Datasheet

MAX4638/MAX4639
3.5
Ω , Single 8:1 and Dual 4:1,
Low-Voltage Analog Multiplexers
9
Maxim Integrated
Detailed Description
The MAX4638/MAX4639 are low-voltage, CMOS analog
muxes. The MAX4638 is an 8:1 mux that switches one
of eight inputs (NO1–NO8) to a common output (COM)
as determined by the 3-bit binary inputs A0, A1, and
A2. The MAX4639 is a 4:1 dual mux that switches one
of four differential inputs to a common differential out-
put as determined by the 2-bit binary inputs A0 and A1.
Both the MAX4638/MAX4639 have an EN input that can
be used to enable or disable the device. When dis-
abled, all channels are switched off. See Truth Tables.
Applications Information
Overvoltage Protection
Proper power-supply sequencing is recommended for
all CMOS devices. Do not exceed the absolute maxi-
mum ratings because stresses beyond the listed rat-
ings can cause permanent damage to the devices.
Always sequence V+ on first, then V-, followed by the
logic inputs. If power-supply sequencing is not possi-
ble, add two small-signal diodes (D1, D2) in series with
the supply pins for overvoltage protection (Figure 1).
Adding diodes reduces the analog signal range to one
diode drop below V+ and one diode drop above V-, but
does not affect the devices’ low switch resistance.
Device operation is unchanged, and the difference
between V+ and V- should not exceed 6V. These pro-
tection diodes are not recommended when using a sin-
gle supply. For single-supply operation, V- should be
connected to GND as close to the device as possible.
COM_
V-
V+
NO_
* INTERNAL PROTECTION DIODES
D2
D1
-2.5V
+2.5V
MAX4638
MAX4639
*
*
*
*
Figure 1. Overvoltage Protection Using External Blocking
Diodes
A2 A1 A0 EN ON SWITCH
X X X 0 None
0 0 0 1 NO1
0 0 1 1 NO2
0 1 0 1 NO3
0 1 1 1 NO4
1 0 0 1 NO5
1 0 1 1 NO6
1 1 0 1 NO7
1 1 1 1 NO8
A1 A0 EN COMA COMB
X X 0 None None
0 0 1 NO1A NO1B
0 1 1 NO2A NO2B
1 0 1 NO3A NO3B
1 1 1 NO4A NO4B
MAX4638 (Single 8-to-1 Mux) MAX4639 (Dual 4-to-1 Mux)
Truth Tables