MAX4937CTN+ Maxim Integrated Products, MAX4937CTN+ Datasheet - Page 16

• Manufacturer Part Number: MAX4937CTN+
• Description: Multiplexer Switch ICs OCTAL HV T/R SWITCH Octal HV T/R Switch
• Manufacturer: Maxim Integrated Products

Specifications of MAX4937CTN+

• Number Of Channels: 8 Channel
• On Time (max): 200 ns
• Off Time (max): 100 ns
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 1.62 V
• Supply Current: 1.5 mA
• Maximum Power Dissipation: 3279 mW
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: 0 C
• Package / Case: TQFN-56
• Mounting Style: SMD/SMT
• Off Isolation (typ): - 50 dB
• Off State Leakage Current (max): 3 uA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 5. Ultrasound T/R Path with One Transmit per Receive Channel (One Channel Only)
Octal High-Voltage Transmit/Receive Switches
For medical ultrasound applications, see Figures 5, 6,
and 7.
Unlike typical communications applications, the two input
tones are not equal in magnitude for the ultrasound-spe-
cific IMD3 two-tone specification. In this measurement,
F1 represents reflections from tissue and F2 represents
reflections from blood. The latter reflections are typically
25dB lower in magnitude, and hence the measurement
is defined with one input tone 25dB lower than the other.
The IMD3 product of interest (F1 - (F2 - F1)) presents
itself as an undesired Doppler error signal in ultrasound
applications. See Figure 8.
The digital interface inputs CLK, DIN, LE, and CLR are
tolerant of up to +5.5V, independent of the V
voltage, allowing compatibility with higher voltage con-
trollers.
Digital output DOUT is provided to allow the connec-
tion of multiple devices by daisy-chaining (Figure 9).
Connect each DOUT to the DIN of the subsequent
device in the chain. Connect CLK, LE, and CLR inputs of
16
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Ultrasound-Specific IMD3 Specification
Daisy-Chaining Multiple Devices
Applications Information
TRANSDUCERS
MUX
MUX
MUX
HV
HV
HV
CONNECTORS
Logic Levels
RELAY
MUX
DD
supply
CONTROL
SPI
all devices, and drive LE logic-low to update all devices
simultaneously. Drive CLR high to open all the switches
simultaneously. Additional shift registers can be includ-
ed anywhere in series with the device data chain.
The devices do not require special sequencing of the
V
switch inputs must be unconnected, or satisfy V
(V
down. Bypass V
ceramic capacitor as close as possible to the device.
The pin configuration is optimized to facilitate a very
compact physical layout of the device and its associated
discrete components. A typical application for this device
might incorporate several devices in close proximity to
handle multiple channels of signal processing.
The exposed pad (EP) of the TQFN-EP package provides
a low thermal resistance path to the die. It is important that
the PCB on which the device is mounted be designed to
conduct heat from the EP. In addition, provide the EP with
a low-inductance path to electrical ground. The EP must
be soldered to a ground plane on the PCB, either directly
or through an array of plated through holes.
DD
HV_
COM_
CLK
DIN
DOUT
CLR
LE
, V
, V
CC,
COM_
MAX4936/MAX4938
GND
+3V
V
DD
and V
Supply Sequencing and Bypassing
, V
NO_
DD
EE
+5V
V
V
-5V
CC
EE
, V
) P V
Application Diagrams
supply voltages; however, analog
CC
NO_
HV_
CC
, and V
during power up and power
XMT
RCV
EE
to GND with a 1FF
PCB Layout
EE
P