LMH6586_14 Datasheet, PDF (23/34 Pages) Texas Instruments – 32x16 Video Crosspoint Switch

LMH6586
www.ti.com
SNCS105D – JULY 2008 – REVISED MARCH 2013
The maximum power dissipation actually produced by an IC is the total quiescent supply current times the total
power supply voltage, plus the power in the IC due to the load, or:
6 ^PDMAX
=
V_S
x
I_SMAX
+
i
n
=
1
(V_S
±
V_OUTi)
x
V_OUTi
R_Li
where
• V_S = Supply voltage = 5V
• I_SMAX = Maximum quiescent supply current = 300 mA
• V_OUT = Maximum output voltage of the application = 2.6V
• R_L = Load resistance tied to ground = 150Ω
• n = 1 to 16 channels
(2)
Calculating:
P_DMAX = 2.2656
The required θ_JA to dissipate P_DMAX is = (T_JMAX – T_AMAX)/P_DMAX
The table below shows the θ_JA values with airflow and different heatsinks.
LMH6586VS 80-Pin TQFT
LMHXPT
Analog Video Crosspoint Board
NO Heat Sink
Small Tower
x y = 9.57x9.69 mm/ht. 6.28 mm
Aluminum 12 rail
x y = 9.82x10.73 mm/ht.10.07 mm
Anodized 9 rail
x y = 6.10x7.30 mm/ht. 13.67 mm
Round Tower
diameter = 14.35 mm/ht. 4.47 mm
0 LFPM
@ 0.50 watt
0 LFPM
@ 1.0 watt
32.2
30.9
25.5
24.6
25.2
24.1
24.4
23.3
24.2
23.9
0 LFPM 0 LFPM @2.8 225 LFPM @ 500 LFPM @
@ 2.0 watt
watt
2.8 watt
2.8 watt
29.4
28.6
26.8
25.3
23.6
22.9
19.2
15.9
23.0
22.2
16.4
14.2
22.1
21.3
15.6
13.6
22.9
22.4
18.2
15.4
REXT RESISTOR
The REXT external resistor (pin 67) establishes the internal bias current and precise reference voltage for the
LMH6586. For optimal performance, REXT should be a 10 kΩ 1% precision resistor with a low temperature
coefficient to ensure proper operation over a wide temperature range. Using a REXT resistor with less precision
may result in reduced performance against temperature, supply voltage, input signal, or part-to-part variations.
SYNC SEPARATOR OUTPUT
In addition to the 16 video outputs, the LMH6586 has an extra output (V_OUT16) which can select any input
channel. This channel's output buffer only has a gain of 1 since it is not meant to drive a 150Ω video load.
Instead, this video output can be AC coupled to a non-terminated input of an external video sync separator, such
as TI's LMH1980 or LMH1981. The sync separator can extract the synchronization (sync) timing signals, which
can be useful for video triggering or phase-locked loop (PLL) clock generation circuits. Refer to the LMH1980 or
LMH1981 datasheet for more information about these sync separator devices.
I²C INTERFACE
A microcontroller can be used to configure the LMH6586 via the I²C interface. The protocol of the interface
begins with a start pulse followed by a byte comprised of a seven-bit slave device address and a read/write bit as
the LSB. The two lowest bits of the seven-bit slave address are defined by the external connections of inputs
ADDR[1] (pin 72) and ADDR[0] (pin 71), where ADDR[0] is the least significant bit. Because there are four
different combinations of the two ADDR pins, it's possible to have up to four different LMH6586 devices with
unique slave addresses on a common I²C bus. See I²C Device Slave Address Lookup Table.
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