FEATURES
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LTC2911
Precision Triple Supply
Monitor with Power-Fail
Comparator
DESCRIPTION
The LTC
®
2911 is a low power, high accuracy triple supply
monitor with a power-fail comparator. Reset timeout may
be selected with an external capacitor or set to an internally
generated 200ms.
The V1 pin monitors a 3.3V supply. The V2 pin monitors a
5V, 2.5V, 1.8V, 1.2V or adjustable supply. A third adjustable
input has a nominal 0.5V threshold allowing a resistive
divider to configure its threshold. All three comparators
feature a tight 1.5% threshold accuracy over the entire
operating temperature range while a glitch filter ensures
reliable reset operation.
A spare comparator can be configured to provide early
warning of a low voltage condition. It causes the
PFO
output
to pull low when the voltage of the PFI input falls below 0.5V,
allowing the power-fail threshold to be configured with
a resistive divider. A latch feature on the TMR pin allows
the
RST
output to be latched to prevent system resets,
simplifying margin testing.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 6949965, 7292076.
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Ultralow Voltage Reset: V
CC
= 0.5V Guaranteed
Monitors Three Inputs Simultaneously:
3.3V, 5V, ADJ (LTC2911-1)
3.3V, 2.5V, ADJ (LTC2911-2)
3.3V, 1.8V, ADJ (LTC2911-3)
3.3V, 1.2V, ADJ (LTC2911-4)
3.3V, ADJ, ADJ (LTC2911-5)
±1.5% Threshold Accuracy
Power-Fail Monitor
RST
State Can Be Held for Margining
Low Supply Current: 30µA Typical
Input Glitch Immunity
Adjustable Reset Timeout Period
Selectable Internal Timeout Saves Components
Space Saving 8-Lead TSOT-23 and 3mm
×
2mm DFN
Packages
APPLICATIONS
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Network Servers
Desktop and Notebook Computers
Automotive and Industrial Electronics
TYPICAL APPLICATION
RST
Output Voltage With 10k Pull-Up to V1
3.3V
2.5V
DC/DC
CONVERTER 1.0V
TMR
V1
76.8k
RESET
LOBAT
10k
V
RST
(V)
SYSTEM
LOGIC
6
5
4
3
2
1
t
RST
= 200ms
2911 TA01a
V1 = V2
RST
V2
PFO
LTC2911-2
ADJ
PFI
+
Li-Ion
BATTERY
STACK
576k
100k
100k
GND
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
V1 (V)
2911 TA01b
2911f
1
LTC2911
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2, 3)
Supply Voltages
V1, V2 ................................................... –0.3V to 6.5V
Input Voltages
ADJ ....................................................... –0.3V to 6.5V
PFI ........................................................... –0.3V to 2V
TMR ............................................–0.3V to (V1 + 0.3V)
Output Voltages
RST, PFO
.............................................. –0.3V to 6.5V
Operating Temperature Range
LTC2911C ................................................ 0°C to 70°C
LTC2911I.............................................. –40°C to 85°C
LTC2911H .......................................... –40°C to 125°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
TSOT-23 ............................................................ 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
PFI 1
ADJ 2
TMR 3
GND 4
8 V2
7 V1
6
PFO
5
RST
V2 1
V1 2
PFO
3
RST
4
9
GND
8 PFI
7 ADJ
6 TMR
5 GND
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
T
JMAX
= 150°C,
θ
JA
= 195°C/W
DDB PACKAGE
8-LEAD (3mm
×
2mm) PLASTIC DFN
T
JMAX
= 150°C,
θ
JA
= 76°C/W
EXPOSED PAD (PIN 9) IS GND, PCB CONNECTION OPTIONAL
ORDER INFORMATION
LTC2911 C
DDB –1
#TRM
PBF
LEAD FREE DESIGNATOR
PBF = Lead Free Finish Parts
None = Lead Based Finish Parts
TAPE AND REEL
#TR = Tape and Reel
#TRM = 500-Piece Tape and Reel
PRODUCT SELECTION
–1, –2, –3, –4, –5
See Product Selection Guide for Details
PACKAGE TYPE
DDB = 8-Lead (3mm
×
2mm) Plastic DFN
TS8 = 8-Lead Plastic TSOT-23
TEMPERATURE GRADE
C = Commercial Temperature Range (0°C to 70°C)
I = Industrial Temperature Range (–40°C to 85°C)
H = Automotive Temperature Range (–40°C to 125°C)
PRODUCT PART NUMBER
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
2911f
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LTC2911
PRODUCT SELECTION GUIDE
PART NUMBER
LTC2911-1
LTC2911-2
LTC2911-3
LTC2911-4
LTC2911-5
LTC2911-1
LTC2911-2
LTC2911-3
LTC2911-4
LTC2911-5
PART MARKING
LFHZ
LFPG
LFPJ
LFPM
LFPP
LTFJB
LTFPH
LTFPK
LTFPN
LTFPQ
PACKAGE DESCRIPTION
8-Lead (3mm
×
2mm) Plastic DFN
8-Lead (3mm
×
2mm) Plastic DFN
8-Lead (3mm
×
2mm) Plastic DFN
8-Lead (3mm
×
2mm) Plastic DFN
8-Lead (3mm
×
2mm) Plastic DFN
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
V1
3.3V
3.3V
3.3V
3.3V
3.3V
3.3V
3.3V
3.3V
3.3V
3.3V
V2
5V
2.5V
1.8V
1.2V
ADJ
5V
2.5V
1.8V
1.2V
ADJ
ELECTRICAL CHARACTERISTICS
SYMBOL
V
RT33
V
RT50
V
RT25
V
RT18
V
RT12
V
RTA
V
PFT
∆V
PFT
V
CC,OP
I
V1
I
V2
PARAMETER
3.3V, 5% Reset Threshold
5V, 5% Reset Threshold
2.5V, 5% Reset Threshold
1.8V, 5% Reset Threshold
1.2V, 5% Reset Threshold
ADJ Pin Threshold
PFI Pin Threshold
PFI Hysteresis
Minimum Operating Voltage to Guarantee
PFO
High (Note 3)
V1 input Current (Note 4)
V2 Input Current (Note 4)
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
ADJ
= 0.55V, V
PFI
= 0.55V, V1 = 3.3V unless otherwise noted. (Notes 2, 3)
CONDITIONS
V1 Input
V2 Input (LTC2911-1)
V2 Input (LTC2911-2)
V2 Input (LTC2911-3)
V2 Input (LTC2911-4)
ADJ Input and V2 Input of
LTC2911-5
PFI Input Threshold (Falling)
V
PFI
= 0.55V
V1 = 3.3V, V1 > V2
V1 = 3.3V, V1 < V2
V2 = 5V (LTC2911-1)
V2 = 2.5V (LTC2911-2)
V2 = 1.8V (LTC2911-3)
V2 = 1.2V (LTC2911-4)
V2 = 0.55V (LTC2911-5)
C-Grade/I-Grade
H-Grade
V
ADJ
= 0.55V (C-Grade) (I-Grade)
V
ADJ
= 0.55V (H-Grade)
V
PFI
= 0.55V (C-Grade) (I-Grade)
V
PFI
= 0.55V (H-Grade)
V
TMR
= 1V
V
TMR
= 1V
V
PIN
= 0V
l
l
l
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l
l
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l
l
l
l
l
l
MIN
3.036
4.600
2.300
1.656
1.104
492.5
492.5
10
TYP
3.086
4.675
2.338
1.683
1.122
500
500
15
MAX
3.135
4.750
2.375
1.710
1.140
507.5
507.5
19
2.3
UNITS
V
V
V
V
V
mV
mV
mV
V
µA
µA
µA
µA
µA
µA
nA
nA
nA
nA
nA
nA
µA
µA
µA
10
3
10
3
2
2
30
10
35
10
10
10
80
30
80
30
30
30
±15
±40
±15
±40
±15
±40
I
ADJ
I
PFI
I
TMR(UP)
I
TMR(DOWN)
I
PU
ADJ Input Current
PFI Input Current
TMR Pull-Up Current
TMR Pull-Down Current
RST, PFO
Pull-Up Current
–1.5
1.5
–20
–2.2
2.2
–29
–2.9
2.9
–40
2911f
3
LTC2911
ELECTRICAL CHARACTERISTICS
SYMBOL
t
P,PF
t
UV
V
OH
V
OL
t
RST(EXT)
t
RST(INT)
V
TMR(INT)
∆V
TMR(INT)
V
TMR(LATCH)
t
P,LR
t
SU,MON
t
HD, MON
PARAMETER
PFI Comparator Propagation Delay to
PFO
V1, V2, ADJ Undervoltage Detect to
RST
Low
RST, PFO
Output Voltage High (Note 5)
RST, PFO
Output Voltage Low (Note 6)
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
ADJ
= 0.55V, V
PFI
= 0.55V, V1 = 3.3V unless otherwise noted. (Notes 2, 3)
CONDITIONS
V
PFI
Driven Beyond Threshold
V
PFT
by More Than 10%
V
X
Less Than Threshold V
RTX
by
More Than 10%
I
RST
= –1µA
V
CC
= 0.5V, I = 5µA
V
CC
= 1V, I = 100µA
V
CC
= 3V, I = 2.5mA
C
TMR
= 2.2nF
V
TMR
= V1
V
TMR
Rising
V
TMR
Falling
V
TMR
Falling
V
TMR
Rising
V
TMR
Rising, Step 0V to 0.6V
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
MIN
8
8
V1 – 1
TYP
30
30
MAX
80
80
V1
UNITS
µs
µs
V
V
V
V
ms
ms
V
mV
V
mV
µs
ms
µs
0.01
0.01
0.10
15
140
V1 – 0.40
40
0.10
40
2
0
20
200
V1 – 0.020
100
0.20
75
0.5
0.15
0.15
0.30
27
280
V1 – 0.10
160
0.40
160
3
Reset Timeout Period, External
Reset Timeout Period, Internal
Timer Internal Mode Threshold
Timer Internal Mode Hysteresis
Timer Latch Mode Threshold
Latch Release Propagation Delay to
RST
Low
∆V
TMR(LATCH)
Timer Latch Mode Hysteresis
Monitor Input Setup Time to Latch Enable (Note 7) V
TMR
Falling, Step 0.6V to 0V
Monitor Input Setup Time to Latch Release
V
TMR
Rising, Step 0V to 0.6V
Monitor Input Hold Time to Latch Enable
Monitor Input Hold Time to Latch Release
V
TMR
Falling, Step 0.6V to 0V
V
TMR
Rising, Step 0V to 0.6V
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:
The internal supply voltage (V
CC
) is generated from the greater of
the voltages on the V1 and V2 inputs. V
CC
= V1 for the LTC2911-5.
Note 4:
Under typical operating conditions, quiescent current is drawn
from the greater of the voltages on the V1 and V2 inputs. For the
LTC2911-5 only V1 supplies the quiescent current.
Note 5:
The
RST
and
PFO
output pins on the LTC2911 have internal pull-
ups to V1. However, for faster rise times or for V
OH
voltages greater than
V1, use an external pull-up resistor.
Note 6:
The
RST
and
PFO
pull-down currents are derived from V1 and V2
except for the LTC2911-5 where the pull-down strength is derived only
from V1.
Note 7:
t
SU,MON
is required to latch a low
RST
state and t
SU,MON
+ t
RST
is
required to latch a high
RST
state.
2911f
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LTC2911
TYPICAL PERFORMANCE CHARACTERISTICS
Normalized Reset and Power-Fail
Threshold Voltages vs Temperature
NORMALIZED THRESHOLD VOLTAGE (V/V)
1.015
1.010
1.005
1.000
0.995
0.990
0.985
–50
QUIESCENT SUPPLY CURRENT (µA)
60
50
40
30
20
10
0
–50
GLITCH DURATION (µs)
Quiescent Supply Current
vs Temperature
I
V2
FOR LTC2911-1
500
400
Allowable Glitch Duration
vs Overdrive
300
200
100
0
–25
75
0
50
25
TEMPERATURE (°C)
100
125
–25
75
0
50
25
TEMPERATURE (°C)
100
125
0.1
1
10
100
2911 G03
OVERDRIVE (%)
2911 G02
2911 G01
PFI Hysteresis vs Temperature
18.0
17.5
TIMEOUT PERIOD (ms)
17.0
HYSTERESIS (mV)
16.5
16.0
15.5
15.0
14.5
14.0
–50
–25
0
50
25
T
AMB
(°C)
75
100
125
260
240
220
200
180
160
Reset Timeout Period vs
Temperature
1.0
RST, PFO
Voltage Output Low
vs Sink Current
V
CC
= 3V
INTERNAL
EXTERNAL
C
TMR
= 22nF
VOLTAGE OUTPUT LOW (V)
0.8
0.6
0.4
–40°C
25°C
85°C
125°C
150°C
0
5
10
15
20
SINK CURRENT (mA)
25
30
2911 G06
0.2
0
140
–50
–25
75
0
50
25
TEMPERATURE (°C)
100
125
2911 G04
2911 G05
RST, PFO
Voltage Output High
vs Source Current
3.0
2.5
VOLTAGE OUTPUT HIGH (V)
2.0
1.5
1.0
0.5
0
V1 = 3.135V, V2 = 5V FOR
RST
6
5
4
3
2
1
0
0
5
20
15
25
10
SOURCE CURRENT (µA)
30
35
–1
RST, PFO
Voltage Output High
vs V
CC
OUTPUT SOURCE CURRENT (µA)
V1 = V2 = ADJ = PFI
10k PULL-UP TO V
CC
RST
FOR
LTC2911-1
RST
FOR
LTC2911-2
LTC2911-3
LTC2911-4
LTC2911-5
RST, PFO
Pin Source Current
vs V1
100
VOLTAGE OUTPUT HIGH (V)
80
60
40
PFO
20
PFO
0
1
2
RST
3
V1 (V)
4
5
6
2911 G09
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
V
CC
(V)
2911 G08
0
2911 G07
2911f
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PCB设计
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