LTC2919HDDB-5#PBF Linear Technology, LTC2919HDDB-5#PBF Datasheet - Page 12

• Manufacturer Part Number: LTC2919HDDB-5#PBF
• Manufacturer: Linear Technology

Specifications of LTC2919HDDB-5#PBF

• Voltage Supervisor Type: Voltage Monitor
• Number Of Voltage Supervisors: 2
• Monitored Supervisor Voltage: 3.3
• Operating Supply Voltage (min): 0.5V
• Operating Temperature Classification: Automotive
• Operating Temp Range: -40C to 125C
• Pin Count: 10
• Mounting: Surface Mount
• Lead Free Status / Rohs Status: Compliant

APPLICATIO S I FOR ATIO
LTC2919
To minimize errors arising from ADJ input bias and to
minimize loading on REF choose resistor R
supply monitoring) or R
in the range of 5k to 100k.
For a positive-monitoring application, R
by:
For a negative-monitoring application:
Note that the value V
application.
The LTC2919 can also be used to monitor a single supply
for both UV and OV. This may be accomplished with three
resistors, instead of the four required for two independent
supplies. Confi gurations are shown in Figures 3 and 4. R
or R
For a given R
For monitoring a negative supply with a given R
12
Figure 3. Setting UV and OV Trip Point for a Positive Supply
R
R
R
R
R
R
P2
N2
N4
P5
P6
N5
N6
V
MON
= R
= R
may be chosen as is R
= R
= R
= R
= R
R
R
R
P6
P5
P4
P1
N1
P4
P4
N4
N4
(2V
(1 – 2V
P4
(
(
V
V
2V
1– 2V
ADJ1
ADJ2
, monitoring a positive supply:
OV
UV
1– V
0.5V
TRIP
UV
V
UV
– V
– V
U
+
–
TRIP
TRIP
UV
– 1)
– 1
UV
UV
OV
N1
+
–
+
–
)
)
)
should be negative for a negative
V
V
1– V
1– V
(for negative supply monitoring)
U
OV
UV
OV
UV
P1
or R
W
MOSFET
MOSFET
LOGIC
DRAIN
LOGIC
DRAIN
OPEN
OPEN
N1
&
&
P2
above.
OUT1
OUT2
P1
is then chosen
2919 F03
(for positive
U
N4
UV
OV
:
P4
For example, consider monitoring a –5V supply at ±10%. For
this supply application: V
Suppose we wish to consume about 5μA in the divider, so
R
1% standard values have been chosen).
V
The LTC2919 contains an accurate third -10% undervoltage
monitor on the V
11.5% below the V
standard part (LTC2919-2.5) is confi gured to monitor a
2.5V supply (UVLO threshold of 2.213V), but versions
to monitor 3.3V and 5.0V (UVLO of 2.921V and 4.425V,
respectively) are available.
For applications that do not need V
2.5V version should be used, and the UVLO will simply
guarantee that the V
proper threshold and timer accuracy before the timeout
begins.
Setting the Reset Timeout
RST goes high after a reset timeout period set by the TMR
pin when the V
timeout may be confi gured in one of three ways: internal
200ms, programmed by external capacitor and no timeout
(comparator mode).
In externally-controlled mode, the TMR pin is connected
by a capacitor to ground. The value of that capacitor allows
for selection of a timeout ranging from about 400μs to 9
seconds. See the following section for details.
N4
CC
Figure 4. Setting UV and OV Trip Point for a Negative Supply
= 100k. We then fi nd R
Monitoring/UVLO
–V
MON
R
R
R
N4
N5
N6
REF
ADJ1
ADJ2
0.5V
CC
CC
+
–
and ADJ inputs are valid. This reset
pin. This monitor is fi xed at a nominal
CC
CC
is above the minimum required for
+
–
+
–
specifi ed in the part number. The
OV
N5
= –5.575V and V
= 21.0k, R
MOSFET
MOSFET
DRAIN
DRAIN
LOGIC
LOGIC
OPEN
OPEN
&
&
CC
N6
= 1.18M (nearest
monitoring, the
OUT1
OUT2
2919 F04
UV
= –4.425V.
OV
UV
2919f