ISL21440 Datasheet, PDF (11/15 Pages) Intersil Corporation – Micropower Voltage Reference with Comparator

ISL21440
Typical Performance Curves (Continued)
270
245
220
195
170
3V
145
120
95
70
45 _5V
20
10 20 30 40 50 60 70 80 90 100 110 120
INPUT VOLTAGE (mV)
FIGURE 21. OUTPUT RESPONSE TIME vs INPUT
OVERDRIVE (t_PLH)
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
-0.5
0
OUT
V+
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
TIME (ms)
FIGURE 22. POWER-UP/DOWN OUTPUT RESPONSE
(V+ = 5V, IN+ = V+, IN- = V_REF)
3.5
3.0
2.5
2.0
OUT
1.5
V+
1.0
0.5
0
-0.5
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
TIME (ms)
FIGURE 23. POWER-UP/DOWN OUTPUT RESPONSE (V+ = 3V, IN+ = V+, IN- = V_REF)
Functional Description
Device Power
The ISL21440 device has a single positive supply pin, V+,
and two other supply pins, V- and GND. Normally for
single supply applications the V- pin is tied to system
ground as well as the GND pin. The separate ground pin
allows the comparator to be powered by split supplies
from ±1.0V to ±5.5V. Note that the minimum supply
voltage will be 0.8V above the comparator maximum
input level for accurate operation.
Comparator Section
The comparator inputs can swing from the negative
supply (GND pin) to within 0.8V of the positive supply
(V+). Alternatively, with the comparator input set at
the 1.182V reference level, the minimum input voltage
for accurate operation is 2.0V. If the inputs are
expected to see voltage levels above V+ or below
ground, they should be clamped with low leakage
Schottky diodes.
The CMOS output swings essentially from the GND
potential to V+ potential, depending on load current. If
loads in excess of 1mA are expected, then a 0.1µF
decoupling capacitor at the V+ pin should be added.
Voltage Reference Section
The voltage reference is a micropower FGA reference
and is set to 1.182V ±0.5% at the factory. The
reference output can source up to 2mA but the sink
capability is very limited at only 10µA, maximum.
Small value capacitors, up to 10nF, can be used on the
reference output to lower noise if desired.
Applications Information
Handling and Board Mounting
FGA references provide excellent initial accuracy and
low temperature drift at the expense of very little
power drain. There are some precautions to take to
insure this accuracy is not compromised. Excessive
heat during solder reflow can cause excessive initial
accuracy drift, so the recommended +260°C max
11
FN6532.1
March 2, 2010