Power Supply Module - Renesas M3A-HS85 User Manual

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2.6 Power Supply Module

In M3A-HS85, 5V power is input to the board and 3.3V is generated by using a regulator. The regulator used is
output voltage variable type and given voltage value can be generated by changing the resistance value.
5V power can be supplied from DC stabilized power supply (via power supply connector (J4)) and AC adapter (via
DC power supply jack (J7)).
SH7285 system power supply (VCC) can be switched to 3.3V/5V by setting 3V/5V select jumper (JP1)(Initially it is
set to 5V). When VCC is switched, please note the points shown as follows.
• When 5V is set in the state that SRAM or SDRAM is mounted, the voltage that exceeds the maximum rating is
supplied from the address line, data line, and control line to SDRAM or SRAM, and devices could be destroyed. Thus,
using like this must be avoided.
(3.3V is supplied to 3V system device such as SRAM and SDRAM even when 5V is set.)
By setting jumpers, system power (VSS), A/D power (AVCC), AVREF power, and USB power (DrVCC) of SH7285
can be individually supplied from external power supply.
Figure 2.6.1 shows the block diagram of M3A-HS85 power supply circuit.
J4
Power
connector
DC5V
input
J7
DC power jack
Rev.1.04 2008.7.10
REJ10J1564-0104
Extension connector
5VCC
5VCC
Power switch
5VCC
5VCC 5V
3.3V
Extension connector
Figure 2.6.1 Block Diagram of Power Supply Circuit
AVCC
J8 connector
JP4
AVREF
J8 connector
JP5
External
power supply
3.3V/5V select
jumper (JP1)
1
2
JP
3
VCC
JP2
3VCC
JP3
SRAM SDRAM
It is not initially mounted.
Mountable only for 3.3V operation
Functional Overview
2.6 Power Supply Module
SH7285
AVCC
AVREF
VCC
VCC_CPU
DrVCC
(USB power supply)
External
power supply
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