Rainbow Electronics AT91CAP9S250A - Manual (Page 255)

255
6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
24.4.4 Power Management
24.4.4.1 Standby Mode
This mode is activated by programming low power command bits (LPCB) to 1 ( See “LPCB: Low
Power Command Bit” on page 262. )
Standby mode is used when there is no access to the Cellular Ram device. In this mode, power
consumption is reduced, BCCK pin is low and ce pin is high.
When the device is in standby mode, address inputs and data inputs/outputs are internally iso-
lated from external influence.
The BCRAMC leaves standby mode as soon as the Cellular Ram device is selected and returns
to standby mode as soon as the Cellular Ram device is no longer selected.
Figure 24-12. Standby Mode Entry/Exit
24.4.4.2 Deep Power Down Mode (DPD)
This mode is selected by programming the LPCB field to 2 in the BCRAMC Low Power Register
(
See “LPCB: Low Power Command Bit” on page 262. ). As soon as LPCB field is programmed
and no access in Cellular Ram is pending, the Refresh Configuration Register is automatically
accessed and DPD mode is enabled.
When this mode is activated, all internal voltage generators inside the Cellular Ram are stopped
and all data is lost. Only the register values of the Bus Configuration Register and Refresh Con-
figuration Register are kept valid during deep power down mode.
To leave this mode, the LPCB field must be programmed to 0 in the BCRAMC Low Power Reg-
ister. As soon as the LPCB field is programmed and Cellular Ram access is pending, the
Refresh Configuration Register is automatically accessed and the DPD bit is disabled.
No command should be applied during 150 µs, before re-entry in idle or standby mode.
A[27:0]
BCADV
BCCS
BCCK
BCCRE
D[31:0]
BCOE
BCWE
BCOWAIT
Enter Standby Mode Exit Standby Mode