
1-30
dUnde
Specifications in this manual are tentative and subject to change
Rev. G
Voltage Down Converter
MITSUBISHI MICROCOMPUTERS
M30222 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Voltage Down Converter
The Voltage Down Converter (VDC) is a bandgap reference based voltage regulator used for generating
a low-voltage supply. The VDC block inputs the external supply V
CC
(up to 5.5 volts) and generates a 3.3-
volt (nominal) supply (VDD). Table 1.14 describes the specified voltage regulation. The VDC is pro-
grammable in terms of drive limit and power level. In low power mode, the VDC can source up to 20mA
and uses less than 10uA bias current. In high-power mode, the VDC can source up to 200mA. There is
a programmable option to limit the current of the VDC in high-power mode to about 80mA. The VDC
default state (from reset) is high-power mode with current limiting enabled. The current limiting is en-
abled at reset in order to avoid a large in-rush current to an external hold capacitor (required) on the
VDC pin. Once the external hold capacitor is charged, the current limiter can be disabled in software.
Figures 1.17 and 1.18 describe the programmable features of the VDC. The external hold capacitor is
required to stabilize the VDC and to minimize voltage ripple on the 3.3 volt supply during operation.
Table 1.15 describes the external hold capacitor requirements.
Table 1.15. Required External Components
Figure 1.17. VDC Control/Status Register
Component
Value
0.1
μ
F +/- 20%
Material
External Hold Capacitor
Ceramic
Table 1.14. VDC voltage regulations
Signal
Package Supply (Vcc)
Description
Range: 2.7v to 5.5v (input to VDC)
Internal Supply (Vdd)
3.3v (nominal) +/- 10% (output from VDC) OR
Vcc - 200mV @ Icc
(AVG)
<15 mA (Note)
Note: Whichever is smaller
Voltage Down Converter control register
Symbol
VDCC
Address
0018
16
When reset
XXX00X00
2
b7
b6
b5
b4
b3
b2
b1
b0
0 : High power
1 Low power
HPOWER
VDCC0
0 1 : Reserved
1 0 : Reserved
1 1 : VDC disabled
b1 b0
VDCC1
ILIMEN
Nothing is assigned. Write "0" when writing to these bits. If read, the
value is indeterminate.
Function
Bit symbol
W
R
_ _
_
0 : Current limit enabled
1 : Current limit disabled
Nothing is assigned. Write "0" when writing to this bit. If read, the
value is indeterminate.
_