BC41B143A-DS-001PE Datasheet, PDF (55/102 Pages) List of Unclassifed Manufacturers – BlueCpre 4-ROM Single Chip Bluetooth v2.0 System with EDR

Device Terminal Descriptions
10.2.4 Clock Start-Up Delay
BlueCore4-ROM hardware incorporates an automatic 5ms delay after the assertion of the system clock request
signal before running firmware. This is suitable for most applications using an external clock source. However,
there may be scenarios where the clock cannot be guaranteed to either exist or be stable after this period. Under
these conditions, BlueCore4-ROM firmware provides a software function which will extend the system clock
request signal by a period stored in PSKEY_CLOCK_STARTUP_DELAY. This value is set in milliseconds from
5-31ms.
This PS Key allows the designer to optimise a system where clock latencies may be longer than 5ms while still
keeping the current consumption of BlueCore4-ROM as low as possible. BlueCore4-ROM will consume about
2mA of current for the duration of PSKEY_CLOCK_STARTUP_DELAY before activating the firmware.
Actual Allowable Clock Presence Delay on XTAL_IN vs. PSKey Setting
30.0
25.0
20.0
15.0
10.0
5.0
0.0
0.0
5.0
10.0
15.0
20.0
25.0
30.0
PSKEY_CLOCK_STARTUP_DELAY
Figure 10.5: Actual Allowable Clock Presence Delay on XTAL_IN vs. PS Key Setting
BC41B143A-ds-001Pe
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Production Information
© Cambridge Silicon Radio Limited 2005
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