UM10346_1
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 01 — 2 November 2009
36 of 132
NXP Semiconductors
UM10346
LPC980/982 User manual
These 3 functions are disabled in Power-down mode and Total Power-down mode. In
normal or idle mode, BOD reset and BOD flash are always on and can not be disabled in
software. BOD interrupt will generate an interrupt and could be enabled or disabled in
software.
BOD reset and BOD interrupt, each has 6 levels. BOE0 to BOE2 (UCFG1[3:5]) are used
as trip point configuration bits of BOD reset. BOICFG0 to BOICFG2 in register BODCFG
are used as trip point configuration bits of BOD interrupt. BOD reset voltage should be
lower than BOD interrupt trip point.
and
gives BOD trip points
configuration.
In Power-down mode (PMOD1/PMOD0 = ‘10’) or total Power-down mode
(PMOD1/PMOD0 = ‘11’), the circuitry for the Brownout Detection is disabled for lowest
power consumption. When PMOD1/PMOD0 is not equal to ‘10’ or ‘11’, BOD reset is
always on and BOD interrupt is enabled by setting BOI (PCON.4) bit. Please refer to
for BOD reset and BOD interrupt configuration. BOF bit (RSTSRC.5), BOD reset
flag is default as '0' and is set when BOD reset is tripped. BOIF bit (RSTSRC.6), BOD
interrupt flag is default as '0' and is set when BOD interrupt is tripped.
BOD FLASH is used for flash program/erase protection. BOD FLASH is always on, except
in power-down or total power down mode (PCON.1=1). It can not be disabled in software.
BOD FLASH has only 1 trip voltage level of 2.4 V. When voltage supply is lower than
2.4 V, the BOD FLASH is tripped and flash program/erase is blocked.
If brownout detection works, the brownout condition occurs when VDD falls below the
brownout falling trip voltage and is negated when VDD rises above the brownout rising trip
voltage.
For correct activation of brownout detect, the VDD rise and fall times must be observed.
Please see the data sheet for specifications.
Table 18.
BOD reset Trip points configuration
BOE2
(UCFG1.5)
BOE1
(UCFG1.4)
BOE0
(UCFG1.3)
BOD Reset
Fall
Rise
0
0
0
reserved
reserved
0
0
1
reserved
reserved
0
1
0
2.25V
2.4V
0
1
1
2.55V
2.7V
1
0
0
2.85V
3.0V
1
0
1
3.15V
3.3V
1
1
0
3.85V
4V
1
1
1
4.05V
4.2V