 The
two new devices of the HC family are digitally controlled analog
switches, designed in advanced silicon-gate CMOS technology, they are similar to the 4051/2 series, however feature injection current
effect control family. This makes them suited to use in automotive
applications where voltages in excess of the normal logic voltage
are common. The injection current effect control allows signals
at disabled input channels to exceed the supply voltage range or
to go below ground without affecting the signal of the enabled analog
channel. This eliminates the need for external diode-resistor networks
typically used to keep the analog channel signals within the supply
voltage range. These switches have low “on” resistance
and low “off” leakages. They are bidirectional switches,
thus any analog input may be used as an output and vice-versa. Also
these devices contain linearization circuitry which lowers the on-resistance
and increases switch linearity.
| Injection Current Mechanism |
 The
M74HC4851 connects together the outputs of 8 switches, thus achieving
an 8 channel multiplexer.
On the other hand, the M74HC4852 connects the outputs of 4 switches
in two sets, achieving a pair of 4 channel multiplexers.
Both devices also have an inhibit control which when HIGH will disable
all switches to their off state.
| P / N |
SO |
SO IN REEL |
TSSOP in
reel |
| M74HC4851 |
M1R |
RM13TR |
TTR |
| M74HC4852 |
M1R |
RM13TR |
TTR |
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Fast switching: tPD = 8.6ns (typ.) at TA =25°C,
Vcc=4.5V
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Injection current cross coupling (protection)
less than 1mV/mA
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Pin and function compatible with M74HC405X
devices
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Low power dissipation: Icc= 2mA (Max.) at TA=25°C
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Wide operating supply voltage range: Vcc=2V
to 6V
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Available in SO-16 and TSSOP16 packages
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Very low “ON” resistance at TA= 25°C:
215Ohm (typ.) at Vcc=3.0V
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