Power Management
The Power Management implements all the internal power circuitry (regulators, links…)
as well as power failure detector and reset circuitry.
Power Supply
The AT85C51SND3B3 embeds the regulators and a DC to DC step-up convertor to be
able to operate from either USB power supply (5V nominal) or from a single cell battery
such as AAA battery.
The AT85C51SND3B1 and AT85C51SND3B2 embed the regulators to be able to oper-
ate from either USB power supply (5V nominal) or from an external 3 volts supply.
Figure 5. Power Supply Diagram
PSTA.7
UVDET
UVCC
UVSS
HVDD
VSS
3 V
Regulator
To Internal Core
RLVDD
1.8 V
Regulator
PSTA.6
HVDET
Optional
Connection(1)
DCPBST
PCON.5
DCPWR
DCLI
DCEN
PCON.3
1.8 V DC-DC
LVDD
BVDD
BVSS
Battery Monitor
VBAT
Note:
1. External connection mandatory when 1.8V DC-DC is used.
Regulators
The high voltage regulator supplies power to the external devices through HVDD power
pin. Its nominal voltage output is 3V.
The low voltage regulator supplies power to the internal device and external devices
through RLVDD power pin. Its nominal voltage output is 1.8V.
Figure 6 shows how to connect external components, capacitors value along with power
characteristics are specified in the section “DC characteristics”.
18
AT85C51SND3Bx
7632A–MP3–03/06
ATMEL [ ATMEL ]
