Datasheet

0 4 8 12 16 20 24
200
3000
SLEW RATE (V/Ps)
INPUT AMPLITUDE (V
PP
)
600
1000
1400
1800
2200
2600
V
S
= ±15V
R
L
= 1 k:
R
L
= 50:
LMH6321
GND
V
+
V
-
V
+
OP AMP
R
1
R
2
-
+
LMH6321
SNOSAL8C –APRIL 2006–REVISED MARCH 2013 www.ti.com
Figure 56. Using an Op Amp to Bias the GND Pin to ½ V
+
for Single Supply Operation
In Figure 56, the op amp circuit pre-biases the GND pin of the buffer for single supply operation.
The GND pin can be driven by an op amp configured as a constant voltage source, with the output voltage set by
the resistor voltage divider, R
1
and R
2
. It is recommended that These resistors be chosen so as to set the GND
pin to V
+
/2, for maximum common mode range.
SLEW RATE
Slew rate is the rate of change of output voltage for large-signal step input changes. For resistive load, slew rate
is limited by internal circuit capacitance and operating current (in general, the higher the operating current for a
given internal capacitance, the faster is the slew rate). Figure 57 shows the slew capabilities of the LMH6321
under large signal input conditions, using a resistive load.
Figure 57. Slew Rate vs. Peak-to-Peak Input Voltage
However, when driving capacitive loads, the slew rate may be limited by the available peak output current
according to the following expression.
dv/dt = I
PK
/C
L
(10)
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