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IH5140

High-Level CMOS Analog Switches

Intersil 

IH5140 thru IH5145

Typical Applications

To maximize switching speed on the IH5140 family, TTL open

collector logic (15V with a 1kΩ or less collector resistor)

should be used. This configuration will result in (SPST) tON

and tOFF times of 80ns and 50ns, for signals between -10V

and +10V. The SPDT and DPST switches are approximately

30ns slower in both tON and tOFF with the same drive configu-

ration. 15V CMOS logic levels can be used (0V to +15V), but

propagation delays in the CMOS logic will slow down the

switching (typical 50ns → 100ns delays).

When driving the IH5140 Family from either +5V TTL or

CMOS logic, switching times run 20ns slower than if they

were driven from +15V logic levels. Thus tON is about 105ns,

and tOFF 75ns for SPST switches, and 135ns and 105ns

(tON, tOFF) for SPDT or DPST switches. The low level drive

can be made as fast as the high level drive if ±5V strobe lev-

els are used instead of the usual 0V → +3.0V drive. Pin 13 is

taken to -5V instead of the usual GND and strobe input is

taken from +5V to -5V levels as shown in Figure 11.

ANALOG IN

±15V FROM

DRIVERS

D

D

Q1 B SUBSTRATE Q2

G

S

D

B

G

G

S

±15V FROM

DRIVERS

-15V

Q3

S

“BODY PULLER” FET

ANALOG OUT

FIGURE 12.

Current will flow from -10V analog voltage through the drain

to body junction of Q1, then through the drain to body junc-

tion of Q3 to GND. This means that there is 10V across two

forward-biased silicon diodes and current will go to whatever

value the input signal source is capable of supplying. If the

analog input signal is derived from the same supplies as the

switch this fault condition cannot occur. Turning off the

supplies would turn off the analog signal at the same time.

ANALOG 1

OUT

2

3

4

5

6

7

ANALOG

OUT 8

IH5141

16 ANALOG IN

(CHANNEL A)

15

14 -15V

13 -5V

+5V

12 +5V

11 +15V -5V

10

9 ANALOG IN

(CHANNEL B)

FIGURE 11.

ANALOG IN = -10V

CMOS

LEVEL

INPUT

STROBE

N

Q1 P

Q2

SUBSTRATE

N

N

P

GND WHEN POWER

SUPPLIES ARE OFF

Q3

N

FIGURE 13.

GND WHEN POWER

SUPPLIES ARE OFF

The typical channel of the IH5140 family consists of both

P-Channel and N-channel MOSFETs. The N-channel

MOSFET uses a “Body Puller” FET to drive the body to -15V

(±15V supplies) to get good breakdown voltages when the

switch is in the off state (see Figure 12). This “Body Puller”

FET also allows the N-Channel body to electrically float

when the switch is in the on state producing a fairly constant

rDS(ON) with different signal voltages. While this “Body

Puller” FET improves switch performance, it can cause a

problem when analog input signals are present (negative

signals only) and power supplies are off. This fault condition

is shown in Figure 13.

This fault situation can also be eliminated by placing a diode

in series with the negative supply line (pin 14) as shown in

Figure 14. Now when the power supplies are off and a nega-

tive input signal is present this diode is reverse biased and

no current can flow.

OUTA 1

2

3

4

5

6

7

OUTB 8

IH5141

16 INA

15 T2LAIN

14

13

12 +5V

11 +15V

10 T2LBIN

9 INB

1N914

OR EQUIVALENT

-15V

FIGURE 14.

13-10

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