Compute Module Datasheet

Copyright Raspberry Pi (Trading) Ltd. 2016

9.6

Composite (TV Out)

The TVDAC pin can be used to output composite video (PAL or NTSC). Please route this signal away

from noise sources and use a 75 ohm PCB trace.

Note that the TV DAC is powered from the VDAC supply which must be a clean supply of 2.5-2.8V. It

is recommended users generate this supply from 3V3 using a low noise LDO.

If the TVDAC output is not used VDAC can be connected to 3V3, but it must be powered even if the

TV-out functionality is unused.

10

Thermals

The BCM283x SoC employs DVFS (Dynamic Voltage and Frequency Scaling) on the core voltage.

When the processor is idle (low CPU utilisation), it will reduce the core frequency and voltage to reduce

current draw and heat output. When the core utilisation exceeds a certain threshold the core votlage

is increased and the core frequency is boosted to the maximum working frerquency. The voltage and

frequency are throttled back when the CPU load reduces back to an ’idle’ level OR when the silicon

temperature as mesured by the on-chip temperature sensor exceeds 85C (thermal throttling).

A designer must pay careful attention to the thermal design of products using the CM3/CM3L so that

performance is not artificially curtailed due to the processor thermal throttling, as the Quad ARM com-

plex in the BCM2837 can generate significant heat output.

10.1

Temperature Range

The operating temperature range of the module is set by the lowest maximum and highest minimum of

any of the components used.

The eMMC and LPDDR2 have the narrowest range, these are rated for -25 to +80 degrees Celsius.

Therefore the nominal range for the CM3 and CM3L is -25C to +80C.

However, this range is the maximum for the silicon die; therefore, users would have to take into account

the heat generated when in use and make sure this does not cause the temperature to exceed 80 degrees

Celsius.

11

Availability

Raspberry Pi guarantee availability of CM1, CM3 and CM3 Lite until at least January 2023.

12

Support

For support please see the hardware documentation section of the Raspberry Pi website and post ques-

tions to the Raspberry Pi forum.

21

Version 1.0