
1-135
Mitsubishi microcomputers
M30240 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Preliminary Specifications REV. E
Specifications in this manual are tentative and subject to change
Frequency Synthesizer Interface and DC-DC Converter
5.1.2 Set up of Frequency Synthesizer and DC-DC Converter
Figure 1.118: PLL, DC-DC Converter and USB Functional Block Diagram
A functional block diagram of the USB system on the M30240 which shows how the control signals
affect operation is given in Figure 1.118
5.1.2.1 Set up after Hardware Reset
A Hardware Reset occurs when either the RESET pin is brought low for more than 2
μ
s or an invalid
opcode is fetched by the CPU. The frequency synthesizer (PLL) and DC-DC converter should be set
up as follows in the Hardware Reset routine (see Figure 1.119),
Power up the M30240 and other components on the peripheral device for less than 100 mA opera-
tion. The current limit only applies for bus powered devices.
Configure the PLL for 48MHz f(VCO) operation.
Enable the PLL by setting FSE (bit 0 of the Frequency Synthesizer Control Register (FSC)) to a “1”,
then wait for 2 ms.
Check the lock status bit (LS, bit 7 of FSC).
If the bit is a “1”, go on.
If the bit is a “0”, wait 0.1 ms longer and then re-check the bit.
Enable the DC-DC converter in high current mode by setting USBC4 (bit 4 of the USB Control Reg-
ister (USBC)) to a “1” and keeping USBC3 (bit 3 of USBC) a “0”. High current mode should always
be used during normal USB operation. Low current mode should only be used during a USB sus-
pend.
Wait (C + 1)ms (where C equals the external capacitance connected to the Ext Cap pin in
μ
F) for
the voltage on Ext Cap to reach a steady state voltage of approximately 3.3V. (Since the D+ pullup
is connected to the Ext Cap pin, the upstream hub will detect that the peripheral device has been
plugged in once the voltage on D+ reaches approximately 2.0 V.)
Example: A 2.2
μ
F
capacitor connected to Ext Cap requires 3.2 ms for the voltage on Ext Cap to be stable.
33
33
D+
D-
USB FCU
2.2
μ
F
0.1
μ
F
Ext Cap
Frequency
Synthesizer
enable
f(Xin)
FSE
LS
1
USB Transceiver
DC-DC Converter
USBC3
USBC4
USBC7
USBC7
USBC5
USBCLK
(48MHz)
lock
enable
enable
(enable)
(enable)
enable
current
mode