MAX4887 Datasheet, PDF (8/12 Pages) Maxim Integrated Products – Triple Video Switch

Triple Video Switch
MAX4887
SWITCH
INPUT
V_IN
RO, GO, BO
V+
V+
R_, G_, B_
LOGIC
INPUT
SEL
GND
SWITCH
OUTPUT
V_OUT
R_L
C_L
C_L INCLUDES FIXTURE AND STRAY CAPACITANCE.
( ) ^VOUT ^{= V}IN
RL
R_L + R_ON
Figure 2. Switching Time
MAX4887
SWITCH
INPUT ^RGEN
RO, GO, BO
V+
V+
R_, G_, B_
V_GEN
GND
SEL
SWITCH
OUTPUT
VOUT
C_L
LOGIC INPUT (0 TO V+)
Timing Diagrams/Test Circuits
LOGIC ^V+
INPUT _0V
50%
tr < 5ns
tf < 5ns
t_OFF
V_OUT
SWITCH _0V
OUTPUT
0.9 x V_0UT
t_ON
0.9 x V_0UT
LOGIC INPUT WAVEFORMS INVERTED FOR SWITCHES
THAT HAVE THE OPPOSITE LOGIC SENSE.
V_OUT
∆V_OUT
V+
ON
OFF
OFF
SEL 0V
Q = (∆V_OUT)(C_L)
Figure 3. Charge Injection
Charge Pump
A low-noise charge pump with internal capacitors pro-
vides a doubled voltage for driving the RGB analog
switches when operating the MAX4887 at low voltages
(V+ < 5V). The charge pump adds less than 163µV_P-P
of noise to the switches. When operating with V+ = 5V,
the charge pump can be disabled to further reduce
noise; however, the analog switch’s performance is
slightly degraded resulting in higher R_ON and insertion
loss. Drive QP high to disable the charge pump. Drive
QP low for normal operation.
When operating the MAX4887 at 3.3V, connect QP
to GND.
Logic Inputs (EN, SEL)
The MAX4887 has two logic inputs that control the
switch configuration and on/off function. Use SEL to
switch (RGB)₀ to (RGB)₁ or (RGB)₂. Use EN to connect
the switch inputs to the outputs. Drive EN low to enable
the RGB switches inputs/outputs. Drive EN high to
place all inputs/outputs in a high-impedance state.
Table 1 illustrates the MAX4887 truth table.
Table 1. Switch Truth Table
EN
SEL
FUNCTION
0
0
(RGB)₀ to (RGB)₁
0
1
(RGB)₀ to (RGB)₂
1
X
R_, B_, and G_ High Impedance
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