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ISL28217FBZ-T7 View Datasheet(PDF) - Intersil

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ISL28217FBZ-T7 Datasheet PDF : 25 Pages
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ISL28117, ISL28217
Applications Information
Functional Description
The ISL28117 and ISL28217 are single and dual, low
noise precision op amps. Both devices are fabricated in a
new precision 40V complementary bipolar DI process. A
super-beta NPN input stage with input bias current
cancellation provides low input bias current (180pA
typical), low input offset voltage (13µV typical), low input
noise voltage (8nV/Hz), and low 1/f noise corner
frequency (~8Hz). These amplifiers also feature high
open loop gain (18kV/mV) for excellent CMRR (145dB)
and THD+N performance (0.0005% @ 3.5VRMS, 1kHz
into 2kΩ). A complimentary bipolar output stage enables
high capacitive load drive without external compensation.
Operating Voltage Range
The devices are designed to operate over the 4.5V
(±2.25V) to 40V (±20V) range and are fully
characterized at 10V (±5V) and 30V (±15V). The Power
Supply Rejection Ratio typically exceeds 140dB over the
full operating voltage range and 120dB minimum over
the -40°C to +125°C temperature range. The worst case
common mode input voltage range over temperature is
2V to each rail. With ±15V supplies, CMRR performance
is typically >130dB over-temperature. The minimum
CMRR performance over the -40°C to +125°C
temperature range is >120dB for power supply voltages
from ±5V (10V) to ±15V (30V).
Input Performance
The super-beta NPN input pair provides excellent
frequency response while maintaining high input
precision. High NPN beta (>1000) reduces input bias
current while maintaining good frequency response, low
input bias current and low noise. Input bias cancellation
circuits provide additional bias current reduction to
<1nA, and excellent temperature stabilization. Figures 9
through 16 show the high degree of bias current stability
at ±5V and ±15V supplies that is maintained across the
-40°C to +125°C temperature range. The low bias
current TC also produces very low input offset current
TC, which reduces DC input offset errors in precision,
high impedance amplifiers.
The +25°C maximum input offset voltage (VOS) for the
“B” grade is 50µV and 100µV for the “C” grade. Input
offset voltage temperature coefficients (VOSTC) are a
maximum of ±0.6µV/°C for the “B” and ±0.9µV/°C for the
“C” grade. Figures 1 through 4 show the typical gaussian-
like distribution over the ±5V to ±15V supply range and
over the full temperature range. The VOS temperature
behavior is smooth (Figures 5 through 8) maintaining
constant TC across the entire temperature range.
Input ESD Diode Protection
The input terminals (IN+ and IN-) have internal ESD
protection diodes to the positive and negative supply
rails, series connected 500Ω current limiting resistors
and an anti-parallel diode pair across the inputs
(Figure 51).
VIN
V+
- 500Ω
+ 500Ω
VOUT
RL
V-
FIGURE 51. INPUT ESD DIODE CURRENT LIMITING-
UNITY GAIN
The series resistors limit the high feed-through currents
that can occur in pulse applications when the input
dV/dT exceeds the 0.5V/µs slew rate of the amplifier.
Without the series resistors, the input can forward-bias
the anti-parallel diodes causing current to flow to the
output resulting in severe distortion and possible diode
failure. Figure 46 provides an example of distortion free
large signal response using a 4VP-P input pulse with an
input rise time of <1ns. The series resistors enable the
input differential voltage to be equal to the maximum
power supply voltage (40V) without damage.
In applications where one or both amplifier input
terminals are at risk of exposure to high voltages beyond
the power supply rails, current limiting resistors may be
needed at the input terminal to limit the current through
the power supply ESD diodes to 20mA max.
Output Current Limiting
The output current is internally limited to approximately
±45mA at +25°C and can withstand a short circuit to
either rail as long as the power dissipation limits are not
exceeded. This applies to only 1 amplifier at a time for
the dual op amp. Continuous operation under these
conditions may degrade long term reliability. Figures 25
and 26 show the current limit variation with temperature.
Output Phase Reversal
Output phase reversal is a change of polarity in the
amplifier transfer function when the input voltage
exceeds the supply voltage. The ISL28117 and ISL28217
are immune to output phase reversal, even when the
input voltage is 1V beyond the supplies.
Power Dissipation
It is possible to exceed the +150°C maximum junction
temperatures under certain load and power supply
conditions. It is therefore important to calculate the
maximum junction temperature (TJMAX) for all
applications to determine if power supply voltages, load
conditions, or package type need to be modified to
remain in the safe operating area. These parameters are
related using Equation 1:
TJMAX = TMAX + θJAxPDMAXTOTAL
(EQ. 1)
16
April 13, 2010
FN6632.4
 

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