PS No. 5765-14/14
LA7567N, 7567NM
Notes on VCO Tank Circuits
Built-in capacitor VCO tank circuits
When the power is turned on, the heat generated by the IC is transmitted through the printed circuit board to the VCO
tank circuit. At this point, the VCO coil frame functions as a heat sink and the IC heat is dissipated. As a result, it
becomes more difficult to transmit heat to the VCO tank circuit's built-in capacitor, and the influence of drift at power
on is reduced. Therefore, it suffices to design the circuit so that the coil and capacitor thermal characteristics cancel.
Ideally, it is better to use a coil with a core material that has low temperature coefficient characteristics.
External capacitor VCO tank circuits
When an external capacitor is used, heat generated by the IC is transmitted through the printed circuit board directly to
the VCO tank circuit external capacitor. While this capacitor is heated relatively early after the power is turned on, the
coil is not so influenced as much by this heat, and as a result the power-on drift is increased. Accordingly, a coil whose
core material has low temperature coefficient characteristics must be used. It is also desirable to use a capacitor with
similarly low temperature coefficient characteristics.
Note: Applications that use an external capacitor here must use a chip capacitor. If an ordinary capacitor is used,
problems such as the oscillator frequency changing with the capacitor orientation may occur.
This catalog provides information as of May, 1998. Specifications and information herein are subject to change
without notice.
s No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace
equipment, nuclear power control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of
which may directly or indirectly cause injury, death or property loss.
s Anyone purchasing any products described or contained herein for an above-mentioned use shall:
Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and
distributors and all their officers and employees, jointly and severally, against any and all claims and litigation and all
damages, cost and expenses associated with such use:
Not impose any responsibility for any fault or negligence which may be cited in any such claim or litigation on
SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors or any of their officers and employees
jointly or severally.
s Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for
volume production. SANYO believes information herein is accurate and reliable, but no guarantees are made or implied
regarding its use or any infringements of intellectual property rights or other rights of third parties.