Rainbow Electronics T5761 - Manual (Page 24)

24
T5760/T5761
4561B–RKE–10/02
Conservation of the
Register Information
The T5760/T5761 implies an integrated power-on reset and brown-out detection
circuitry to provide a mechanism to preserve the RAM register information.
According to Figure 30 , a power-on reset (POR) is generated if the supply voltage V
S
drops below the threshold voltage V
ThReset
. The default parameters are programmed into
the configuration registers in that condition. Once V
S
exceeds V
ThReset
the POR is
canceled after the minimum reset period t
Rst
. A POR is also generated when the supply
voltage of the receiver is turned on.
To indicate that condition, the receiver displays a reset marker (RM) at Pin DATA after a
reset. The RM is represented by the fixed frequency f
RM
at a 50% duty-cycle. RM can be
canceled via a Low pulse t1 at Pin DATA. The RM implies the following characteristics:
• f
RM
is lower than the lowest feasible frequency of a data signal. By this means, RM
cannot be misinterpreted by the connected microcontroller.
• If the receiver is set back to polling mode via Pin DATA, RM cannot be canceled by
accident if t1 is applied according to the proposal in the section “Programming the
Configuration Registers”.
By means of that mechanism the receiver cannot lose its register information without
communicating that condition via the reset marker RM.
Figure 30. Generation of the Power-on Reset
V
S
POR
Data_out (DATA)
1 / f
RM
t
Rst
V
ThReset
X