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LA7837 Schematic ( PDF Datasheet ) - Sanyo

Teilenummer LA7837
Beschreibung Vertical Deflection Circuit with TV / CRT Display Drive
Hersteller Sanyo
Logo Sanyo Logo 




Gesamt 9 Seiten
LA7837 Datasheet, Funktion
Ordering number:ENN3313C
www.DataSheet4U.com
Monolithic Linear IC
LA7837, 7838
Vertical Deflection Circuit
with TV/CRT Display Drive
Overview
The LA7837, 7838 are vertical deflection output ICs de-
veloped for use in high-grade TVs and displays. The inter-
lace and crossover distortion responses, in particular, have
been greatly improved, allowing excellent picture quality
on large size televisions and high precision interlace mode
displays.
Also, pulse signals can be used for input signals due to the
on-chip sawtooth wave generating circuit and driver cir-
cuit. Further, the DC and AC feedback circuit can be formed
with these ICs alone, simplifying pattern design of sets and
ensuring stable performance. All of the functions in a color
TV signal system can be processed by connecting these
ICs with SANYO’s single-chip IC LA7670 series (NTSC)
and LA7680/85 series (PAL/NTSC) (VIF/SIF, video,
chroma, deflection).
The LA7837 has a maximum deflection current of 1.8Ap-
p, making it appropriate for use in portable to mid-size tele-
visions.
The LA7838 has a miximum deflection current of 2.2Ap-
p, so it can be used for large size sets, and can drive from
33 to 37 inches.
Package Dimensions
unit:mm
3107-SIP13H
[LA7837, 7838]
25.6
3.4 10.0
2.0
2.4
1
0.8 2.0
0.5
13
0.4
1.15 1.2
SANYO : SIP13H
Features
• Low power dissipation due to on-chip pump-up circuit.
• On-chip 50/60Hz vertical size control circuit.
• On-chip sawtooth wave generating circuit.
• On-chip driver circuit.
• Vertical output circuit.
• On-chip thermal protection circuit.
• Excellent interlace response.
• Excellent crossover response.
Any and all SANYO products described or contained herein do not have specifications that can handle
applications that require extremely high levels of reliability, such as life-support systems, aircraft’s
control systems, or other applications whose failure can be reasonably expected to result in serious
physical and/or material damage. Consult with your SANYO representative nearest you before using
any SANYO products described or contained herein in such applications.
SANYO assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges,or other
parameters) listed in products specifications of any and all SANYO products described or contained
herein.
SANYO Electric Co.,Ltd. Semiconductor Company
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110-8534 JAPAN
12501TN (KT)/71693TS/8251TS(KOTO)/2090TA, TS(AF) No.3313–1/9






LA7837 Datasheet, Funktion
LA7837, 7838
Precautions when using with display having short retrace time :
wwTwh.eDavtearStihceaelt4oUu.tcpoumt ICs LA7837, 7838 are appropriate for use in monitors and displays because the interlace and
crossover distortion responses are superior to those of the LA7835, 7836.
However, since the vertical retrace time of displays is shorter than that of TV, the upper portion of the vertical
picture may stretch. This is because the start waveform of the pin 6 sawtooth wave bends, as shown in Fig.4, due to
the diode response of the clamp waveform. If there is not much time difference between T1 ant TR, the upper portion
of the vertical picture will tend to stretch. The use of a circuit as shown in Fig.3 will cause pin 6 waveform start
wave to become linear, so that stretching is suppressed. The example of circuit application shown in Fig.3 does not
use the trigger input circuit (pin 2) and one-shot multivibrator (pin 3) built in the LA7837, 7838 ; the pin 6 sawtooth
wave is controlled by the LA7855, 7856 vertical output pulse.
Therefore, the discharge circuit and clamp circuit are formed by the external Zener diode and transistor TR2.
Fig. 4
Design Example
For 12V pin 1 power supply
On the LA7837, 7838, pin 3 one-shot multivibrator operates when a trigger pulse enters pin 2. During this time, the
sawtooth wave generator discharge circuit and clamp circuit inside pin 6 operate.
The clamp voltage at this time is figured according to this formula :
VCLAMP=5/12 · VCC ........................... ¡
For 12V,
VCLAMP=5 [V]
Therefore, the Zener diode used in Fig.3 must be rated more than 5V (e.g. 5.6V), otherwise the clamp circuit inside
the IC will operate.
For 9V pin 1 power supply
The same as for 12V, according to formula ¡ :
VCLAMP=3.75 [V]
So, that Zener diode must be rated more than 4V (e.g. 4.5V).
No.3313–6/9

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