Rainbow Electronics AT83C26 - Manual (Page 60)

60
7511B–SCR–10/05
AT83C26
Reset value = 0x 0000 0000
Table 42. DCDCB (Config Interface B Byte 2)
7 6 5 4 3 2 1 0
SHUTDOWNB VDCB_INT VDCB_OK 0 ICCADJB STEPREGB VDCB1 VDCB0
Bit Number Bit Mnemonic Description
7 SHUTDOWNB
Shutdown DCDCB
Set this bit to reduce the power consumption. An automatic de-activation sequence will be done.
Clear this bit to enable VDCB.
The reset value is 0.
6 VDCB_INT
DC/DC B voltage interrupt
This bit is set when VCARD_OKB bit is set.
This bit is cleared when read by the micro controller.
The reset value is 0.
5 VDCB_OK
DC/DC B Voltage Status
This bit is set by the DCDC when the output voltage remains within the voltage range specified by VDCB[1:0]
bits. It is recommended to wait for this bit to be set before activating a card at the corresponding voltage.
It is cleared otherwise.
The reset value is 0.
4 0 This bit must be always at 0.
3 ICCADJB
CI
CC
overflow adjust
This bit controls the DC/DCB sensitivity to any overflow current.
Set this bit to decrease the DC/DCB sensitivity (CI
CC_ovf
is increased by about 20%).
Clear this bit to have a normal configuration.
The reset value is 0.
2 STEPREGB
DC/DC B Step-up Regulator Mode
Set this bit to permanently disable the step-up converter (CVCC is stable only if VCC is sufficiently higher
than CVCC). This bit must always be set if no external self is used.
Clear this bit to enable the automatic step-up converter (CVCC is stable even if VCC is not higher than
CVCC).
The reset value is 0.
1-0 VDCB[1:0]
DC/DC B Voltage Selection
VDCB[1:0] = 00: 0V
VDCB[1:0] = 01: 2.2V (for Class C)
VDCB[1:0] = 10: 3.2V (for Class B and C)
VDCB[1:0] = 11: 5.2V (for Class A, B and C)
No card deactivation is performed when the voltage is changed. The voltage must be set higher than the
voltage of all the active cards. If a Class A card is deactivated and the remaining cards are in Class B or C,
VDCB can be reduced to 3.2V to reduce power consumption. If a Class B card is deactivated and the
remaining cards are in Class C, VDCB can be reduced to 2.2V to reduce power consumption.It is not reset
when cards are deactivated. It must be cleared by the micro controller to stop DC/DC B (e.g. to reduce power
consumption).
The reset value is 00.