1145IB データシートの表示（PDF） - Renesas Electronics
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1145IB
Renesas Electronics
1145IB Datasheet PDF : 13 Pages
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HFA1145
Electrical Specifications
PARAMETER
VSUPPLY = 5V, AV = +1, RF = 510, RL = 100 Unless Otherwise Specified (Continued)
TEST CONDITIONS
(NOTE 3)
TEST
LEVEL TEMP. (°C) MIN
TYP MAX
UNITS
DISABLE Input Logic High Current
Output Disable Time (Note 6)
Output Enable Time (Note 6)
Disabled Output Capacitance
Disabled Output Leakage
Off Isolation
(VDISABLE = 0V, VIN = 1VP-P, Note 6)
VDISABLE = 5V
A
Full
-
1
15
A
VIN =1V,
VDISABLE = 2.4V to 0V
B
25
-
35
-
ns
VIN =1V,
VDISABLE = 0V to 2.4V
B
25
-
180
-
ns
VDISABLE = 0V
B
25
-
2.5
-
pF
VDISABLE = 0V, VIN = 2V,
A
Full
-
3
10
A
VOUT =3V
At 5MHz
B
25
-
-75
-
dB
At 25MHz
B
25
-
-60
-
dB
POWER SUPPLY CHARACTERISTICS
Power Supply Range
C
25
4.5
-
5.5
V
Power Supply Current (Note 6)
A
25
-
5.8
6.1
mA
A
Full
-
5.9
6.3
mA
NOTES:
3. Test Level: A. Production Tested; B. Typical or Guaranteed Limit Based on Characterization; C. Design Typical for Information Only.
4. Undershoot dominates for output signal swings below GND (e.g. 0.5VP-P), yielding a higher overshoot limit compared to the VOUT = 0 to 0.5V
condition. See the “Application Information” section for details.
5. Slew rates are asymmetrical if the output swings below GND (e.g. a bipolar signal). Positive unipolar output signals have symmetric positive and
negative slew rates comparable to the +SR specification. See the “Application Information” section, and the pulse response graphs for details.
6. See Typical Performance Curves for more information.
Application Information
Optimum Feedback Resistor
Although a current feedback amplifier’s bandwidth
dependency on closed loop gain isn’t as severe as that of a
voltage feedback amplifier, there can be an appreciable
decrease in bandwidth at higher gains. This decrease may be
minimized by taking advantage of the current feedback
amplifier’s unique relationship between bandwidth and RF. All
current feedback amplifiers require a feedback resistor, even
for unity gain applications, and RF, in conjunction with the
internal compensation capacitor, sets the dominant pole of the
frequency response. Thus, the amplifier’s bandwidth is
inversely proportional to RF. The HFA1145 design is optimized
for RF = 510 at a gain of +2. Decreasing RF decreases
stability, resulting in excessive peaking and overshoot (Note:
Capacitive feedback will cause the same problems due to the
feedback impedance decrease at higher frequencies). At
higher gains, however, the amplifier is more stable so RF can
be decreased in a trade-off of stability for bandwidth.
The table below lists recommended RF values for various
gains, and the expected bandwidth. For a gain of +1, a
resistor (+RS) in series with +IN is required to reduce gain
peaking and increase stability.
GAIN
(ACL)
-1
+1
+2
+5
+10
RF ()
425
510 (+RS = 510)
510
200
180
BANDWIDTH
(MHz)
300
270
330
300
130
Non-inverting Input Source Impedance
For best operation, the DC source impedance seen by the
non-inverting input should be 50This is especially
important in inverting gain configurations where the non-
inverting input would normally be connected directly to GND.
DISABLE Input TTL Compatibility
The HFA1145 derives an internal GND reference for the
digital circuitry as long as the power supplies are
symmetrical about GND. With symmetrical supplies the
digital switching threshold (VTH = (VIH + VIL)/2 = (2.0 +
0.8)/2) is 1.4V, which ensures the TTL compatibility of the
DISABLE input. If asymmetrical supplies (e.g. +10V, 0V) are
utilized, the switching threshold becomes:
VTH = V-----+----2-+----V------ + 1.4V
and the VIH and VIL levels will be VTH 0.6V, respectively.
FN3955 Rev 5.00
July 15, 2015
Page 5 of 13
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