2.2
Output voltage selection
The
provides up to eight different output voltage options. The combination of its three digital input
selectors (SELx) determines the output voltage according to the following truth table.
Table 4.
SELx pins: truth table
V
O
(volt)
SEL1
SEL2
SEL3
5
1
1
1
3.3
1
1
0
2.8
1
0
1
2.5
1
0
0
1.8
0
1
1
1.5
0
1
0
1.2
0
0
1
0.8 (default)
0
0
0
The SELx pin configuration is acquired at the device startup (about 500 microseconds). Once the configuration is
set, the output voltage cannot be changed until the next EN pin transition. If all SELx pins are left unconnected,
the default configuration is selected.
2.3
Watchdog (for the AEK-POW-LDO01J only)
The watchdog is an automotive safety mechanism used to monitor a continuous connection with an external
MCU.
The watchdog signal (generated by the MCU and applied to the
WI pin) is a square wave
with a duty cycle equal to 50%. Its frequency value depends on both the output voltage and the chosen C4
capacitor value (see the
The table below lists the watchdog frequencies (Hz) related to the selectable output voltage.
Table 5.
WI frequencies in Hz
V
O
(volt)
WI frequency (Hz)
5
172
3.3
114
2.8
94
2.5
76
1.8
55
1.5
49
1.2
42
0.8 (default)
28
UM3028
Output voltage selection
UM3028
-
Rev 1
page 6/37
