LTC2909
Precision Triple/Dual Input
UV, OV and Negative
Voltage Monitor
FEATURES
■
■
DESCRIPTIO
■
■
■
■
■
■
■
■
■
■
■
Two Low Voltage Adjustable Inputs (0.5V)
Pin Selectable Input Polarity Allows Negative
and OV Monitoring
Guaranteed Threshold Accuracy: ±1.5%
6.5V Shunt Regulator for High Voltage Operation
Low 50μA Quiescent Current
Buffered 1V Reference for Negative Supply Offset
Input Glitch Rejection
Adjustable Reset Timeout Period
Selectable Internal Timeout Saves Components
Open-Drain
⎯
R
⎯
S
⎯
T Output
Accurate UVLO for 2.5V, 3.3V, 5V Systems
Ultralow Voltage Reset: V
CC
= 0.5V Guaranteed
Space Saving 8-Lead TSOT-23 and 3mm
×
2mm DFN
Packages
The LTC
®
2909 is a dual input monitor intended for a variety
of system monitoring applications. Polarity selection and
a buffered reference output allow the LTC2909 to monitor
positive and negative supplies for undervoltage (UV) and
overvoltage (OV) conditions.
The two inputs have a nominal 0.5V threshold, featuring
tight 1.5% threshold accuracy over the entire operating
temperature range. Glitch filtering ensures reliable reset
operation without false triggering. A third fixed-threshold
UVLO monitor on the part’s V
CC
(also 1.5% accuracy) is
available for standard logic supplies.
The common reset output has a timeout that may use
a preset 200ms, be set by an external capacitor or be
disabled. A three-state input pin sets the input polarity
of each adjustable input without requiring any external
components.
The LTC2909 provides a highly versatile, precise, space-
conscious, micropower solution for supply monitoring.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
■
■
■
■
■
Desktop and Notebook Computers
Handheld Devices
Network Servers
Core, I/O Monitor
Automotive
TYPICAL APPLICATIO
3.3V UV/OV (Window) Monitor Application with
200ms Internal Timeout (3.3V Logic Out)
C
BYP
100nF
3.3V
R
P6
453k
ADJ1
R
P5
10.7k
V
CC
RST
LTC2909-2.5
REF
ADJ2
R
P4
76.8k
GND
2909 TA01a
SEL Pin Connection for Input Polarity
Combinations
POLARITY
R
PU
10k
FAULT
OUTPUT
ADJ1
+
+
–
SEL
TMR
U
ADJ2
SEL PIN
V
CC
OPEN
GND
U
U
+
–
–
2909fb
1
LTC2909
ABSOLUTE
AXI U RATI GS
Terminal Voltages
V
CC
(Note 3)............................................. –0.3V to 6V
SEL,
⎯
R
⎯
S
⎯
T .............................................. –0.3V to 7.5V
ADJ1, ADJ2 .......................................... –0.3V to 7.5V
TMR ..........................................–0.3V to (V
CC
+ 0.3V)
Terminal Currents
I
VCC
(Note 3) ....................................................±10mA
I
REF
....................................................................±1mA
PACKAGE/ORDER I FOR ATIO
TOP VIEW
SEL 1
TMR 2
V
CC
3
RST 4
9
8
7
6
5
ADJ1
ADJ2
REF
GND
DDB PACKAGE
8-LEAD (3mm
´
2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 76°C/W
EXPOSED PAD (PIN 9) MAY BE LEFT OPEN OR TIED TO GND
(PCB CONNECTION REQUIRED FOR STATED
θ
JA
)
TOP VIEW
ADJ1 1
ADJ2 2
REF 3
GND 4
8 SEL
7 TMR
6 V
CC
5 RST
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
T
JMAX
= 125°C,
θ
JA
= 250°C/W
Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
*The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for parts specified with wider operating temperature ranges.
2
U
U
W
W W
U
W
(Notes 1, 2)
Operating Temperature Range
LTC2909C ................................................ 0°C to 70°C
LTC2909I .............................................– 40°C to 85°C
Storage Temperature Range
DFN....................................................– 65°C to 125°C
TSOT-23.............................................– 65°C to 150°C
Lead Temperature (Soldering, 10 sec)
TSOT-23............................................................ 300°C
ORDER PART
NUMBER
LTC2909CDDB-2.5
LTC2909IDDB-2.5
LTC2909CDDB-3.3
LTC2909IDDB-3.3
LTC2909CDDB-5
LTC2909IDDB-5
DDB PART*
MARKING
LBXG
LBXG
LBZS
LBZS
LBZT
LBZT
ORDER PART
NUMBER
LTC2909CTS8-2.5
LTC2909ITS8-2.5
LTC2909CTS8-3.3
LTC2909ITS8-3.3
LTC2909CTS8-5
LTC2909ITS8-5
TS8 PART*
MARKING
LTBXF
LTBXF
LTBZV
LTBZV
LTBZW
LTBZW
2909fb
LTC2909
ELECTRICAL CHARACTERISTICS
SYMBOL
V
CC(MIN)
V
CC(SHUNT)
I
CC
V
RT
ΔV
RT
I
ADJ
V
CC(UVLO)
PARAMETER
Operating Supply Voltage
V
CC
Shunt Regulation Voltage
V
CC
Input Current
ADJ Input Threshold
ADJ Hysteresis (Note 4)
ADJ Input Current
V
CC
UVLO Threshold
TMR = V
CC
V
ADJ
= 0.55V
LTC2909-2.5
LTC2909-3.3
LTC2909-5
TMR = V
CC
V
CC
> 2.175V, I
VREF
= ±1mA
V
TMR
= 1V
V
TMR
= 1V
C
TMR
= 2.2nF
V
TMR
= 0V
V
TMR
Rising
V
TMR
Falling
V
TMR
Falling
V
TMR
Rising
ADJx Driven Beyond Reset Threshold
(V
RTX
) by 5mV
V
CC
Less Than UVLO Threshold
(V
CC(UVLO)
) by 1%
V
CC
= 0.5V, I = 5μA
V
CC
= 1V, I = 100μA
V
CC
= 3V, I = 2500μA
⎯
RS
⎯
T = V
CC
⎯
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 2.5V (LTC2909-2.5), V
CC
= 3.3V (LTC2909-3.3), V
CC
= 5V
(LTC2909-5), ADJ1 = ADJ2 = 0.55V, SEL = floating, unless otherwise noted. (Note 2)
CONDITIONS
⎯
RS
⎯
T in Correct State
⎯
I
VCC
= 1mA, I
VREF
= 0
2.175 < V
CC
< 6V
●
●
●
●
MIN
0.5
6.0
0.4925
1.5
2.175
2.871
4.350
0.3
0.985
–1.5
1.5
16
150
V
CC
– 0.36
60
0.14
40
50
50
TYP
6.5
50
0.5000
3.5
2.213
2.921
4.425
0.7
1.000
–2.1
2.1
20
200
V
CC
– 0.25
110
0.21
70
150
150
0.01
0.01
0.10
MAX
6.9
150
0.5075
10.0
±15
2.250
2.970
4.500
2.0
1.015
–2.7
2.7
25
260
V
CC
– 0.16
150
0.27
110
500
500
0.15
0.15
0.30
±1
0.4
UNITS
V
V
μA
V
mV
nA
V
V
V
%
V
μA
μA
ms
ms
V
mV
V
mV
μs
μs
V
V
V
μA
V
V
V
μA
μA
ΔV
CC(UVLO)
V
REF
I
TMR(UP)
I
TMR(DOWN)
t
⎯
R
⎯
S
⎯
T(EXT)
t
⎯
R
⎯
S
⎯
T(INT)
V
TMR(DIS)
ΔV
TMR(DIS)
V
TMR(INT)
ΔV
TMR(INT)
t
PROP
t
UV
V
OL(
⎯
R
⎯
S
⎯
T)
UVLO Hysteresis (Note 4)
Buffered Reference Voltage
TMR Pull-Up Current
TMR Pull-Down Current
Reset Timeout Period, External
Reset Timeout Period, Internal
Timer Disable Voltage
Timer Disable Hysteresis
Timer Internal Mode Voltage
Timer Internal Mode Hysteresis
ADJx Comparator Propagation Delay
to
⎯
R
⎯
S
⎯
T
V
CC
Undervoltage Detect to
⎯
R
⎯
S
⎯
T
⎯
RS
⎯
T Output Voltage Low
⎯
I
OH(
⎯
R
⎯
S
⎯
T)
V
IL
V
IH
V
Z
I
SEL(Z)
I
SEL
⎯
RS
⎯
T Output Voltage High Leakage
⎯
Low Level Input Voltage
High Level Input Voltage
Pin Voltage when Left in Open State
Allowable Leakage in Open State
SEL Input Current
Three-State Input SEL
●
●
1.4
0.9
±5
±10
±25
I
SEL
= 0μA
●
SEL = V
CC
or SEL = GND
●
μA
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
All currents into pins are positive; all voltages are referenced to
GND unless otherwise noted.
Note 3:
V
CC
maximum pin voltage is limited by input current. Since the
V
CC
pin has an internal 6.5V shunt regulator, a low impedance supply
which exceeds 6V may exceed the rated terminal current. Operation
from higher voltage supplies requires a series dropping resistor. See
Applications Information.
Note 4:
Threshold voltages have no hysteresis unless the part is in
comparator mode. Hysteresis is one-sided, affecting only invalid-to-valid
transitions. See Applications Information.
2909fb
3
LTC2909
TYPICAL PERFOR A CE CHARACTERISTICS
T
A
= 25°C unless otherwise noted
THRESHOLD VOLTAGE VARIATION (% OF 25°C VALUE)
ADJ Threshold Voltage
vs Temperature
508
THRESHOLD VOLTAGE, V
RT
(mV)
506
504
502
500
498
496
494
492
–50
–25
0
50
75
25
TEMPERATURE (°C)
100
125
REF VOLTAGE, V
REF
(V)
REF Output Load Regulation
1.015
1.010
REF VOLTAGE, V
REF
(V)
1.005
1.000
T
A
= –40°C
0.995
0.990
0.985
–1
–0.5
0
0.5
LOAD CURRENT, I
REF
(mA)
1
2909 G04
1.010
T
A
= 125°C
T
A
= 25°C
REF VOLTAGE, V
REF
(V)
1.005
T
A
= 125°C
T
A
= 25°C
T
A
= –40°C
QUIESCENT SUPPLY CURRENT, I
CC
(μA)
V
CC
= 2.5V
Allowable Glitch Duration
vs Magnitude
700
600
MAXIMUM ALLOWABLE
GLITCH DURATION (μs)
500
400
300
200
100
0
0.1
1
10
100
GLITCH PERCENTAGE PAST THRESHOLD (%)
2909 G07
RESET TIMEOUT PERIOD, t
RST
(ms)
RESET TIMEOUT PERIOD, t
RST
(ms)
RESET OCCURS
ABOVE CURVE
4
U W
2909 G01
V
CC
UVLO Threshold Variation
vs Temperature
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
–50
0.015
1.010
1.005
1.000
0.995
0.990
REF Output Voltage
vs Temperature
I
REF
= 0A
–25
50
25
75
0
TEMPERATURE (°C)
100
125
0.985
–50
–25
50
25
75
0
TEMPERATURE (°C)
100
125
2909 G02
2909 G03
REF Output Line Regulation
1.015
I
REF
= 0A
60
Quiescent Supply Current
vs Temperature
ADJ1 = 0.55V
55 ADJ2 = 0.45V
SEL = OPEN
50
45
40
35
30
25
20
–50
–25
0
50
75
25
TEMPERATURE (°C)
100
125
V
CC
= 2.5V
V
CC
= 5V
V
CC
= 3.3V
1.000
0.995
0.990
0.985
2
2.5
4.5 5
3 3.5 4
SUPPLY VOLTAGE, V
CC
(V)
5.5
6
2909 G05
2909 G06
External Timeout Period
vs Capacitance
10000
260
240
Reset Timeout Period
vs Temperature
1000
EXTERNAL WITH
22nF CAPACITOR
220
200
180
160
140
–50
INTERNAL
100
10
1
0.1
1
10
100
TMR PIN CAPACITANCE, C
TMR
(nF)
1000
2909 G08
–25
50
25
75
0
TEMPERATURE (°C)
100
125
2909 G09
2909fb
LTC2909
TYPICAL PERFOR A CE CHARACTERISTICS
Shunt Regulation Voltage
vs Temperature
SHUNT REGULATION VOLTAGE, V
CC(SHUNT)
(V)
SHUNT REGULATION VOLTAGE, V
CC(SHUNT)
(V)
7.0
7.0
6.8
I
CC
= 10mA
6.6
I
CC
= 1mA
I
CC
= 100μA
RST VOLTAGE (V)
6.4
6.2
6.0
–50 –25
50
25
0
75
TEMPERATURE (°C)
⎯
RS
⎯
T Output Voltage vs V
CC
⎯
0.4
PULL-DOWN CURRENT, I
RST
(mA)
6
PULL-DOWN CURRENT, I
RST
(mA)
0.3
RST VOLTAGE (V)
V
CC
0.2
RST WITH 10k PULL-UP
0.1
RST WITH 100k PULL-UP
0
0
0.1
0.2 0.3 0.4 0.5 0.6 0.7
SUPPLY VOLTAGE, V
CC
(V)
0.8
⎯
RS
⎯
T V
OL
vs I
⎯
R
⎯
S
⎯
T
⎯
1.0
V
CC
= 3V
NO PULL-UP R
T
A
= 125°C
RST V
OL
(V)
T
A
= 25°C
I
SEL
(μA)
0.6
T
A
= –40°C
0.4
–20
0.8
–14
I
SEL
(μA)
0.2
0
0
5
10
15
20
I
RST
(mA)
U W
100
2909 G13
T
A
= 25°C unless otherwise noted
Shunt Regulation Voltage
vs Supply Current
T
A
= 25°C
5
⎯
RS
⎯
T Output Voltage vs V
CC
⎯
ADJ1 = 0.55
ADJ2 = 0.45
4 SEL = OPEN
10k PULL-UP R TO V
CC
3
6.8
6.6
6.4
2
LTC2909-2.5
1
LTC2909-3.3
LTC2909-5
6.2
125
6.0
0.01
0
0.1
1
10
SUPPLY CURRENT, I
CC
(mA)
100
2909 G11
0
1
3
4
2
SUPPLY VOLTAGE, V
CC
(V)
5
2909 G12
2909 G10
⎯
RS
⎯
T Pull-Down Current vs V
CC
⎯
ADJ1 = 0.55
ADJ2 = 0.55
5 SEL = OPEN
4
RST AT 150mV
3
2
1
0
0
1
2
3
4
SUPPLY VOLTAGE, V
CC
(V)
5
2909 G14
⎯
RS
⎯
T Pull-Down Current vs V
CC
⎯
1
RST AT 150mV
0.1
RST AT 50mV
0.01
0.001
RST AT 50mV
0.0001
0
0.2
0.4
0.6
0.8
SUPPLY VOLTAGE, V
CC
(V)
1
2909 G15
I
SEL
vs Temperature
SEL = GND
20
I
SEL
vs Temperature
SEL = V
CC
–18
18
–16
16
14
–12
12
25
30
1635 G07
–10
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
10
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
2909 G17
2909 G18
2909fb
5
聊聊、笑笑、闹闹
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
