FEATURES
■
LTC2917/LTC2918
Low Voltage Supervisor
with 27 Selectable Thresh-
olds and Watchdog Timer
DESCRIPTION
The LTC
®
2917-A/LTC2917-B and LTC2918-A/LTC2918-B
are low voltage single-supply monitors with selectable
thresholds and an adjustable watchdog timer. The parts
operate from 1.5V to 5.5V and consume a quiescent cur-
rent of only 30μA.
Two three state inputs select one of nine internally pro-
grammed thresholds without the need for external resistors.
For the LTC2917, an additional three state input determines
the tolerance (–5%, –10%, –15%). The tolerance for the
LTC2918 is fixed at –5%. Threshold accuracy is guaranteed
at ±1.5% over the entire operating temperature range.
Glitch filtering ensures reliable reset operation without
false triggering.
The reset timeout and the watchdog timeout may be set
with no external components, or adjusted using an exter-
nal capacitor. A windowed watchdog feature is available
for high-reliability applications (B1 versions). A separate
manual reset input on the LTC2918-A/LTC2918-B allows
a simple push button interface.
Operation to 125°C makes the LTC2917-A/LTC2917-B
and LTC2918-A/LTC2918-B suitable for automotive ap-
plications.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
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9 Selectable Supply Voltages
12V, 5V, 3.3V, 2.5V, 1.8V
1.5V, 1.2V, 1V, +ADJ (0.5V)
3 Selectable Tolerances
–5%, –10%, –15% (LTC2917)
Manual Reset Input (LTC2918)
1.5V to 5.5V Supply Operation
Adjustable Watchdog Timeout
Windowed Watchdog Timeout for Higher Reliability
Applications (LTC2917-B, LTC2918-B)
6.2V Shunt Regulator for High Voltage Operation
Guaranteed to 125˚C
Guaranteed Threshold Accuracy: ±1.5%
Low Quiescent Current: 30μA Typical
Power Supply Glitch Immunity
Guaranteed
⎯
R
⎯
S
⎯
T for V
CC
≥ 0.8V
10-Lead MSOP Packages and (3mm
×
2mm) DFN
Packages
APPLICATIONS
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■
Handheld Devices
Cell Phone Base Stations
Automotive Control Systems
Network Servers
Optical Networking Systems
TYPICAL APPLICATION
1.8V Supply Monitor with Manual
Reset and Internal Timers Selected
1.8V
Monitor Selection Table
NOMINAL VOLTAGE
SEL1
V
CC
V
CC
V
CC
Open
Open
Open
GND
GND
GND
SEL2
V
CC
Open
GND
V
CC
Open
GND
V
CC
Open
GND
29178f
0.1μF
10k
12V
5V
3.3V
μP
RST
I/O
29178 TA01
V
CC
LTC2918-A
VM
RT
WT
MR
GND
t
WDU
= 1.6s
t
RST
= 200ms
RST
WDI
SEL1
SEL2
2.5V
1.8V
1.5V
1.2V
1V
ADJ (0.5V)
1
LTC2917/LTC2918
ABSOLUTE MAXIMUM RATINGS
(Note 1, 2)
Terminal Voltages
V
CC
(Note 3).......................................... –0.3V to 5.7V
SEL1, SEL2, TOL, WDI,
⎯
M
⎯
R,
⎯
R
⎯
S
⎯
T ......... –0.3V to 7.5V
VM ......................................................... –0.3V to 15V
RT, WT ......................................–0.3V to (V
CC
+ 0.3)V
Terminal Currents
V
CC
(Note 3).......................................................±5mA
Operating Temperature Range
LTC2917C/LTC2918C ............................... 0°C to 70°C
LTC2917I/LTC2918I ............................. –40°C to 85°C
LTC2917H/LTC2918H ........................ –40°C to 125°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
MSOP-10 .......................................................... 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
GND
TOL
SEL2
SEL1
VM
1
2
3
4
5
10
9
8
7
6
RST
RT
WT
WDI
V
CC
GND 1
TOL 2
SEL2 3
SEL1 4
VM 5
11
10 RST
9
8
7
6
RT
WT
WDI
V
CC
MS PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 200°C/W
LTC2917
DDB PACKAGE
10-LEAD (3mm
×
2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 11) PCB GND
CONNECTION OPTIONAL
LTC2917
TOP VIEW
TOP VIEW
GND
MR
SEL2
SEL1
VM
1
2
3
4
5
10
9
8
7
6
RST
RT
WT
WDI
V
CC
GND 1
MR 2
SEL2 3
SEL1 4
VM 5
11
10 RST
9
8
7
6
RT
WT
WDI
V
CC
MS PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 200°C/W
LTC2918
DDB PACKAGE
10-LEAD (3mm
×
2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 11) PCB GND
CONNECTION OPTIONAL
LTC2918
29178f
2
LTC2917/LTC2918
ORDER INFORMATION
LEAD FREE FINISH
LTC2917CMS-B1#PBF
LTC2917IMS-B1#PBF
LTC2917HMS-B1#PBF
LTC2917CMS-A1#PBF
LTC2917IMS-A1#PBF
LTC2917HMS-A1#PBF
LTC2918CMS-B1#PBF
LTC2918IMS-B1#PBF
LTC2918HMS-B1#PBF
LTC2918CMS-A1#PBF
LTC2918IMS-A1#PBF
LTC2918HMS-A1#PBF
TAPE AND REEL (MINI)
LTC2917CDDB-B1#TRMPBF
LTC2917IDDB-B1#TRMPBF
LTC2917HDDB-B1#TRMPBF
LTC2917CDDB-A1#TRMPBF
LTC2917IDDB-A1#TRMPBF
LTC2917HDDB-A1#TRMPBF
LTC2918CDDB-B1#TRMPBF
LTC2918IDDB-B1#TRMPBF
LTC2918HDDB-B1#TRMPBF
LTC2918CDDB-A1#TRMPBF
LTC2918IDDB-A1#TRMPBF
LTC2918HDDB-A1#TRMPBF
TAPE AND REEL
LTC2917CMS-B1#TRPBF
LTC2917IMS-B1#TRPBF
LTC2917HMS-B1#TRPBF
LTC2917CMS-A1#TRPBF
LTC2917IMS-A1#TRPBF
LTC2917HMS-A1#TRPBF
LTC2918CMS-B1#TRPBF
LTC2918IMS-B1#TRPBF
LTC2918HMS-B1#TRPBF
LTC2918CMS-A1#TRPBF
LTC2918IMS-A1#TRPBF
LTC2918HMS-A1#TRPBF
TAPE AND REEL
LTC2917CDDB-B1#TRPBF
LTC2917IDDB-B1#TRPBF
LTC2917HDDB-B1#TRPBF
LTC2917CDDB-A1#TRPBF
LTC2917IDDB-A1#TRPBF
LTC2917HDDB-A1#TRPBF
LTC2918CDDB-B1#TRPBF
LTC2918IDDB-B1#TRPBF
LTC2918HDDB-B1#TRPBF
LTC2918CDDB-A1#TRPBF
LTC2918IDDB-A1#TRPBF
LTC2918HDDB-A1#TRPBF
PART MARKING*
LTCQP
LTCQP
LTCQP
LTDGD
LTDGD
LTDGD
LTDCT
LTDCT
LTDCT
LTDGG
LTDGG
LTDGG
PART MARKING*
LCQR
LCQR
LCQR
LDGF
LDGF
LDGF
LDCV
LDCV
LDCV
LDGH
LDGH
LDGH
PACKAGE DESCRIPTION
10-Lead Plastic MSOP
10-Lead Plastic MSOP
10-Lead Plastic MSOP
10-Lead Plastic MSOP
10-Lead Plastic MSOP
10-Lead Plastic MSOP
10-Lead Plastic MSOP
10-Lead Plastic MSOP
10-Lead Plastic MSOP
10-Lead Plastic MSOP
10-Lead Plastic MSOP
10-Lead Plastic MSOP
PACKAGE DESCRIPTION
10-Lead (3mm
×
2mm) Plastic DFN
10-Lead (3mm
×
2mm) Plastic DFN
10-Lead (3mm
×
2mm) Plastic DFN
10-Lead (3mm
×
2mm) Plastic DFN
10-Lead (3mm
×
2mm) Plastic DFN
10-Lead (3mm
×
2mm) Plastic DFN
10-Lead (3mm
×
2mm) Plastic DFN
10-Lead (3mm
×
2mm) Plastic DFN
10-Lead (3mm
×
2mm) Plastic DFN
10-Lead (3mm
×
2mm) Plastic DFN
10-Lead (3mm
×
2mm) Plastic DFN
10-Lead (3mm
×
2mm) Plastic DFN
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
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/
29178f
3
LTC2917/LTC2918
ELECTRICAL CHARACTERISTICS
SYMBOL
V
CC(MIN)
V
CC(UVLO)
V
CC(SHUNT)
I
CC
PARAMETER
Minimum Supply Voltage
Supply Undervoltage Lockout
Shunt Regulation Voltage
V
CC
Pin Current
I
VCC
= 0.5mA
SEL1, SEL2, TOL,
⎯
M
⎯
R = Open
SEL1, SEL2, TOL = GND (LTC2917)
⎯
M
⎯
R = V
CC
(LTC2918)
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 2.5V, unless otherwise noted. (Note 2)
CONDITIONS
⎯
RS
⎯
T in Correct Logic State
⎯
●
●
●
●
●
MIN
0.8
TYP
MAX
1.5
UNITS
V
V
V
μA
μA
5.7
6.2
30
45
7.0
50
80
Monitor Input (VM)
V
MT120
12V, 5% Reset Threshold
12V, 10% Reset Threshold
12V, 15% Reset Threshold
5V, 5% Reset Threshold
5V, 10% Reset Threshold
5V, 15% Reset Threshold
3.3V, 5% Reset Threshold
3.3V, 10% Reset Threshold
3.3V, 15% Reset Threshold
2.5V, 5% Reset Threshold
2.5V, 10% Reset Threshold
2.5V, 15% Reset Threshold
1.8V, 5% Reset Threshold
1.8V, 10% Reset Threshold
1.8V, 15% Reset Threshold
1.5V, 5% Reset Threshold
1.5V, 10% Reset Threshold
1.5V, 15% Reset Threshold
1.2V, 5% Reset Threshold
1.2V, 10% Reset Threshold
1.2V, 15% Reset Threshold
1V, 5% Reset Threshold
1V, 10% Reset Threshold
1V, 15% Reset Threshold
ADJ (0.5V), 5% Reset Threshold
ADJ (0.5V), 10% Reset Threshold
ADJ (0.5V), 15% Reset Threshold
VM Input Impedance (Note 4)
ADJ Input Current
Low Level Input Voltage
High Level Input Voltage
Pin Voltage when Open
Allowable Leakage in Open State
Pin Input Current
RT Pull Up Current
RT Pull Down Current
Internal RT V
CC
Detect Current
RT Internal Timer Threshold
V
TPIN
= 0V, V
CC
V
RT
= 0.25V
V
RT
= 1.1V
V
RT
= V
CC
V
RT
Rising, Referenced to V
CC
I = 0μA
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
11.04
10.44
9.84
4.600
4.350
4.100
3.036
2.871
2.706
2.300
2.175
2.050
1.656
1.566
1.476
1.380
1.305
1.230
1.104
1.044
0.984
0.920
0.870
0.820
460.0
435.0
410.0
0.5
11.22
10.62
10.02
4.675
4.425
4.175
3.086
2.921
2.756
2.338
2.213
2.088
1.683
1.593
1.503
1.403
1.328
1.253
1.122
1.062
1.002
0.935
0.885
0.835
467.5
442.5
417.5
11.40
10.80
10.20
4.750
4.500
4.250
3.135
2.970
2.805
2.375
2.250
2.125
1.710
1.620
1.530
1.425
1.350
1.275
1.140
1.080
1.020
0.950
0.900
0.850
475.0
450.0
425.0
8
±15
0.5
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
mV
mV
mV
MΩ
nA
V
V
V
V
MT50
V
MT33
V
MT25
V
MT18
V
MT15
V
MT12
V
MT10
V
MTADJ
R
VM
I
VM(ADJ)
V
TPIN, LOW
V
TPIN, HIGH
V
TPIN, Z
I
TPIN, Z
I
TPIN, H/L
I
RT(UP)
I
RT(DOWN)
I
RT(INT)
V
RT(INT, LH)
Fixed Threshold Modes
VM = 0.5V
●
●
Three-State Inputs (SEL1, SEL2), (TOL, LTC2917)
●
●
1.4
0.9
±5
±20
–2
2
–100
–3
3
1
–160
–4
4
8
–300
μA
μA
μA
μA
μA
mV
29178f
Reset Timer Control (RT)
●
●
●
●
4
LTC2917/LTC2918
ELECTRICAL CHARACTERISTICS
SYMBOL
Reset Output (
⎯
R
⎯
S
⎯
T)
t
RST(INT)
t
RST(EXT)
t
UV
V
OL
Internal Reset Timeout Period
Adjustable Reset Timeout Period
VM Undervoltage Detect to
⎯
R
⎯
S
⎯
T
Asserted
Output Voltage Low
⎯
R
⎯
S
⎯
T
V
RT
= V
CC
C
RT
= 2.2nF
VM Less Than Reset Threshold
V
MTX
by More Than 5%
V
CC
= 3.3V, I
RST
= 2.5mA
V
CC
= 1V, I
RST
= 100μA
V
CC
= 0.8V, I
RST
= 15μA
⎯
R
⎯
S
⎯
T = V
CC
V
WT
= 0.25V
V
WT
= 1.1V
V
WT
Rising, Referenced to V
CC
V
WT
= V
CC
V
WT
= 0V
V
WT
= V
CC
B Versions, V
WT
= V
CC
C
WT
= 2.2nF
B Versions, C
WT
= 2.2nF
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 2.5V, unless otherwise noted. (Note 2)
PARAMETER
CONDITIONS
MIN
150
16
10
TYP
200
20
80
0.15
0.15
0.05
MAX
260
25
150
0.4
0.3
0.2
±1
–2
2
–100
–3
3
–160
1
–3.5
1.3
37.5
130
1.6
50
160
t
WDU(EXT)
/32
0.4
1.1
400
±1
0.2 • V
CC
0.8 • V
CC
50
250
100
150
2
62.5
200
–4
4
–300
8
UNITS
ms
ms
μs
V
V
V
μA
μA
μA
mV
μA
μA
s
ms
ms
ms
V
V
ns
μA
V
V
kΩ
ns
I
OH(RST)
I
WT(UP)
I
WT(DOWN)
V
WT(INT, LH)
I
WT(INT)
I
WT(DIS)
t
WDU(INT)
t
WDL(INT)
t
WDU(EXT)
t
WDL(EXT)
V
IL(WDI)
V
IH(WDI)
t
PW(WDI)
⎯
R
⎯
S
⎯
T Output Voltage High Leakage
WT Pull Up Current
WT Pull Down Current
WT Internal Timer Threshold
Internal WT V
CC
Detect Current
Watchdog Disable Hold Current
Internal Watchdog Upper Boundary
Internal Watchdog Lower Boundary
(Note 5)
External Watchdog Upper Boundary
External Watchdog Lower Boundary
(Note 5)
Input Low Voltage
Input High Voltage
Input Pulsewidth
WDI Leakage Current
Watchdog Timer Control (WT)
●
●
●
●
Watchdog Input (WDI)
Manual Reset Input (LTC2918)
V
IL(MR)
V
IH(MR)
R
PU
t
PW(MR)
Input Low Voltage
Input High Voltage
Pull Up Resistance
Pulsewidth
●
●
●
●
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 6.2V shunt regulator, a low impedance supply
which exceeds 5.7V may exceed the rated terminal current. Operation
from higher voltage supplies requires a series dropping resistor. See
Applications Information.
Note 4:
Input impedance is dependent on the configuration of the SEL
pins.
Note 5:
In the LTC2917-B/LTC2918-B, edges must occur on WDI with a
period between the lower and upper boundary or
⎯
R
⎯
S
⎯
T is invoked. For the
LTC2917-A/LTC2918-A, the edges must simply occur before the upper
boundary. See Applications Information.
29178f
5
嵌入式系统
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