Datasheet

MAX4968/MAX4968A
16-Channel, Linear, High-Voltage
Analog Switches
9
Detailed Description
The MAX4968/MAX4968A are 16-channel, high-linearity,
high-voltage, bidirectional SPST analog switches with
18I (typ) on-resistance. The devices are ideal for use in
applications requiring high-voltage switching controlled
by a low-voltage control signal, such as ultrasound imag-
ing and printers. The MAX4968A provides integrated
40kI (typ) bleed resistors on each switch terminal to
discharge capacitive loads. Using HVCMOS technol-
ogy, these switches combine high-voltage, bilateral MOS
switches and low-power CMOS logic to provide efficient
control of high-voltage analog signals.
The MAX4968 is pin-to-pin compatible with the MAX14802
and Supertex HV2601. The MAX4968A is pin-to-pin
compatible with the MAX14803 and Supertex HV2701.
The only difference is the V
PP
positive supply voltage
level. The MAX4968/MAX4968A require a low +10V (typ)
voltage (V
PP
), whereas the MAX14802/MAX14803 and
HV2601/HV2701 require a high +100V supply voltage.
In typical ultrasound applications, these devices do not
require dedicated high-voltage supply, which implies
a significant simplification of system requirement. The
negative voltage supply can be shared with the transmit-
ter and the positive voltage supply is typically +10V.
Analog Switch
The devices can transmit analog signals up to 210V
P-P
,
with an analog signal range from V
NN
to V
NN
+ 210V.
Before starting the high-voltage burst transmission (V
P-P
> +20V), the input voltage is required to be close to
GND to allow a proper settling of the pass FET. The high-
voltage burst frequency must be greater than 500kHz.
Extremely long high-voltage bursts (V
P-P
> +10V) with
duty cycle greater than 20% could result in signal deg-
radation, especially for unipolar transmission. In general,
this applies for burst transmission with a nonzero DC
content.
Low-voltage signal (V
P-P
< 10V) continuous-wave bipo-
lar transmission is supported for frequencies greater
than 500kHz. For very small signals, such as the small
echoes in typical ultrasound imaging systems (V
P-P
<
10V), the devices are not limited to a low-frequency
bandwidth and can transmit DC signals.
Voltage Supplies
The devices operate with a high-voltage supply V
NN
from -160V to 0, V
PP
supply of +10V (typ), and a logic
supply V
DD
(+2.37V to +5.5V).
Pin Description (continued)
PIN NAME FUNCTION
28 SW14A Analog Switch 14—Terminal
29 SW13B Analog Switch 13—Terminal
30 SW13A Analog Switch 13—Terminal
31 SW12B Analog Switch 12—Terminal
32 SW12A Analog Switch 12—Terminal
33 SW11B Analog Switch 11—Terminal
34 SW11A Analog Switch 11—Terminal
37 SW10B Analog Switch 10—Terminal
38 SW10A Analog Switch 10—Terminal
39 SW9B Analog Switch 9—Terminal
PIN NAME FUNCTION
40 SW9A Analog Switch 9—Terminal
41 SW8B Analog Switch 8—Terminal
42 SW8A Analog Switch 8—Terminal
43 SW7B Analog Switch 7—Terminal
44 SW7A Analog Switch 7—Terminal
45 SW6B Analog Switch 6—Terminal
46 SW6A Analog Switch 6—Terminal
47 SW5B Analog Switch 5—Terminal
48 SW5A Analog Switch 5—Terminal