Maxim Integrated MAXQ7667 - Manual (Page 261)

15.2.6 RC Oscillator Trim Register (RCTRM)
Register Description: RC Oscillator Trim Register
Register Name: RCTRM
Register Address: Module 01h, Index 17h
Bits 15 to 8: Reserved
Bits 7 to 0: Trim Codes for the BIAS Block (RCTRM[7:0])
15.3 System Clock Generation
15.3.1 Internal RC Oscillator
The internal RC oscillator is the default system clock source for the MAXQ7667, since the XTRC defaults to 0 on a power-on/brownout
reset. No external clock or crystal is required for the RC oscillator.
The RC oscillator provides a low-cost system solution that eliminates the need for an external high-frequency clock source for high-
speed operation.
The power-on/brownout reset circuitry holds the device in reset at power-up, while the DVDD supply crosses above the reset thresh-
old voltage, and the internal free-running RC oscillator starts running at a default value of approximately 13.5MHz, and a 16-bit power-
up timer is enabled. After the power-on/brownout circuitry releases the reset, the microcontroller jumps to the program in the utility ROM
at location 8000h.
The RCMD (CKCN.5) bit set to 1 indicates that the RC oscillator is providing the system clock. Since the default clock source at power-
up is the RC clock, RCMD is set to 1. (RCMD = 0 indicates that it is the external crystal or the clock providing the system clock).
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MAXQ7667 User’s Guide
Bit # 15 14 13 12 11 10 9 8
Name — — — — — — — —
Reset 0 0 0 0 0 0 0 0
Access r r r r r r r r
Bit # 7 6 5 4 3 2 1 0
Name RCTRM7 RCTRM6 RCTRM5 RCTRM4 RCTRM3 RCTRM2 RCTRM1 RCTRM0
Reset 0 0 0 0 0 0 0 0
Access r r r r r r r r
r = read (Writeable only when TME = 1).
Note: RCTRM is cleared to 00h on power-on reset, then initialized to a value stored within the flash information block.