BUF04701

8

SBOS214B

www.ti.com

FIGURE 3. Limiting Input Current on the BUF04701.

FIGURE 4. BUF04701—No Phase Inversion with Inputs

Greater than the Power-Supply Voltage.

1/4

BUF04701

V+

V–

V

IN

V

OUT

R

S

V

S = ±6V, VIN = 13Vp-p, G = +1

20

µs/div

APPLICATIONS INFORMATION

Figure 1 shows the BUF04701 connected as a buffer. Power

supplies should be bypassed with capacitors connected

close to the device pins. Capacitor values as low as 0.1

µF

will assure stable operation in most applications, but high

output current and fast output slewing can demand large

current transients from the power supplies.

Rail-to-rail input and output swing helps maintain dynamic

range, especially in low supply applications. Figure 2 shows

the input and output waveforms for the BUF04701. On a

±6V

supply with a 100k

Ω load connected to V

S/2, the output is

tested to swing within 50mV to the rail.

OPERATING VOLTAGE

The BUF04701 is fully specified and tested from 3.5V to 12V

over a temperature range of –40

°C to +125°C. Parameters

that vary significantly with operating voltages or temperature

are shown in the Typical Characteristic Curves.

RAIL-TO-RAIL INPUT

The input common-mode voltage range of the BUF04701

extends 100mV beyond the supply rails at room temperature;

however, due to the fixed gain at G = 1, the output will

limit the useable input range. This wide swing is achieved

with a complementary input stage—an N-channel input

differential pair in parallel with a P-channel differential pair.

The N-channel pair is active for input voltages close to the

positive rail, typically (V+) – 2.0V to 100mV above the

positive supply, while the P-channel pair is on for inputs

from 100mV below the negative supply to approximately

(V+) – 1.5V. There is a small transition region, typically

(V+) – 2.0V to (V+) – 1.5V, in which both pairs are on. This

500mV transition region can vary

±100mV with process

variation. Thus, the transition region (both stages on) can

range from (V+) – 2.1V to (V+) – 1.4V on the low end, up to

(V+) – 1.9V to (V+) – 1.6V on the high end.

INPUT PROTECTION

Device inputs are protected by ESD diodes that will conduct

if the input voltages exceed the power supplies by more than

approximately 300mV. Momentary voltages greater than

300mV beyond the power supply can be tolerated if the

current is limited to 10mA. This is easily accomplished with

an input resistor, in series with the buffer input shown in

Figure 3. Many input signals are inherently current-limited to

less than 10mA; therefore, a limiting resistor is not always

required. The BUF04701 features no phase inversion when

the inputs extend beyond supplies if the input current is

limited, as shown in Figure 4.

FIGURE 1. Basic Connections.

FIGURE 2. Rail-to-Rail Input and Output.

1/4

BUF04701

V+

V–

V

IN

R

L

0.1

µF

0.1

µF

Input

G = +1, V

S ± 6V

Output (Inverted on oscilloscope)

20

µs/div

8

6

4

2

0

–2

–4

–6

–8