤ 13.2V
1.65W
Electrical Characteristics
See Test Circuit (Figure 2) ; TA = 25˚C; VCC = 12V; V5 = 0V unless otherwise stated.
Parameter
Condition
Typical
Limit
(Note 6)
(Note 7)
Units
30
40
mA (max)
Supply Current (Pin 14)
Pin 3 and Pin 7 Open Circuit,
Pin 1 = −100 µA
Minimum Capture Frequency
H Sync Duty Cycle = 10%;
10
22
kHz (max)
Maximum Capture Frequency
Pin 1 (fMIN) Open
115
110
kHz (min)
H/HV SYNC Input (Pin 3)
High Level
2.2
V (min)
Threshold Voltage
Low Level
0.8
V (max)
24
%
H/HV SYNC Input (Pin 3)
26
Maximum Sync Tip Duty Cycle
H/HV SYNC Input (Pin 3)
fH = 22 kHz
%
5
Minimum Sync Tip Duty Cycle
H/HV POLARITY (Pin 2)
CPOL = 0.1 µF; IOL = +1 µA
0.05
0.4
V (max)
CPOL = 0.1 µF; IOL = −1 µA
4.5
4
V (min)
Low Level Output Voltage, VOL
H/HV POLARITY (Pin 2)
High Level Output Voltage, VOH
FVC Gain
22 kHz ≤ f
0.055
V/kHz
VCO Gain
22 kHz ≤ fVCO ≤ 110 kHz
H Sync Duty Cycle = 10%:
18.2
kHz/V
fH = 110 kHz
fH = 60 kHz
fH = 22 kHz
120
Phase Detector 1 Gain
H
≤ 110 kHz
µA/radian
80
30
Phase Detector 1 Output Impedance
20
kΩ
(Pin 12)
Phase Detector 1 Leakage Current +
H/HV SYNC Input Grounded
0.3
2
µA
VCO Bias Current (Pin 12)
Jitter
Free Run Frequency Variation
H Drive Phase Control Gain
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fH = 110 kHz (Note 8)
fH = 90 kHz
fH = 60 kHz
fH = 31 kHz
fH = 22 kHz
I1 = −225 µA
0.9
1.1
1.6
ns p-p
3.6
5.8
V10 = 2V to 6V (Note 11)
2
32
34
kHz (max)
26
25
kHz (min)
8.89
% TH/V
(32)
(˚/V)
Electrical Characteristics
(Continued)
See Test Circuit (Figure 2) ; TA = 25˚C; VCC = 12V; V5 = 0V unless otherwise stated.
Parameter
Condition
Typical
Limit
(Note 6)
(Note 7)
H Drive Phase Control Range
V10 = 3.6V to 7V (Notes 9, 11)
± 14
H Drive Duty Cycle Control Gain
(See Application Hint #3)
V4 = 0V to 4V (Note 10)
V4 = 0V (Note 10)
10.8
H Drive Duty Cycle Maximum (Pin 7)
Units
%TH
%/V
68
63
% (min)
25
35
% (max)
H Drive Low Level Output Voltage (Pin 7)
V4 = 4V (Note 10)
IOL = 100 mA
0.7
V
Flyback Input Threshold Voltage (Pin 6)
Positive-Going Flyback Pulse
2.2
V
Maximum Allowable Storage Delay of
From H Drive Rising Edge to
Horizontal Deflection Output Transistor
Center of Flyback Pulse
30
%TH
H Drive Duty Cycle Minimum (Pin 7)
Plus Half of Flyback Pulse Width
VCC Lockout Threshold Voltage
VCC Below Threshold:
(Pin 14)
H Drive Output Disabled
VCC Above Threshold:
8.5
V (max)
10.5
V (min)
2
V (min)
H Drive Output Enabled
X-Ray Shutdown Threshold Voltage
Above Threshold:
(Pin 5)
H Drive Output Disabled
1.85
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.
Note 2: Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications and
test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test conditions.
Note 3: All voltages are measured with respect to GND, unless otherwise specified.
Note 4: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA and the ambient temperature, TA. The maximum
allowable power dissipation at any elevated temperature is PD = (TJMAX − TA)/θJA or the number given in the Absolute Maximum Ratings, whichever is lower. For
this device, TJMAX = 150˚C. The typical thermal resistance (θJA) of the LM1290N is 75˚C/W.
Note 5: Human Body model, 100 pF capacitor discharged through a 1.5 kΩ resistor.
Note 6: Typical specifications are at TA = 25˚C and represent most likely parametric norm.
Note 7: Tested limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 8: The standard deviation, σ, of the flyback pulse period is measured with a HP 53310A Modulation Domain Analyzer. Peak-to-peak jitter of the flyback pulse
is defined by 6σ.
Note 9: A positive phase value represents a phase lead of the flyback pulse peak with reference to the center of H sync.
Note 10: The duty cycle is measured under the conditions of free run with I1 = −100 µA, TFBP = 3 µs and Td = 3.5 µs where TFBP and Td are the flyback pulse width
and the turn off delay of the H deflection output transistor respectively.
Note 11: TH is defined as the total time of one horizontal line.
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Test Circuit
DS012917-2
FIGURE 2.
System Block Diagram
DS012917-3
FIGURE 3.
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4
DRIVE output (pin 7) is latched high. VCC has to be reduced
to below approximately 2V to clear the latched condition, i.e.,
power must be turned off. See Figure 7 for the input schematic.
Pin 6 — FLYBACK: Input pin for phase detector 2. For best
operation, the flyback peak should be at least 5V but not
greater than VCC. Any pulse width greater than 1.5 µs is acceptable. See Figure 8 for the input schematic.
Pin 7 — H DRIVE: This is an open-collector output which
provides the drive pulse for the high power deflection circuit.
The pulse duty cycle is controlled by pin 4. Polarity convention: Horizontal deflection output transistor is on when H
DRIVE OUT is low. See Figure 9 for the output schematic.
Pin 8 — GND: System ground. For best jitter performance,
all bypass capacitors should be connected to this pin via
short paths.
Pin 9 — PD2 FILTER: The low-pass filter cap of between
0.01 µF to 1 µF for the output of phase detector 2 is connected from this pin to pin 8 (GND) via a short path. A
smaller value increases the response.
Pin 10 — PHASE: A DC control voltage applied to this pin
sets the phase of the flyback pulse with respect to the center
of H sync. See Figure 10 for the input schematic.
Pin 11 — FVC FILTER: A 1 µF capacitor is connected from
this pin to pin 8 (GND) via a short path.
Pin 12 — PD1 OUT/VCO IN: Phase detector 1 has a gated
charge pump output which requires an external low-pass filter. For best jitter performance, the filter should be grounded
to pin 8 (GND) via a short path. If a voltage source is applied
to this pin, the phase detector is disabled and the VCO can
be controlled directly.
Pin 13 — VREF: This is the decoupling pin for the internal
8.2V reference. It should be decoupled to pin 8 (GND) via a
short path with a cap of at least 470 µF. Do not load this pin.
Pin 14 — VCC: 12V nominal power supply pin. This pin
should be decoupled to pin 8 (GND) via a short path with a
cap of at least 47 µF.
Pin Descriptions
See Figure 4 through Figure 10 for input and output schematics.
Pin 1 — fMIN: A resistor from this pin to ground sets the free
run frequency of the LM1290. The free run frequency should
be set typically as:
fMIN = 0.85(fMINLOCK) − 2 kHz
where fMINLOCK is the minimum lock frequency required for
the application. The resistance required to set this frequency
is approximately:
For example, to find RMIN for VGA which has fMINLOCK =
31.469 kHz,
fMIN = 0.85(31.469 kHz) − 2 kHz = 24749
Rounding to the closest standard 1% resistor gives RMIN =
21.5 kΩ.
Pin 2 — H/HV POLARITY: A 0.1 µF capacitor is connected
from this pin to ground for detecting the polarity of H/HV sync
at pin 3. A low logic level at pin 2 indicates active-high H/HV
sync to pin 3, a high level indicates active-low. See Figure 4
for the output schematic.
Pin 3 — H/HV SYNC: This input pin accepts DC-coupled H
or composite sync of either polarity. For best noise immunity,
a resistor of 2 kΩ or less should be connected from this pin
to pin 8 (GND) via a short path. See Figure 5 for the input
schematic.
Pin 4 — DUTY CYCLE: A DC voltage applied to this pin sets
the duty cycle of the H DRIVE output (pin 7), with a range of
approximately 30% to 70%. 2V sets the duty cycle to approximately 50%. See Figure 6 for the input schematic.
Pin 5 — X-RAY: This pin is for monitoring CRT anode voltage. If the input voltage exceeds an internal threshold, H
Input/Output Schematics
DS012917-5
DS012917-4
FIGURE 5.
FIGURE 4.
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Input/Output Schematics
(Continued)
DS012917-6
FIGURE 6.
DS012917-9
FIGURE 9.
DS012917-7
FIGURE 7.
DS012917-10
FIGURE 10.
DS012917-8
FIGURE 8.
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Consider a scanning mode transition at t = 0 from f1 to f2.
The VCO frequency as a function of time, fVCO(t), is described by the equation,
Application Hints
1.
Phase Control for Geometry Correction: Pin 10
(PHASE) is designed to control static phase (picture
horizontal position) as well as dynamic phase for geometry correction. Complete control of static and dynamic
phase can be achieved by superposing a correction
waveform (Sawtooth and/or parabola) on the DC control
voltage at pin 10 (see Figure 12).
2. Programmable Frequency Ramping: H frequency
transitions from high to low present a special problem for
deflection output stages without current limiting. If, during such a transition, the output transistor on-time increases excessively before the B+ voltage has decreased to its final level, then the deflection inductor
current ramps too high and the induced flyback pulse
can exceed the breakdown voltage, BVCEX, of the output
transistor. To prevent this, the rate of change of the VCO
frequency must be limited.
fVCO(t) ≅ f 1 + (f 2 − f 1) (1 – exp (−t /τ)),
where τ = 40 x 103 x CFVC.
The above equation can be used to predict VCO behavior during frequency transitions, but in practice the value
of CFVC is most easily determined empirically. In general,
large values minimize the chance of exceeding BVCEX,
but generate long PLL capture times.
3. Phase Voltage Range vs Delay Time: The recommended phase voltage range to use on pin 10 (PHASE)
depends on the delay time of the deflection output stage.
Delay time is defined as the time from the rising edge of
H Drive to the center of flyback. For best performance
the phase voltage range should be in the unshaded area
of Figure 11.
Recommended Phase Voltage for 640 x 480 @ 60 Hz
DS012917-11
FIGURE 11.
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Typical Application
DS012917-12
*Actual value depends on the application and the ambient noise level inside the monitor.
FIGURE 12.
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LM1290 Autosync Horizontal Deflection Processor
Physical Dimensions
inches (millimeters) unless otherwise noted
Order Number LM1290N
NS Package Number N14A
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