Maxim-integrated MAXQ7667 Bedienungsanleitung PDF herunterladen (Seite 261)

15.2.6 RC Oscillator Trim Register (RCTRM)

egister Name:

CTRM

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 cir

cuitr

y r

eleases 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).

15-9 __________________________________________________________________________________________________________

MAXQ7667 User’s Guide

Bit #

15 14 13 12 11 10 98

Name — — — — — — — —

eset 0 0 0 0 0 0 0 0

ccess r r r r r r r r

it #

76543210

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.

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Maxim-integrated MAXQ7667 Bedienungsanleitung Seite 261