Datasheet

MAX4968/MAX4968A
16-Channel, Linear, High-Voltage
Analog Switches
11
Table 1. Serial Interface Programming (Notes 1–6) (continued)
Note 1: The 16 switches operate independently.
Note 2: Serial data is clocked in on the rising edge of CLK.
Note 3: The switches go to a state retaining their present condition on the rising edge of LE. When LE is low, the shift register data
flows through the latch.
Note 4: DOUT is high when switch 15 is on.
Note 5: Shift register clocking has no effect on the switch states if LE is high.
Note 6: The CLR input overrides all other inputs.
Applications Information
In typical ultrasound applications, the MAX4968/MAX4968A
do not require dedicated high-voltage supplies; the nega-
tive voltage supply can be shared with the transmitter and
the positive voltage supply is typically +10V. See Figures 5,
6, and 7 for medical ultrasound applications.
Logic Levels
The MAX4968/MAX4968A digital interface inputs CLK,
DIN, LE, and CLR operate on the V
DD
logic supply voltage.
Daisy-Chaining Multiple Devices
Digital output DOUT is provided to allow the connec-
tion of multiple MAX4968/MAX4968A devices by daisy-
chaining (Figure 4). Connect each DOUT to the DIN of
the subsequent device in the chain. Connect CLK, LE,
and CLR inputs of 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 included anywhere in series with the
MAX4968/MAX4968A daisy-chain.
Supply Sequencing and Bypassing
The MAX4968/MAX4968A do not require special
sequencing of the V
DD
, V
PP,
and V
NN
supply voltages.
Bypass V
DD
, V
PP
, and V
NN
to GND with a 0.1FF ceramic
capacitor as close as possible to the device.
Note: Keep LE low during power-up.
DATA BITS
CONTROL
BITS
FUNCTION
D8 D9 D10 D11 D12 D13 D14
D15
(MSB)
LE
CLR SW8 SW9 SW10 SW11 SW12 SW13 SW14 SW15
L L L Off
H L L On
L L L Off
H L L On
L L L Off
H L L On
L L L Off
H L L On
L L L Off
H L L On
L L L Off
H L L On
L L L Off
H L L On
L L L Off
H L L On
X X X X X X X X H L Hold Previous State
X X X X X X X X X H Off Off Off Off Off Off Off Off