HDMI2C1-14HD Datasheet, PDF (11/32 Pages) STMicroelectronics – HPD pull down and signal conditioning

HDMI2C1-14HD
Application information
2.4
+5V protection and fault line functional block description
The +5 V power supply that the source device has to provide to the HDMI^™ cable is
described by the HDMI^™ 2.0 standard. It must be protected against accidental short circuit
that could occur on the cable side.
The HDMI2C1-14HD device embeds a low drop current limiter. If an over-current is
detected, the HDMI2C1-14HD limits the current through the +5 V power supply.If the current
is too high (short circuit), the device opens the +5 V.
Furthermore, the HDMI2C1-14HD device embeds also an over temperature protection
(OTP). If the internal temperature of the device reaches a too high value, the +5 V supply is
opened in order to protect the application.
In case either the current limiter or the OTP is triggered, the fault pin switches down to low
state level (open drain topology) in order to optionally inform the HDMI^™ ASIC that an
abnormal situation has been detected (option).
An under voltage lockout (UVLO) is also integrated in the block. It checks the main +5 V
power supply state, and enables the 5V_OUT only if the main power supply has reached a
minimal value V_{DD_5V_ON}.
The Figure 10 shows the functional diagram of the current limiter block.
VDD_IC
HDMI
ASIC
or
IC
Figure 10. +5 V functional diagram
5V
VDD_5V
RPU_FAULT
FAULT
Current
sensor
UVLO
Low drop current limiter
OTP
Ctrl
+5V_OUT
HDMI
connector
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
17
16
19
18
To summarize, the short circuit protection and the over temperature protection features are
providing a high robustness level of the application. On top of this, the fault line can be used
in order to improve the user experience.
The 5V_OUT pin integrates a protection against ESD which is compliant with IEC61000-4-2
standard, level 4 (8 kV contact). The decoupling capacitance is mandatory, according to the
power management state of the art.
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