HD6417660 RENESAS [Renesas Technology Corp], HD6417660 Datasheet - Page 659

• Manufacturer Part Number: HD6417660
• Description: Renesas 32-Bit RISC Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

21.7
The BT of this LSI allows direct connection to the RF IC and thus minimizes the need for
externally connected components.
21.7.1
The clock, which is input from the HD157100NP RF IC or HD157102NP (Renesas) and is used
for the interface with the RF IC, may be used as the main clock of this LSI (see figure 21.2). The
RF IC (Renesas) starts outputting a clock signal after a certain period of time following the
negation of a power-on reset. However, the input of a clock signal to this LSI is required to settle
the oscillation of the on-chip oscillator during reset. For this reason, the LSI’s internal reset signal
is kept at a low level after negation of the external power-on reset signal. The internal reset signal
is only negated after the required period from the application of an external clock signal has
elapsed. The timing chart for this is shown in figure 21.8.
There are two types of the internal reset signals for the USB and the other modules. The required
period of the internal reset signal for the USB being asserted is different from that of the others.
The timing chart is shown in figure 21.8.
Notes: 1. A variable capacitor for frequency adjustment may be placed in the Cin or Cout side
Power-On Reset/Clock-Resume Control Circuit
Power-On Reset
2. The value of the on-chip resistor is Rf = 10 MΩ and RD = 400 kΩ under the typical condition.
3. The values of the Cin and Cout include floating capacitance due to wiring.
4. Since the oscillation stabilization time of the crystal oscillation differs according to the
5. Place the crystal resonator and load capacitance (Cin and Cout) near this LSI (in order to
according to the adjustment range, stability, and so on.
constant of the mounting circuit, floating capacitance, and so on, it should be determined in
consultation with the crystal resonator manufacturer.
prevent operation failure from occurring after a noise is externally inducted to the EXTAL2 and
XTAL2 pins).
Internal LSI
Figure 21.7 Note on Using Crystal Resonator
EXTAL2
Cin
resonator
Crystal
Rf
R
XTAL2
Cout
D
Rev. 1.00, 02/04, page 621 of 804