diff --git a/boards/arm/mimxrt685_evk/Kconfig.defconfig b/boards/arm/mimxrt685_evk/Kconfig.defconfig
index d613869..8eab98d 100644
--- a/boards/arm/mimxrt685_evk/Kconfig.defconfig
+++ b/boards/arm/mimxrt685_evk/Kconfig.defconfig
@@ -8,6 +8,12 @@
 config BOARD
 	default "mimxrt685_evk_cm33"
 
+config XTAL_SYS_CLK_HZ
+	default 24000000
+
+config SYSOSC_SETTLING_US
+	default 260
+
 if PINMUX_MCUX_LPC
 
 config PINMUX_MCUX_LPC_PORT0
diff --git a/boards/arm/mimxrt685_evk/doc/index.rst b/boards/arm/mimxrt685_evk/doc/index.rst
index 36c3136..cbefa00 100644
--- a/boards/arm/mimxrt685_evk/doc/index.rst
+++ b/boards/arm/mimxrt685_evk/doc/index.rst
@@ -119,14 +119,14 @@
 System Clock
 ============
 
-The MIMXRT685 SoC is configured to use the internal FRO at 48MHz as a source for
-the system clock. Other sources for the system clock are provided in the SOC,
-depending on your system requirements.
+The MIMXRT685 SoC is configured to use the main system PLL at 250MHz
+as a source for the system clock. Other sources for the system clock
+are provided in the SOC, depending on your system requirements.
 
 Serial Port
 ===========
 
-The MIMXRT685 SoC has 8 FLEXCOMM interfaces for serial communication.  One is
+The MIMXRT685 SoC has 8 FLEXCOMM interfaces for serial communication. One is
 configured as USART for the console and the remaining are not used.
 
 Programming and Debugging
diff --git a/boards/arm/mimxrt685_evk/mimxrt685_evk_cm33_defconfig b/boards/arm/mimxrt685_evk/mimxrt685_evk_cm33_defconfig
index 0038347..d1ba8ff 100644
--- a/boards/arm/mimxrt685_evk/mimxrt685_evk_cm33_defconfig
+++ b/boards/arm/mimxrt685_evk/mimxrt685_evk_cm33_defconfig
@@ -14,8 +14,7 @@
 CONFIG_CORTEX_M_SYSTICK=y
 CONFIG_GPIO=y
 CONFIG_PINMUX=y
-CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=48000000
-
+CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=250105263
 # Enable TrustZone-M
 CONFIG_TRUSTED_EXECUTION_SECURE=y