MAX9656AEP+T Maxim Integrated Products, MAX9656AEP+T Datasheet - Page 8

• Manufacturer Part Number: MAX9656AEP+T
• Description: IC VIDEO SWIT DUAL SCART 20QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX9656AEP+T

• Function: Video Switch
• Circuit: 2 x SCART
• Voltage Supply Source: Single Supply
• Voltage - Supply, Single/dual (±): 2.7 V ~ 3.6 V
• Current - Supply: 21mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Low-Power Video Switches
for Dual SCART Connectors
The incoming video signals can have any DC bias
because the input sync-tip clamps restore the
DC level. The output amplifiers have a gain of 2V/V.
The MAX9655/MAX9656 operate from a single 3.3V
supply and consume low quiescent power and low
average power. In addition, the MAX9656 also has
shutdown mode.
TV_SEL controls whether the encoder or VCR video sig-
nals are sent to the TV SCART. See Table 1.
On the MAX9656, VCR_SEL controls whether the CVBS
signal from the TV SCART or the encoder is sent to the
VCR SCART. SHDN controls whether the device is on
or off. See Tables 2 and 3. In shutdown, the outputs of
the MAX9656 are high impedance.
Every video signal must be AC-coupled to the
MAX9655/MAX9656 through 0.1µF capacitors. The
MAX9655/MAX9656 have sync-tip clamps and bias cir-
cuits to restore the DC level of the video signal after the
input coupling capacitor. When a video input is select-
ed, the input has a sync-tip clamp, which accepts
video signals that have sync pulses or that reach their
minimum level during sync. Composite video with
blanking and sync (CVBS) is an example of a video sig-
nal with sync pulses. The red, green, and blue signals
in an RGBS signal set are examples of signals that
return to their blank level during sync. The sync-tip volt-
age is internally set to 300mV.
When a video input is not selected, the inputs to the
MAX9655 and the MAX9656 do not distort the video
signal in case the video source is driving video signals
to another video circuit such as a video multiplexer.
The inputs are biased at V
above ground so that the ESD diodes never forward
bias as the video signal changes. The input resistance
Table 4. MAX9655 Input Circuit of Input as Determined by State of TV_SEL
8
_______________________________________________________________________________________
ENC_CVBS_IN
VCR_CVBS_IN
ENC_G_IN
VCR_G_IN
ENC_B_IN
ENC_R_IN
VCR_B_IN
VCR_R_IN
INPUT
DD
/3, which is sufficiently
Operating Modes
(TV_SEL = LOW)
INPUT CIRCUIT
Sync-tip clamp
Sync-tip clamp
Sync-tip clamp
Sync-tip clamp
Input
Bias
Bias
Bias
Bias
is 220kΩ, which presents negligible loading on the
video current DAC. The sole exception to this condition
is ENC_CVBS_IN (MAX9655), in which the input circuit
is always a sync-tip clamp. Table 4 summarizes which
input circuit is active on the inputs of the MAX9655
depending on TV_SEL. Table 5 summarizes which input
circuit is active on the inputs of the MAX9656 depend-
ing on TV_SEL and VCR_SEL.
Table 1. TV_SEL Logic (Applicable to
Both the MAX9655 and the MAX9656)
Table 2. VCR_SEL Logic (Only Applicable
to the MAX9656)
Table 3. SHDN Logic (Only Applicable to
the MAX9656)
LOGIC STATE
LOGIC STATE
High
High
Low
Low
LOGIC STATE
High
Low
Encoder video signals are routed to the
TV SCART.
VCR SCART video signals are routed to
the TV SCART.
CVBS signal from encoder is routed to the
VCR SCART.
CVBS signal from the TV SCART is routed
to the VCR SCART.
(TV_SEL = HIGH)
INPUT CIRCUIT
Sync-tip clamp
Sync-tip clamp
Sync-tip clamp
Sync-tip clamp
Sync-tip clamp
Bias
Bias
Bias
MODE
MODE
MODE
Off
On