NEC startWARE-GHS-Ravin-E, User Manual

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Chapter 3 Functional Description
User’s Manual U17316EE1V0UM00
The startWARE-GHS-Ravin-E board provides two display outputs, each of which conveys the same dis-
play c
ontents. 75 Ω RGB video drivers are provided on board, so that a 0.7
V
PP
monitor can be directly
connected to CN12. 5 V TTL compatible sync signals are provided as well on this connector. The dot
clock can optionally be enabled on this connector via jumper JP4. Note that this connection is not
required for standard VGA monitors and it might even cause problems. Therefore JP4 is normally
unconnected. Check your monitor specification before setting JP4. JP4 may be useful when connecting
an analog TFT display to this connector.
CN13 connects to a digital display, usually a TFT. Along with the digital colour, CN13 provides the sync
and the dot clock signals, as well as a few control signals for the TFT display. JP3 switches the interface
voltage between 3.3 V LVTTL and 5.0 V TTL. CN13 also provides the 5 V and 3.3 V operating voltages.
See the chapter on power consumption below for details on the current ratings.
Three LEDs are provided to quickly check the operating voltages. D1 connects to the externally
supplied 5 V, D2 to the 3.3 V and D3 to the 2.5 V. The 3.3 V and the 2.5 V are locally generated on the
startWARE-GHS-Ravin-E board. When power is supplied, then all these LEDs should light up with
about the same intensity.
CN14 is a connector for JTAG boundary scan equipment. The SAF7113H is the first device in the scan
chain, while Ravin-E is the second one.
3.1 Power Consumption
The startWARE-GHS-Ravin-E board is supplied with a 5 V DC operating voltage from the main
board. The internally required 3.3 V and 2.5 V are generated by linear voltage regulators on the
Ravin-E board. The following table shows the operating currents that have been measured under typi-
cal operating conditions (capturing video input and displaying it along with graphics). Note that these
are reference values of just one board and that other boards may show slightly different current con-
sumption, even if the conditions are the same.
Notes: 1. Estimated, not measured (includes current for V
CC
3.3, V
CC
2.5 and AV
DD2
)
2. Do not permanently exceed these limits (e.g. by external loads)
The measured values include the power consumption of the respective voltage regulator, which is neg-
ligible. The voltage regulators have shunt resistors at their input voltage pin. These resistors can serve
well for current consumption measurements, but their other purpose is to burn away some of the power,
so that only part of it is dissipated in the regulator itself.
The V
CC
3.3 voltage regulator (IC8) along with its shunt resistors and its heat sink on the PCB is
designed to source up to 400 mA. Therefore it can supply external circuits (e.g. a suitable TFT Display)
as long as they do not draw more than about 250 mA. Take care not to couple external noise onto this
supply rail.
Table 3-1: Operating Currents under typical operating conditions
Voltage Measured current
Design limit
Note 2
5 V
500 mA
Note 1
1000 mA
V
CC
3.3
160 mA 400 mA
V
CC
2.5
230 mA 300 mA
AV
DD2
36 mA 100 mA