BUF16821-Q1 Datasheet, PDF (18/38 Pages) Texas Instruments – Programmable Gamma-Voltage Generator

BUF16821-Q1
SBOS712 – MAY 2014
www.ti.com
7.3.8 Output Protection
The device output stages can safely source and sink the current levels indicated in Figure 2 and Figure 3.
However, there are other modes where precautions must be taken to prevent the output stages from being
damaged by excessive current flow. The outputs (OUT1 through OUT16, VCOM1 and VCOM2) include
electrostatic discharge (ESD) protection diodes, as shown in Figure 17. Normally, these diodes do not conduct
and are passive during typical device operation. Unusual operating conditions can occur where the diodes may
conduct, potentially subjecting them to high, even damaging current levels. These conditions are most likely to
occur when a voltage applied to an output exceeds (V_S) + 0.5 V, or drops below GND – 0.5 V.
One common scenario where this condition can occur is when the output pin is connected to a sufficiently large
capacitor and the device power-supply source (V_S) is suddenly removed. Removing the power-supply source
allows the capacitor to discharge through the current-steering diodes. The energy released during the high
current flow period causes the power dissipation limits of the diode to be exceeded. Protection against the high
current flow may be provided by placing current-limiting resistors in series with the output; see Figure 19. Select
a resistor value that restricts the current level to the maximum rating for the particular pin.
V_S
Device
ESD Current-Steering
Diodes
OUTx or VCOMx
Figure 17. Output Pins ESD Protection Current-Steering Diodes
18
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