LTC2909CTS8-2.5#PBF Linear Technology, LTC2909CTS8-2.5#PBF Datasheet - Page 9

• Manufacturer Part Number: LTC2909CTS8-2.5#PBF
• Manufacturer: Linear Technology

Specifications of LTC2909CTS8-2.5#PBF

• Voltage Supervisor Type: Voltage Monitor
• Number Of Voltage Supervisors: 3
• Monitored Supervisor Voltage: 3.3
• Operating Supply Voltage (min): 0.5V
• Operating Supply Voltage (max): 6V
• Package Type: TSOT-23
• Operating Temperature Classification: Commercial
• Operating Temp Range: 0C to 70C
• Pin Count: 8
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Compliant

APPLICATIO S I FOR ATIO
If the state of the SEL pin confi gures a given input as
“negative polarity,” the voltage at the ADJx pin must be
below the trip point (0.5V nominal), or the ⎯ R ⎯ S ⎯ T output will
be pulled low. Conversely, if a given input is confi gured
as “positive polarity,” the pin voltage must be above the
trip point or ⎯ R ⎯ S ⎯ T will assert low.
Thus, a “negative polarity” input may be used to determine
whether a monitored negative voltage is smaller in absolute
value than it should be (–UV), or a monitored positive
voltage is larger than it should be (+OV). The opposite is
true for a “positive polarity” input (–OV or +UV). These
usages are also shown in Table 1. For purposes of this
Table 2a. Possible Combinations of Supply Monitoring. For Example Purposes, All Supplies are Monitored at 5% Tolerance and
Connections are Shown Only for ADJ1, ADJ2, REF, SEL
10.2M
3.09M
R
R
3.09M
309k
115k
–15V (OV)
R
R
R
R
115k
N2A
N1A
15V (UV)
1 Positive UV, 1 Negative OV
P2A
P1A
P2
P1
15V (UV)
U
1.15M
1.37M
10.2M
R
R
R
R
137k
118k
309k
2 Negative OV
2 Positive UV
R
R
–15V (OV)
P2B
P1B
N2B
N1B
–5V (OV)
5V (UV)
N2
N1
SEL = V
U
CC
ADJ1
ADJ2
REF
ADJ1
ADJ2
REF
ADJ1
ADJ2
REF
W
SEL
SEL
SEL
U
data sheet, a negative voltage is considered “undervoltage”
if it is closer to ground than it should be (e.g., –4.3V for
a –5V supply).
Proper confi guration of the SEL pin and setting of the
trip-points via external resistors allows for any two fault
conditions to be detected. For example, the LTC2909 may
monitor two supplies (positive, negative or one of each)
for UV or for OV (or one UV and one OV). It may also
monitor a single supply (positive or negative) for both UV
and OV. Tables 2a and 2b show example confi gurations
for monitoring possible combinations of fault condition
and supply polarity.
3.09M
R
R
6.19M
107k
6.19M
–15V (UV)
N2A
N1A
R
R
200k
200k
R
R
1 Positive OV, 1 Negative UV
P2A
P1A
15V (OV)
15V (OV)
P2
P1
1.37M
1.33M
3.09M
R
R
R
R
133k
137k
2 Negative UV
107k
2 Positive OV
N2B
N1B
P2B
P1B
–5V (UV)
–15V (UV)
R
R
5V (OV)
SEL = GND
N2
N1
ADJ1
ADJ2
REF
ADJ1
ADJ2
REF
ADJ1
ADJ2
REF
SEL
SEL
SEL
LTC2909
2909fb
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