ISL21440 Datasheet, PDF (13/15 Pages) Intersil Corporation – Micropower Voltage Reference with Comparator

ISL21440
Window Comparator
The ISL21440 can be combined with a micropower to
produce a window comparator circuit. The circuit in
Figure 25 uses a 3 resistor divider to produce high and
low trip points, and the ISL28197 (800nA supply current)
comparator is added to give the second output. The two
outputs can be used separately for over or undervoltage
indication, or a gate can be added as shown to report
either in-window or out-of window condition.
The resistors are shown as Equations 3, 4 and 5 as
follows.
Set:
R₃ = 1M(1%)
R₂ = R₃[V_H ⁄ V_L – 1]
(EQ. 3)
(EQ. 4)
R₁ = R₃([V_H ⁄ V_REF – 1] – R₂)
(EQ. 5)
Example: For V_H = 3.8V, V_L = 2.7V (3.3V ± 0.5V)
R₂ = 402k, R₁ = 1.82M (can be 1%)
The resulting circuit draws about 3µA and works down to
V_DD = 2.2V.
V_BAT
V_BAT OR V_DD
R1
V+
IN+
+
OUT
VLOW-
IN- _-
V_WINDOW
HYST
R2
REF ^ISL21440
VHI-
V- GND
+
-
ISL28197
R3
FIGURE 25. WINDOW COMPARATOR CIRCUIT
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to
web to make sure you have the latest Rev.
DATE
REVISION
CHANGE
3/2/10
FN6532.1
Updated datasheet with the TDFN spec.
Spec added on pages 5-6 are: VOS, IIN, CMRR and PSRR. Each spec has an added row for the
TDFN package and the original limit for the MSOP package.
12/7/09
FN6532.0 Initial Release
Products
Intersil Corporation is a leader in the design and manufacture of high-performance analog semiconductors. The
Company's products address some of the industry's fastest growing markets, such as, flat panel displays, cell phones,
handheld products, and notebooks. Intersil's product families address power management and analog signal
processing functions. Go to www.intersil.com/products for a complete list of Intersil product families.
*For a complete listing of Applications, Related Documentation and Related Parts, please see the respective device
information page on intersil.com: ISL21440
To report errors or suggestions for this datasheet, please go to www.intersil.com/askourstaff
FITs are available from our website at http://rel.intersil.com/reports/search.php
13
FN6532.1
March 2, 2010