HMP8170 Datasheet, PDF (31/33 Pages) Intersil Corporation – NTSC/PAL Video Encoder

HMP8170, HMP8171, HMP8172, HMP8173
FERRITE
BEAD
BULK AREA
CAPACITOR
VCC
815841/871x56A
LP
FILTERS
ANALOG
CONN.
GND
VAA
PCB
FIGURE 26A. V_CC AND V_AA PLANES
815841/871x56A
LP
FILTERS
ANALOG
CONN.
PCB
FIGURE 26B. COMMON GROUND PLANE
FIGURE 26. EXAMPLE POWER AND GROUND PLANES
For proper operation, power supply decoupling is required. It
should be done using a 0.1µF ceramic capacitor in parallel
with a 0.01µF chip capacitor for each group of V_AA pins to
ground. These capacitors should be located as close to the
V_AA and GND pins as possible, using short, wide traces.
If a separate linear regulator is used to provide power to the
HMP817x power plane, the power-up sequence should be
designed to ensure latchup will not occur. A separate linear
regulator is recommended if the power supply noise on the
VAA pins exceeds 200mV. About 10% of the noise (that is
less than 1MHz) on the VAA pins will couple onto the analog
outputs.
External Reference Voltage
If an external reference voltage is used, its circuitry should
receive power from the same plane as the HMP817x. The
external VREF must also be stable and well decoupled from
the power plane. An example VREF circuit using a band gap
reference diode is shown in Figure 27.
31