Datasheet

MAX4968/MAX4968A
16-Channel, Linear, High-Voltage
Analog Switches
10
Bleed Resistors (MAX4968A)
The MAX4968A features integrated 40kI (typ) bleed
resistors to discharge capacitive loads such as piezo-
electric transducers. Each analog switch terminal is con-
nected to GND with a bleed resistor.
Serial Interface
The MAX4968/MAX4968A are controlled by a serial
interface with a 16-bit serial shift register and transparent
latch. Each of the 16 data bits controls a single analog
switch (see Table 1). Data on DIN is clocked with the
most significant bit (MSB) first into the shift register on
the rising edge of CLK. Data is clocked out of the shift
register onto DOUT on the rising edge of CLK. DOUT
reflects the status of DIN, delayed by 16 clock cycles
(see Figures 2 and 3).
Latch Enable (LE)
Drive LE logic-low to change the contents of the latch
and update the state of the high-voltage switches
(Figure 3). Drive LE logic-high to freeze the contents of
the latch and prevent changes to the switch states. To
reduce noise due to clock feedthrough, drive LE logic-
high while data is clocked into the shift register. After
the data shift register is loaded with valid data, pulse
LE logic-low to load the contents of the shift register into
the latch.
Latch Clear (CLR)
The MAX4968/MAX4968A feature a latch-clear input.
Drive CLR logic-high to reset the contents of the latch
to zero and open all switches. CLR does not affect the
contents of the data shift register. Pulse LE logic-low to
reload the contents of the shift register into the latch.
Power-On Reset
The MAX4968/MAX4968A feature a power-on-reset cir-
cuit to ensure all switches are open at power-on. The
internal 16-bit serial shift register and latch are set to
zero on power-up.
Table 1. Serial Interface Programming (Notes 1–6)
DATA BITS
CONTROL
BITS
FUNCTION
D0
(LSB)
D1 D2 D3 D4 D5 D6 D7
LE
CLR SW0 SW1 SW2 SW3 SW4 SW5 SW6 SW7
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