diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/stm32h7_mcuconf.h b/libraries/AP_HAL_ChibiOS/hwdef/common/stm32h7_mcuconf.h
index 51df9c543f238..a5d70ba9121b3 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/stm32h7_mcuconf.h
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/stm32h7_mcuconf.h
@@ -86,6 +86,8 @@
 #define STM32_PWR_CR2                       (PWR_CR2_BREN)
 #ifdef SMPS_PWR
 #define STM32_PWR_CR3                       (PWR_CR3_SMPSEN | PWR_CR3_USB33DEN)
+#elif defined(SMPS_PWR_EXT_1V8)
+#define STM32_PWR_CR3                       (PWR_CR3_SMPSLEVEL_0 | PWR_CR3_SMPSEXTHP | PWR_CR3_SMPSEN | PWR_CR3_LDOEN | PWR_CR3_USB33DEN)
 #else
 #define STM32_PWR_CR3                       (PWR_CR3_LDOEN | PWR_CR3_USB33DEN)
 #endif