
Revision 1.1
18 - 32
AS8530
Datasheet - Application In form atio n
8 Application Information
8.1 Initialization
When the power supply is switched on, if VSUP > VSUVR_OFF, RESET_VSUP_N becomes inactive (high). After this, the voltage regulator
starts with a default LDO output setting of 3.3V and Vuvr_off setting of 2.75V. If VCC > Vuvr_off (2.75V), active-low PORN_2_OTP is generated.
The rising edge of PORN_2_OTP loads contents of fuse onto the OTP latch after load access time TLoad. LOAD_OTP_IN_PREREG signal loads
contents of OTP latch onto the pre-regulator domain register. This register gives actual settings of LDO, Vuvr_off and Reset Timeout period TRes.
This is done because the OTP block is powered by the VCC. If VCC > Vuvr_off (phase 2), Reset timeout is restarted. RESET signal is de-
asserted after Reset Timeout period TRes (phase 2) and then device enters into normal mode. The circuit initializes correctly also for very slow
ramp on VSUP (of the order of 0.5V/min).
Figure 7. Initialization Sequence for AS8530
LDO
Off
LDO On
Vuvr_off = 2.75V, LDO setting = 3.3V
tRES = 4msec
LDO On
Vuvr_off = from OTP Block, LDO setting = from OTP Block
tRES = from OTP Block
VCC
VSUP
Device
Settings
RESET_VCC_N
RESET_VSUP_N
PORN_2_OTP
LOAD_OTP_IN_PREREG
RESET
Vuvr_off
Vsuvr_off
6 Cycles of
RC-Oscillator
PHASE 1
PHASE 2
If Phase 1 POR threshold == Phase 2 POR threshold
Tres = Reset Timeout from OTP Block
If Phase 1 POR threshold != Phase 2 POR threshold
Tres = Reset Timeout from OTP Block
Vuvr_off