ICL8211CTY Intersil Corporation, ICL8211CTY Datasheet - Page 9

• Manufacturer Part Number: ICL8211CTY
• Description: Programmable Voltage Detectors
• Manufacturer: Intersil Corporation

almost all the collector current of Q
drive to Q
current of the order of 30mA. It is advisable to externally limit
this current to 25mA or less.
Applications
The ICL8211 and ICL8212 are similar in many respects, espe-
cially with regard to the setup of the input trip conditions and
hysteresis circuitry. The following discussion describes both
devices, and where differences occur they are clearly noted.
General Information
Threshold Input Considerations
Although any voltage between -5V and V+ may be applied to
the THRESHOLD terminal, it is recommended that the
THRESHOLD voltage does not exceed about +6V since
above that voltage the threshold input current increases
sharply. Also, prolonged operation above this voltage will
lead to degradation of device characteristics.
The outputs change states with an input THRESHOLD
voltage of approximately 1.15V. Input and output waveforms
are shown in Figure 21 for a simple 1.15V level detector.
INPUT VOLTAGE
(RECOMMENDED
RANGE -5 TO +5V)
The HYSTERESIS output is a low current output and is
intended primarily for input threshold voltage hysteresis
applications. If this output is used for other applications it is
suggested that output currents be limited to 10 A or less.
The regular OUTPUT’s from either the ICL8211 or ICL8212
may be used to drive most of the common logic families
V
TH
1.15V
V+
0V
V+
0V
0
R
L2
FIGURE 21. VOLTAGE LEVEL DETECTION
21
, resulting in a maximum available collector
1
2
3
4
8
7
6
5
19
is available for base
R
L1
ICL8211 OUTPUT
ICL8212 OUTPUT
V
O2
V+
(V+ MUST BE
EQUAL OR
EXCEED 1.8V)
ICL8211, ICL8212
V
HYST
V
O1
V
O
7-169
such as TTL or CMOS using a single pullup resistor. There is
a guaranteed TTL fanout of 2 for the ICL8211 and 4 for the
ICL8212.
A principal application of the ICL8211 is voltage level
detection, and for that reason the OUTPUT current has been
limited to typically 7mA to permit direct drive of an LED
connected to the positive supply without a series current
limiting resistor.
On the other hand the ICL8212 is intended for applications
such as programmable zener references, and voltage
regulators where output currents well in excess of 7mA are
desirable. Therefore, the output of the ICL8212 is not current
limited, and if the output is used to drive an LED, a series
current limiting resistor must be used.
In most applications an input resistor divider network may be
used to generate the 1.15V required for V
racy, currents as large as 50 A may be used, however for
those applications where current limiting may be desirable,
(such as when operating from a battery) currents as low as
6mA may be considered without a great loss of accuracy.
6mA represents a practical minimum, since it is about this
level where the device’s own input current becomes a signif-
icant percentage of that flowing in the divider network.
Case 1. High accuracy required, current in resistor network
Case 2. Good accuracy required, current in resistor network
V
FIGURE 23. INPUT RESISTOR NETWORK CONSIDERATIONS
TH
INPUT
V-
1
2
3
4
unimportant Set I = 50 A for V
20k
important Set I = 7.5 A for V
150k
FIGURE 22. OUTPUT LOGIC INTERFACE
R
R
2
1
V
TH
8
7
6
5
V+
1
2
3
4
PULLUP RESISTOR
TH
TH
TH
= 1.15V
= 1.15V
. For high accu-
8
7
6
5
CMOS OR
TTL GATES
V+
R
R
1
1