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Integrated voltage regulator<br />
<strong>STM32W108C8</strong><br />
7 Integrated voltage regulator<br />
The <strong>STM32W108C8</strong> integrates two low dropout regulators to provide 1.8 V and 1.25 V<br />
power supplies. The 1V8 regulator supplies the analog and memories, and the 1V25<br />
regulator supplies the digital core. In deep sleep the voltage regulators are disabled.<br />
When enabled, the 1V8 regulator steps down the pads supply voltage (VDD_PADS) from a<br />
nominal 3.0 V to 1.8 V. The regulator output pin (VREG_OUT) must be decoupled externally<br />
with a suitable capacitor. VREG_OUT should be connected to the 1.8 V supply pins VDDA,<br />
VDD_RF, VDD_VCO, VDD_SYNTH, VDD_IF, and VDD_MEM. The 1V8 regulator can<br />
supply a maximum of 50 mA.<br />
When enabled, the 1V25 regulator steps down VDD_PADS to 1.25 V. The regulator output<br />
pin (VDD_CORE, (Pin 17) must be decoupled externally with a suitable capacitor. It should<br />
connect to the other VDD_CORE pin (Pin 44). The 1V25 regulator can supply a maximum of<br />
10 mA.<br />
The regulators are controlled by the digital portion of the chip as described in Section 6:<br />
System modules.<br />
Table 20.<br />
1.8 V integrated voltage regulator specifications<br />
Parameter Min. Typ. Max. Units Comments<br />
Supply range for regulator 2.1 3.6 V VDD_PADS<br />
1V8 regulator output -5% 1.8 +5% V<br />
1V8 regulator output after reset -5% 1.75 +5%<br />
1V25 regulator output -5% 1.25 +5% V<br />
1V25 regulator output after reset -5% 1.45 +5%<br />
1V8 regulator capacitor 2.2 µF<br />
Regulator output after<br />
initialization<br />
Regulator output after<br />
reset<br />
Regulator output after<br />
initialization<br />
Regulator output after<br />
reset<br />
Low ESR tantalum<br />
capacitor<br />
ESR greater than 2 Ω<br />
ESR less than 10 Ω<br />
De-coupling less than100<br />
nF ceramic<br />
1V25 regulator capacitor 1.0 µF Ceramic capacitor (0603)<br />
1V8 regulator output current 0 50 mA Regulator output current<br />
1V25 regulator output current 0 10 mA Regulator output current<br />
No load current 600 µA<br />
No load current<br />
(bandgap and regulators)<br />
1V8 regulator current limit 200 mA Short circuit current limit<br />
1V25 regulator current limit 25 mA Short circuit current limit<br />
53/215 Doc ID 018587 Rev 2
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