LTC2901-4IGN#TRPBF [Linear]
LTC2901 - Programmable Quad Supply Monitor with Adjustable Reset and Watchdog Timers; Package: SSOP; Pins: 16; Temperature Range: -40°C to 85°C;型号: | LTC2901-4IGN#TRPBF |
厂家: | Linear |
描述: | LTC2901 - Programmable Quad Supply Monitor with Adjustable Reset and Watchdog Timers; Package: SSOP; Pins: 16; Temperature Range: -40°C to 85°C 光电二极管 |
文件: | 总16页 (文件大小:185K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LTC2901
Programmable Quad Supply
Monitor with Adjustable Reset
and Watchdog Timers
U
FEATURES
DESCRIPTIO
The LTC®2901 is a programmable supply monitor for
systemswithuptofoursupplyvoltages. Oneof16preset
or adjustable voltage monitor combinations can be se-
lected using an external resistor divider connected to the
program pin. The preset voltage thresholds are accurate
to 1.5% over temperature. All four voltage comparator
outputs are connected to separate pins for individual
supply monitoring.
■
Simultaneously Monitors Four Supplies
16 User Selectable Combinations of 5V, 3.3V, 3V,
■
2.5V, 1.8V, 1.5V and/or Adj Voltage Thresholds
Guaranteed Threshold Accuracy: 1.5% of
■
Monitored Voltage Over Temperature
Selectable Supply Tolerance: 5% and 10% Below
■
Monitored Voltage (LTC2901-3/LTC2901-4)
Low Supply Current: 43μA Typ
Adjustable Reset Time
Adjustable Watchdog Time
Open-Drain RST Output (LTC2901-1/LTC2901-3)
Push-Pull RST Output (LTC2901-2/LTC2901-4)
Individual Nondelayed Monitor Output for Each Supply
■
■
The reset and watchdog delay times are adjustable using
externalcapacitors.Tightvoltagethresholdaccuracyand
glitch immunity ensure reliable reset operation without
falsetriggering.TheRSToutputisguaranteedtobeinthe
correct state for VCC down to 1V. The LTC2901-1/
LTC2901-3 features an open-drain RST output, while the
LTC2901-2/LTC2901-4 has a push-pull RST output.
■
■
■
■
■
Power Supply Glitch Immunity
Guaranteed RST for VCC ≥ 1V
■
■
16-Lead Narrow USSOP Package
The 43μA supply current makes the LTC2901 ideal for
power conscious systems and it may be configured to
monitor less than four inputs. The parts are available in
the 16-lead narrow SSOP package.
APPLICATIO S
■
Desktop and Notebook Computers
Multivoltage Systems
Telecom Equipment
Portable Battery-Powered Equipment
■
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Patent Pending.
■
■
■
Network Servers
U
TYPICAL APPLICATIO
Quadruple Supply Monitor (5V, 3.3V, 2.5V, 1.8V)
10% Undervoltage Monitoring, Watchdog Asserts RST
Quadruple Supply Monitor (5V, 3.3V, 2.5V, 1.8V)
5V
5V
3.3V
3.3V
DC/DC
CONVERTER
SYSTEM
LOGIC
DC/DC
CONVERTER
SYSTEM
LOGIC
2.5V
1.8V
2.5V
1.8V
R3
10k
R3
10k
POWER
GOOD
POWER
GOOD
V3
V4
V3
V4
V1
V2
V
V1
V2
V
COMP1
COMP2
COMP3
COMP4
WDI
COMP1
COMP2
COMP3
COMP4
WDI
LTC2901-2
LTC2901-4
C2
C2
0.1μF
0.1μF
C1
C1
0.1μF
REF
REF
0.1μF
WDO
TOL
5V
R1
59k
1%
R1
59k
1%
V
PG
V
PG
RST
RST
2901 TA01
2901 TA01b
GND CRT
CWT
GND CRT
CWT
R2
40.2k
1%
R2
40.2k
1%
t
t
= 216ms
= 940ms
t
t
= 216ms
= 940ms
RST
WD
RST
WD
C
RT
47nF
C
WT
47nF
C
C
WT
47nF
RT
47nF
2901fb
1
LTC2901
ABSOLUTE AXI U RATI GS (Notes 1, 2, 3)
W W
U W
V1, V2, V3, V4, VPG ..................................... –0.3V to 7V
RST (LTC2901-1/LTC2901-3) ..................... –0.3V to 7V
RST (LTC2901-2/LTC2901-4) ....... –0.3V to (V2 + 0.3V)
COMPX ....................................................... –0.3V to 7V
CWT, WDI, WDO ......................................... –0.3V to 7V
VREF, CRT, TOL ............................ –0.3V to (VCC + 0.3V)
Reference Load Current (IVREF) ............................ 1mA
V4 Input Current (–ADJ Mode)............................. –1mA
Operating Temperature Range
LTC2901-1C/LTC2901-2C/
LTC2901-3C/LTC2901-4C ....................... 0°C to 70°C
LTC2901-1I/LTC2901-2I/
LTC2901-3I/LTC2901-4I .................... –40°C to 85°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
U W
U
PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
ORDER PART
TOP VIEW
TOP VIEW
NUMBER
COMP3
COMP1
V3
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
COMP2
COMP4
V2
COMP3
COMP1
V3
1
2
3
4
5
6
7
8
16 COMP2
15 COMP4
14 V2
LTC2901-1CGN
LTC2901-2CGN
LTC2901-1IGN
LTC2901-2IGN
LTC2901-3CGN
LTC2901-4CGN
LTC2901-3IGN
LTC2901-4IGN
V1
V4
V1
13 V4
CRT
V
REF
CRT
12
11
V
REF
V
PG
RST
V
RST
PG
GN16 PART MARKING
GN16 PART MARKING
WDO
WDI
GND
CWT
TOL
10 GND
CWT
WDI
9
29013
29014
29013I
29014I
29011
29012
29011I
29012I
GN PACKAGE
16-LEAD PLASTIC SSOP
GN PACKAGE
16-LEAD PLASTIC SSOP
TJMAX = 125°C, θJA = 110°C/W
TJMAX = 125°C, θJA = 110°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/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise noted. (Notes 3, 4)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
V
V
V
V
V
V
5V, 5% Reset Threshold
5V, 10% Reset Threshold
V1 Input Threshold
●
●
4.600
4.350
4.675
4.425
4.750
4.500
V
V
RT50
RT33
RT30
RT25
RT18
RT15
RTA
3.3V, 5% Reset Threshold
3.3V, 10% Reset Threshold
V1, V2 Input Threshold
V2 Input Threshold
●
●
3.036
2.871
3.086
2.921
3.135
2.970
V
V
3V, 5% Reset Threshold
3V, 10% Reset Threshold
●
●
2.760
2.610
2.805
2.655
2.850
2.700
V
V
2.5V, 5% Reset Threshold
2.5V, 10% Reset Threshold
V2, V3 Input Threshold
V3, V4 Input Threshold
V3, V4 Input Threshold
V3, V4 Input Threshold
●
●
2.300
2.175
2.338
2.213
2.375
2.250
V
V
1.8V, 5% Reset Threshold
1.8V, 10% Reset Threshold
●
●
1.656
1.566
1.683
1.593
1.710
1.620
V
V
1.5V, 5% Reset Threshold
1.5V, 10% Reset Threshold
●
●
1.380
1.305
1.403
1.328
1.425
1.350
V
V
ADJ, 5% Reset Threshold
ADJ, 10% Reset Threshold
●
●
0.492
0.466
0.500
0.473
0.508
0.481
V
V
V
V
–ADJ Reset Threshold
V4 Input Threshold
●
●
–18
0
18
1
mV
V
RTAN
CC
Minimum Internal Operating Voltage
RST, COMPX in Correct Logic State;
V
Rising Prior to Program
CC
2901fb
2
LTC2901
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise noted. (Notes 3, 4)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
2.42
2.32
UNITS
V
V
V
Minimum Required for Programming
Minimum Required for Comparators
Reference Voltage
V
V
V
Rising
●
●
V
V
CCMINP
CCMINC
REF
CC
CC
CC
Falling
≥ 2.3V, I
T0L Low
T0L High
= 1mA, C ≤ 1000pF
REF
VREF
●
●
1.192
1.128
1.210
1.146
1.228
1.163
V
V
V
Programming Voltage Range
V
V
≥ V
●
●
●
●
0
V
V
nA
μA
μA
μA
nA
PG
VPG
V1
CC
PG
CCMINP
REF
I
I
I
I
V
Input Current
= V
20
75
2
PG
REF
V1 Input Current
V2 Input Current
V3 Input Current
V1 = 5V, I
V2 = 3.3V
V3 = 2.5V
= 12μA, (Note 5)
43
0.8
VREF
V2
●
●
0.52
1.2
15
V3
V3 = 0.55V (ADJ Mode)
–15
I
V4 Input Current
V4 = 1.8V
V4 = 0.55V (ADJ Mode)
V4 = –0.05V (–ADJ Mode)
●
●
●
0.34
0.8
15
15
μA
nA
nA
V4
–15
–15
I
I
t
t
CRT Pull-Up Current
CRT Pull-Down Current
Reset Time-Out Period
V
V
C
= 0V
●
●
●
–1.4
10
–2
20
7
–2.6
30
μA
μA
ms
μs
CRT(UP)
CRT(DN)
RST
CRT
CRT
= 1.3V
= 1500pF
5
9
RT
V Undervoltage Detect to RST or COMPX
X
V Less Than Reset Threshold V
by More Than 1%
150
UV
X
RTX
V
Output Voltage Low RST, COMPX
I
= 2.5mA; V1 = 3V, V2 = 3V;
SINK
●
0.15
0.4
V
OL
V3, V4 = 0V; V = 0V
PG
I
I
= 100μA; V2 = 1V; V1, V3, V4 = 0V
= 100μA; V1 = 1V; V2, V3, V4 = 0V
●
●
0.05
0.05
0.3
0.3
V
V
SINK
SINK
V
V
V
I
Output Voltage High RST, WDO, COMPX
(Note 6)
I
= 1μA
SOURCE
●
●
●
V2 – 1
V
V
V
OH
OL
OH
Output Voltage Low WDO
I
= 2.5mA; V1 = 5V, V2 = 3.3V;
0.15
0.4
SINK
V3, V4 = 1V; V = 0V
PG
Output Voltage High RST
(LTC2901-2/LTC2901-4) (Note 7)
I
= 200μA
0.8 • V2
SOURCE
CWT Pull-Up Current
V
V
C
V
V
V
V
= 0V
●
●
●
●
●
●
–1.4
10
–2
20
30
–2.6
30
μA
μA
ms
V
CWT(UP)
CWT(DN)
WD
CWT
CWT
I
t
CWT Pull-Down Current
Watchdog Time-Out Period
WDI Input Threshold High
WDI Input Threshold Low
WDI Input Pulse Width
WDI Pull-Up Current
= 1.3V
= 1500pF
= 3.3V to 5.5V
= 3.3V to 5.5V
= 3.3V
20
40
WT
CC
CC
CC
V
V
1.6
IH
IL
0.4
V
t
I
150
ns
μA
WP
WDI
= 0V
–10
0.1
WDI
Digital Input T0L
V
V
I
T0L Low Level Input Voltage
T0L High Level Input Voltage
T0L Input Current
V
V
= 3.3V to 5.5V
●
●
●
0.3V
CC
V
V
IL
CC
CC
= 3.3V to 5.5V
0.7V
CC
IH
TOL = V
1
μA
INTOL
CC
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 5: Under static no-fault conditions, V1 will necessarily supply quiescent
current. If at any time V2 is larger than V1, V2 must be capable of supplying
the quiescent current, programming (transient) current and reference load
current.
Note 2: All currents into pins are positive, all voltages are referenced to GND
unless otherwise noted.
Note 6: The output pins RST, WDO and COMPX have internal pull-ups to V2
of typically 6μA. However, external pull-up resistors may be used when faster
rise times are required or for V voltages greater than V2.
Note 3: The greater of V1, V2 is the internal supply voltage (V ).
OH
CC
Note 7: The push-pull RST output pin on the LTC2901-2/LTC2901-4 is
Note 4: 10% thresholds apply to the LTC2901-3/LTC2901-4 only when the
TOL pin is set to a logic high.
actively pulled up to V2.
2901fb
3
LTC2901
TEST CIRCUITS
RST, WDO
LTC2901-1
LTC2901-3
LTC2901-1
LTC2901-3
LTC2901-2
LTC2901-4
OR COMPX
RST
V1
V2
V3
V4
V1
V2
V3
V4
V1
V2
V3
V4
I
SINK
2.5mA,
RST, WDO
OR COMPX
I
I
SOURCE
1μA
SOURCE
200μA
100μA
2901 F01
2901 F02
2901 F03
Figure 1. RST, WDO, COMPX VOH Test
Figure 2. RST, WDO, COMPX VOL Test
Figure 3. Active Pull-Up RST VOH Test
W U
W
TI I G DIAGRA S
VX Monitor Timing
V
RTX
V
X
t
RST
t
UV
1.5V
RST
2901 TD
COMPX
Watchdog Timing (LTC2901-1/LTC2901-2)
t
RST
RST
WDI
t
WP
WDO
t
t
WD
WD
2901 TD2
Watchdog Timing (LTC2901-3/LTC2901-4)
t
t
RST
RST
RST
WDI
t
t
WD
WP
2901 TD3
2901fb
4
LTC2901
U W
TYPICAL PERFOR A CE CHARACTERISTICS
5V Threshold Voltage
vs Temperature
3.3V Threshold Voltage
vs Temperature
3V Threshold Voltage
vs Temperature
4.750
4.725
4.700
4.675
4.650
4.625
4.600
3.135
3.125
3.115
3.105
3.095
3.085
3.075
3.065
3.055
3.045
3.035
2.850
2.840
2.830
2.820
2.810
2.800
2.790
2.780
2.770
2.760
20
TEMPERATURE (°C)
–60 –40 –20
0
40 60 80 100
–60
20
TEMPERATURE (°C)
60 80
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
–40 –20
0
40
100
2901 G01
2901 G02
2901 G03
2.5V Threshold Voltage
vs Temperature
1.8V Threshold Voltage
vs Temperature
1.5V Threshold Voltage
vs Temperature
1.425
1.420
1.415
1.410
1.405
1.400
1.395
1.390
1.385
1.380
2.3750
2.3675
2.3600
2.3525
2.3450
2.3375
2.3300
2.3225
2.3150
2.3075
2.3000
1.710
1.705
1.700
1.695
1.690
1.685
1.680
1.675
1.670
1.665
1.660
1.655
40 60
–60 –40 –20
TEMPERATURE (°C)
80
0
20
80 100
–60
20
TEMPERATURE (°C)
60
–40 –20
0
40
100
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
2901 G05
2901 G06
2901 G04
ADJ Threshold Voltage
vs Temperature
–ADJ Threshold Voltage
vs Temperature
VREF vs Temperature
0.508
0.506
0.504
0.502
0.500
0.498
0.496
0.494
0.492
0.018
0.012
0.006
0
1.228
1.222
1.216
1.210
1.204
1.198
1.192
–0.006
–0.012
–0.018
–60
20
TEMPERATURE (°C)
60 80
–60
20
TEMPERATURE (°C)
60 80
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
–40 –20
0
40
100
–40 –20
0
40
100
2901 G07
2901 G08
2901 G23
2901fb
5
LTC2901
TYPICAL PERFOR A CE CHARACTERISTICS
U W
IV1 vs Temperature
IV2 vs Temperature
IV3 vs Temperature
100
90
80
70
60
50
40
30
20
10
0
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
V1 = 5V
V1 = 5V
V1 = 5V
V2 = 3.3V
V3 = 2.5V
V4 = 1.8V
V2 = 3.3V
V3 = 2.5V
V4 = 1.8V
V2 = 3.3V
V3 = 2.5V
V4 = 1.8V
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
80
–60
20
TEMPERATURE (°C)
60
–40 –20
0
40
100
2901 G09
2901 G10
2901 G11
Typical Transient Duration
vs Comparator Overdrive (V1, V2)
Typical Transient Duration
vs Comparator Overdrive (V3, V4)
IV4 vs Temperature
220
200
180
160
140
120
100
80
450
400
350
300
250
200
150
100
50
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
T
= 25°C
T
= 25°C
A
V1 = 5V
A
V2 = 3.3V
V3 = 2.5V
V4 = 1.8V
RESET OCCURS
ABOVE CURVE
RESET OCCURS
ABOVE CURVE
60
40
20
0
0
0.1
1
10
100
0.1
1
10
100
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V
)
RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V
)
RTX
RTX
2901 G13
2901 G22
2901 G12
RST Output Voltage
vs V1, VPG = 0V
Watchdog Time-Out Period
vs Temperature
Reset Time-Out Period
vs Temperature
8.9
38
5
4
3
2
1
0
C
= 1500pF
C
= 1500pF
RT
V1 = V2 = V3 = V4
10k PULL-UP FROM RST TO V1
WT
(SILVER MICA)
(SILVER MICA)
8.4
7.9
7.4
6.9
6.4
5.9
5.4
4.9
36
34
32
30
28
26
24
22
T
= 25°C
A
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
V1 (V)
–60 –40 –20
0
20 40 60 80 100
–60
60 80
–40 –20
20
TEMPERATURE (°C)
0
40
100
TEMPERATURE (°C)
2901 G14
2901 G15
2901 G16
2901fb
6
LTC2901
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Reset Time-Out Period
vs Capacitance
Watchdog Time-Out Period
vs Capacitance
RST, WDO, COMPX ISINK
vs Supply Voltage
100
10
10
1
10
9
8
7
6
5
4
3
2
1
0
T
= 25°C
T = 25°C
A
A
T
= 25°C
A
V
= 0.4V
OL
1
100m
10m
1m
100m
10m
1m
V
= 0.2V
OL
100μ
100n
100n
10p
100p
1n
10n
1μ
10p
100p
1n
10n
1μ
0
1
3
4
5
6
2
C
(FARAD)
C
(FARAD)
RT
V1 OR V2 (V)
WT
2901 G17
2901 G18
2901 G19
RST High Level Output Voltage
vs Output Source Current
(LTC2901-2/LTC2901-4)
COMPX and WDO Pull-Up
Current vs V2 (COMPX and
WDO Held at 0V)
RST, WDO, COMPX Voltage
Output Low vs Output Sink Current
20
18
16
14
12
10
8
3.0
2.5
2.0
1.5
1.0
0.5
0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
T
= 25°C
V1 = 5V
V2 = 3V
V3 = 2.5V
V4 = 1V
A
V2 = 3V
25°C
V1 = 5V
85°C
–40°C
–40°C
25°C
6
85°C
4
2
0
1
3
4
4.5
0
10 20 30 40 50 60 70 80 90
(mA)
0
0.5
1
1.5
(mA)
2
2.5
1.5
2
2.5
3.5
5
V2 (V)
I
I
SOURCE
SINK
2901 G24
2901 G20
2901 G21
COMPX Propagation Delay vs Input
Overdrive Above Threshold
RST Pull-Up Current vs V2
(LTC2901-1/LTC2901-3)
RST Pull-Up Current vs V2
(LTC2901-2/LTC2901-4)
6
5
4
3
2
1
0
250
200
150
100
50
20
18
16
14
12
10
8
T
= 25°C
T
= 25°C
A
A
T
= 25°C
A
V
RT33
V
V
6
RT33
RT30
V1, V2
V3, V4
V
V
RT30
RT25
4
V
RT25
2
0
0
1000
2
2.5
3
3.5
4
4.5
5
2
2.5
3
3.5
4
4.5
5
10
100
V2 (V)
V2 (V)
INPUT OVERDRIVE ABOVE THRESHOLD (mV)
2901 G25
2901 G26
2901 G27
2901fb
7
LTC2901
U
U
U
PI FU CTIO S
COMP3 (Pin 1): Comparator Output 3. Nondelayed, active
high logic output with weak pull-up to V2. Pulls high when
V3 is above reset threshold. May be pulled greater than V2
using external pull-up.
A rising or falling edge on the WDI pin clears the voltage
on the CWT capacitor, preventing WDO from going low.
When disabling the watchdog function, tie CWT to GND.
For the LTC2901-3/LTC2901-4, a watchdog time-out due
to a missed WDI edge issues an RST pulse on the RST pin
(the WDO function is merged into the RST function).
COMP1 (Pin 2): Comparator Output 1. Nondelayed, active
high logic output with weak pull-up to V2. Pulls high when
V1 is above reset threshold. May be pulled greater than V2
using external pull-up.
CWT (Pin 9): Watchdog Time-Out Programming Pin.
Attach a capacitor (CWT) between CWT and GND to set a
watchdog time-out period of 20ms/nF. Leaving the pin
open generates a minimum time-out of approximately
200μs. A 47nF capacitor will generate a 940ms watchdog
time-out period.
V3 (Pin 3): Voltage Input 3. Select from 2.5V, 1.8V, 1.5V
or ADJ. See Table 1 for details.
V1 (Pin 4): Voltage Input 1. Select from 5V or 3.3V. See
Table 1 for details. The greater of (V1, V2) is also VCC for
the device. Bypass this pin to ground with a 0.1μF (or
greater) capacitor.
GND (Pin 10): Ground.
V
PG (Pin 11): Voltage Threshold Combination Select In-
CRT (Pin 5): Reset Delay Time Programming Pin. Attach
anexternalcapacitor(CRT)toGNDtosetaresetdelaytime
of 4.6ms/nF. Leaving the pin open generates a minimum
delay of approximately 50μs. A 47nF capacitor will gener-
ate a 216ms reset delay time.
put. Connect to an external 1% resistive divider between
VREF andGNDtoselect1of16combinationsofpresetand/
or adjustable voltage thresholds (see Table 1). Do not
add capacitance on the VPG pin.
VREF (Pin 12): Buffered Reference Voltage. A 1.210V
nominal reference used for programming voltage (VPG)
and for the offset of negative adjustable applications. The
buffered reference can source and sink up to 1mA. The
reference can drive a bypass capacitor of up to 1000pF
without oscillation.
RST (Pin 6): Reset Logic Output. Active low with weak
pull-up to V2 (LTC2901-1/LTC2901-3) or active pull-up to
V2 (LTC2901-2/LTC2901-4). Pulls low when any voltage
input is below the reset threshold and held low for the
programmed delay time after all voltage inputs are above
threshold. May be pulled above V2 using an external pull-
up (LTC2901-1/LTC2901-3 only).
V4 (Pin 13): Voltage Input 4. Select from 1.8V, 1.5V, ADJ
or –ADJ. See Table 1 for details.
WDO (Pin 7): LTC2901-1/LTC2901-2 Watchdog Output.
Active low logic output with weak pull-up to V2. May be
pulled greater than V2 using external pull-up. The watch-
dog output pulls low if the watchdog timer is allowed to
time out and remains low until set high by the next WDI
transistion or anytime RST is low. The watchdog timer is
enabled when RST is high.
V2 (Pin 14): Voltage Input 2. Select from 3.3V, 3V or 2.5V.
See Table 1 for details. The greater of (V1, V2) is also VCC
for device. Bypass this pin to ground with a 0.1μF (or
greater) capacitor. All logic outputs (COMP1, COMP2,
COMP3, COMP4, RST, WDO) are weakly pulled up to V2
(LTC2901-1/LTC2901-3). RST is actively pulled up to V2
in the LTC2901-2/LTC2901-4.
T0L (Pin 7): LTC2901-3/LTC2901-4 Digital Input for Sup-
ply Tolerance Selection (5% or 10%). A logic low selects
5% thresholds; a logic high selects 10% thresholds.
COMP4 (Pin 15): Comparator Output 4. Nondelayed,
activehighlogicoutputwithweakpull-uptoV2. Pullshigh
when V4 is above reset threshold. May be pulled greater
than V2 using external pull-up.
WDI (Pin 8): Watchdog Input. A logic input whose rising
or falling edge must occur on this pin (while RST is high)
within the selected watchdog time-out period, prohibiting
a high-to-low transition on the WDO pin (LTC2901-1/
LTC2901-2). The watchdog time-out period is set by the
value of the capacitor that is attached to the CWT pin.
COMP2 (Pin 16): Comparator Output 2. Nondelayed,
activehighlogicoutputwithweakpull-uptoV2. Pullshigh
when V2 is above reset threshold. May be pulled greater
than V2 using external pull-up.
2901fb
8
LTC2901
W
BLOCK DIAGRA
LTC2901-1/LTC2901-2
V1
V2
V2
V2
V2
POWER
DETECT
V
CC
6μA
6μA
6μA
6μA
COMP1
–
V2
2
+
–
+
V1
4
V2
14
COMP2
16
RESISTIVE
DIVIDER
V3
MATRIX
–
+
3
V4
13
GND
10
COMP3
1
–
+
V
PG
A/D
11
BUFFER
V
REF
BANDGAP
REFERENCE
12
COMP4
15
ADJUSTABLE
RESET PULSE
GENERATOR
V
CC
LTC2901-1
V2
2μA
6μA
22μA
RST
6
LTC2901-2
V2
10μA
TRANSITION
DETECT
WATCHDOG
TIMER
V
CC
RST
6
V
CC
V2
2μA
6μA
22μA
WDO
7
5
CRT
8
WDI
C
RT
9
CWT
C
WT
2901 DB-1
2901fb
9
LTC2901
W
BLOCK DIAGRA
LTC2901-3/LTC2901-4
V1
V2
V2
V2
V2
POWER
DETECT
V
CC
6μA
6μA
6μA
6μA
COMP1
2
–
V2
+
–
+
V1
4
V2
14
COMP2
16
RESISTIVE
DIVIDER
V3
MATRIX
–
+
3
V4
13
GND
10
COMP3
1
–
+
V
PG
A/D
11
BUFFER
V
REF
BANDGAP
REFERENCE
12
COMP4
15
ADJUSTABLE
RESET PULSE
GENERATOR
BUFFER GAIN
ADJUST
V
CC
TOL
7
LTC2901-3
V2
2μA
6μA
22μA
RST
6
LTC2901-4
V2
10μA
TRANSITION
DETECT
WATCHDOG
TIMER
V
CC
RST
6
V
CC
2μA
22μA
5
CRT
8
WDI
C
RT
9
CWT
C
WT
2901 DB-1
2901fb
10
LTC2901
W U U
U
APPLICATIO S I FOR ATIO
R1
1%
Power-Up
LTC2901
12
11
10
V
REF
The greater of V1, V2 is the internal supply voltage (VCC).
On power-up, VCC will power the drive circuits for the RST
andtheCOMPXpins.ThisensuresthattheRSTandCOMPX
outputs will be low as soon as V1 or V2 reaches 1V. The
RST and COMPX outputs will remain low until the part is
programmed.Afterprogramming,ifanyoneoftheVXinputs
isbelowitsprogrammedthreshold,RSTwillbealogiclow.
Once all the VX inputs rise above their thresholds, an inter-
nal timer is started and RST is released after the pro-
grammed delay time. If VCC < (V3 – 1) and VCC < 2.4V, the
V3 input impedance will be low (1kΩ typ).
V
PG
R2
GND
1%
2901 F04
Figure 4. Monitor Programming
150μs during which the voltage on the VPG pin is sampled
and the monitor is configured to the desired input combi-
nation.DonotaddcapacitancetotheVPG pin.Immediately
after programming, the comparators are enabled and
supply monitoring will begin.
Supply Monitoring
The LTC2901 is a low power, high accuracy program-
mablequadsupplymonitoringcircuitwithfournondelayed
monitor outputs, a common reset output and a watchdog
timer. Watchdog and reset timing are both adjustable
usingexternalcapacitors.Singlepinprogrammingselects
1 of 16 input voltage monitor combinations. All four
voltage inputs must be above predetermined thresholds
fortheresetnottobeinvoked. TheLTC2901willassertthe
reset and comparator outputs during power-up, power-
down and brownout conditions on any one of the voltage
inputs.
Monitor Programming
The LTC2901 input voltage combination is selected by
placing the recommended resistive divider from VREF to
GND and connecting the tap point to VPG, as shown in
Figure 4. Table 1 offers recommended 1% resistor values
forthevariousmodes. ThelastcolumninTable1specifies
optimum VPG/VREF ratios ( 0.01) to be used when pro-
gramming with a ratiometric DAC.
During power-up, once V1 or V2 reaches 2.4V max, the
monitor enters a programming period of approximately
The inverting inputs on the V3 and/or V4 comparators are
setto0.5Vwhenthepositiveadjustablemodesareselected
(Figure 5). The tap point on an external resistive divider,
connected between the positive voltage being sensed and
ground, is connected to the high impedance noninverting
inputs (V3, V4). The trip voltage is calculated from:
Table 1. Voltage Threshold Programming
V
PG
MODE V1 (V) V2 (V) V3 (V) V4 (V) R1 (kΩ) R2 (kΩ)
V
REF
0
1
5.0
5.0
3.3
3.3
3.3
5.0
5.0
5.0
5.0
5.0
3.3
3.3
3.3
5.0
5.0
5.0
3.3
3.3
2.5
2.5
2.5
3.3
3.3
3.3
3.0
3.0
2.5
2.5
2.5
3.3
3.3
3.0
ADJ
ADJ
ADJ
ADJ
1.5
2.5
2.5
2.5
2.5
ADJ
1.8
1.8
1.8
1.8
1.8
1.8
ADJ
–ADJ
ADJ
–ADJ
ADJ
ADJ
1.8
Open
93.1
86.6
78.7
71.5
66.5
59.0
53.6
47.5
40.2
34.8
28.0
22.1
16.2
9.53
Short
Short
9.53
16.2
22.1
28.0
34.8
40.2
47.5
53.6
59.0
66.5
71.5
78.7
86.6
93.1
Open
0.000
0.094
0.156
0.219
0.281
0.344
0.406
0.469
0.531
0.594
0.656
0.719
0.781
0.844
0.906
1.000
2
3
R3
R4
⎛
⎝
⎞
⎟
⎠
4
VTRIP = 0.5V 1+
⎜
5
6
Inthenegativeadjustablemode, thenoninvertinginputon
the V4 comparator is connected to ground (Figure 6). The
tap point on an external resistive divider, connected be-
tween the negative voltage being sensed and the VREF pin,
is connected to the high impedance inverting input (V4).
7
1.5
8
ADJ
ADJ
1.5
9
10
11
12
13
14
15
ADJ
–ADJ
–ADJ
ADJ
ADJ
V
REF provides the necessary level shift required to operate
at ground. The trip voltage is calculated from:
R3
R4
⎛
⎜
⎝
⎞
⎟
⎠
VTRIP = –VREF
; V = 1.210V Nominal
REF
2901fb
11
LTC2901
APPLICATIO S I FOR ATIO
W U U
U
V
TRIP
Table 2. Suggested 1% Resistor Values for the ADJ Inputs
LTC2901
V
(V)
V
(V)
TRIP
R3 (kΩ)
2150
1780
1400
1300
1020
845
R4 (kΩ)
100
100
100
100
100
100
100
100
100
100
100
100
100
100
R3
SUPPLY
1%
12
11.25
9.4
V3 OR V4
+
R4
1%
10
8
7.5
–
7.5
6
7
+
0.5V
5.6
–
5
4.725
3.055
2.82
2.325
1.685
1.410
1.120
0.933
0.840
2901 F05
3.3
3
511
464
Figure 5. Setting the Positive Adjustable Trip Point
2.5
1.8
1.5
1.2
1
365
12
237
LTC2901
V
REF
R4
1%
182
13 V4
124
–
R3
1%
86.6
68.1
+
0.9
V
TRIP
Table 3. Suggested 1% Resistor Values for the –ADJ Input
2901 F06
V
(V)
V
(V)
TRIP
R3 (kΩ)
187
R4 (kΩ)
121
SUPPLY
Figure 6. Setting the Negative Adjustable Trip Point
–2
–1.87
–4.64
–4.87
–9.31
–5
–5.2
–10
–12
464
121
In a negative adjustable application, the minimum value
forR4islimitedbythesourcingcapabilityofVREF ( 1mA).
With no other load on VREF, R4 (minimum) is:
487
121
931
121
–11.30
1130
121
1.21V ÷ 1mA = 1.21kΩ.
Tables 2 and 3 offer suggested 1% resistor values for
various adjustable applications.
(VCC < 2V typ), the part will reprogram once VCC rises
above 2.4V max.
Once the resistor divider is set in the 5% tolerance mode
(LTC2901-3/LTC2901-4), there is no need to change the
divider for the 10% mode because the internal and exter-
nal reference is scaled accordingly, moving the trip point
by –5%.
Monitor Output Rise and Fall Time Estimation
All of the outputs (RST, COMPX, WDO) have strong pull-
down capability. If the external load capacitance (CLOAD
)
for a particular output is known, output fall time (10% to
90%) is estimated using:
Although all four supply monitor comparators have built-
in glitch immunity, bypass capacitors on V1 and V2 are
recommended because the greater of V1 or V2 is also the
VCC for the device. Filter capacitors on the V3 and V4
inputs are allowed.
tFALL ≈ 2.2 • RPD • CLOAD
where RPD is the on-resistance of the internal pull-down
transistor. The typical performance curve (VOL vs ISINK
)
demonstrates that the pull-down current is somewhat
linear versus output voltage. Using the 25°C curve, RPD is
estimated to be approximately 40Ω. Assuming a 150pF
load capacitance, the fall time is about 13.2ns.
Power-Down
On power-down, once any of the VX inputs drop below
their threshold, RST and COMPX are held at a logic low.
A logic low of 0.4V is guaranteed until both V1 and V2
drop below 1V. If the bandgap reference becomes invalid
Although the outputs are considered to be “open-drain,”
theydohaveaweakpull-upcapability(seeCOMPXorRST
2901fb
12
LTC2901
W U U
APPLICATIO S I FOR ATIO
U
WDO high indefinitely. It is safe to leave the WDI pin
(Pin 8) unconnected because the weak internal pull-up
(10μA typ) will pull WDI high. Tying WDI to V1 or ground
is also allowed, but grounding the WDI pin will force the
pull-up current to be drawn continuously.
Pull-Up Current vs V2 curve). Output rise time (10% to
90%) is estimated using:
tRISE ≈ 2.2 • RPU • CLOAD
where RPU is the on-resistance of the pull-up transistor.
The on-resistance as a function of the V2 voltage at room
temperature is estimated using:
Selecting the Reset Timing Capacitor
6 •105
V2 – 1
The reset time-out period is adjustable in order to accom-
modate a variety of microprocessor applications. The
reset time-out period, tRST, is adjusted by connecting a
capacitor, CRT, between the CRT pin and ground. The
value of this capacitor is determined by:
RPU
=
Ω
with V2 = 3.3V, RPU is about 260k. Using 150pF for load
capacitance, the rise time is 86μs. If the output needs to
pull up faster and/or to a higher voltage, a smaller
external pull-up resistor may be used. Using a 10k pull-
up resistor, the rise time is reduced to 3.3μs for a 150pF
load capacitance.
CRT = tRST • 217 • 10–9
withCRT inFaradsandtRST inseconds. TheCRT valueper
millisecond of delay can also be expressed as CRT/ms =
217 (pF/ms).
The LTC2901-2 has an active pull-up to V2 on the RST
output. The typical performance curve (RST Pull-Up Cur-
rent vs V2 curve) demonstrates that the pull-up current is
somewhat linear versus the V2 voltage and RPU is esti-
mated to be approximately 625Ω. A 150pF load capaci-
tance makes the rise time about 206ns.
Leaving the CRT pin unconnected will generate a mini-
mum reset time-out of approximately 50μs. Maximum
reset time-out is limited by the largest available low
leakagecapacitor. Theaccuracyofthetime-outperiodwill
be affected by capacitor leakage (the nominal charging
current is 2μA) and capacitor tolerance. A low leakage
ceramic capacitor is recommended.
Watchdog Timer
ThewatchdogcircuittypicallymonitorsaμP’sactivity.The
μP is required to change the logic state of the WDI pin on
a periodic basis in order to clear the watchdog timer and
preventtheWDOpin(LTC2901-1/LTC2901-2)fromgoing
low. Whenever RST is low, the watchdog timer is cleared
and WDO is set high. The watchdog timer is started when
RSTpullshigh.SubsequentedgesreceivedontheWDIpin
will clear the watchdog timer. The timer will continue to
rununtilthewatchdogtimertimesout. Oncethewatchdog
timer times out, internal circuitry will bring the WDO pin
low. WDO will remain low and the watchdog timer will
remain cleared until the next edge is received on the WDI
pin or until RST goes low.
Selecting the Watchdog Timing Capacitor
The watchdog time-out period is adjustable and can be
optimized for software execution. The watchdog time-out
period, tWD, is adjusted by connecting a capacitor, CWT
between the CWT pin and ground. Given a specified
watchdog time-out period, the capacitor is determined by:
,
CWT = tWD • 50 • 10–9
with CWT in Farads and tWD in seconds. The CWT value per
millisecond of delay can also be expressed as CWT/ms =
50 (pF/ms).
Leaving the CWT pin unconnected will generate a mini-
mum watchdog time-out of approximately 200μs. Maxi-
mum time-out is limited by the largest available low
leakagecapacitor. Theaccuracyofthetime-outperiodwill
be affected by capacitor leakage (the nominal charging
current is 2μA) and capacitor tolerance. A low leakage
ceramic capacitor is recommended.
IntheLTC2901-3/LTC2901-4,thereisnoWDOpin.Instead,
the RST pin is pulled low for the programmed reset time-
outperiodwheneveraWDIedgeismissed.Inthismanner,
a full system reset can be issued after a watchdog failure.
Todisablethewatchdogtimer, simplygroundtheCWTpin
(Pin9).WithCWTheldatground,anyreseteventwillforce
2901fb
13
LTC2901
W U U
U
APPLICATIO S I FOR ATIO
Monitoring Power Supply Controller Activity
period. The WDO pin will go low indicating the low load
condition. The WDO pin will return high on the next pulse
to the gate of M1. The WDO pin will remain high if the load
is restored.
Figure 7 demonstrates how the LTC2901 can be used to
monitor switcher activity. The monitor is configured to
supervise 3.3V, 2.5V, 1.8V and one adjustable input.
Because 2.5V does not exist in this application, the V2
input is tied to the V1 (3.3V) input. The feedback voltage
on the LTC1772 (0.8V typ) is monitored with the adjust-
able input (V4). The RST pin will go high 216ms
(CRT = 47nF) after the 3.3V and 1.8V supplies and the
feedback voltage are above threshold. Individual input
status is available at the COMPX pins.
Ensuring Reset Valid for VCC Down to 0V
(LTC2901-2/LTC2901-4)
Some applications require the reset output (RST) to be
valid with VCC down to 0V. The LTC2901-2 is designed to
handle this requirement with the addition of an external
resistor from RST to ground. The resistor will provide a
path for stray charge and/or leakage currents, preventing
the RST output from floating to undetermined voltages
when connected to high impedance (such as CMOS logic
inputs). The resistor value should be small enough to
provide effective pull-down without excessively loading
the active pull-up circuitry. Too large a value may not pull
down well enough. A 100k resistor from RST to ground is
satisfactory for most applications.
While the voltage monitors can detect low voltage or
shorted inputs, the watchdog circuit can be used to detect
an open circuit to the primary load. With the CWT pin
unconnected, the watchdog time-out is approximately
200μs. At low load currents on the 1.8V supply, the
LTC1772 will go into Burst Mode® operation. With an
open-ciruit load, the duty cycle at the gate of M1 will drop,
and the pulse spacing will exceed the watchdog time-out
Burst Mode is a registered trademark of Linear Technology Corporation.
V
IN
3.3V
LTC2901-2
C1
R5
4
14
3
2
3.3V MONITOR
V1
COMP1
COMP2
COMP3
COMP4
RST
10μF
0.15Ω
16
1
10V
V2
LTC1772
PGATE
1
2
3
6
5
4
1.8V MONITOR
L1
10μH
V3
M1
I
TH
13
8
15
6
R6
V
OUT
FEEDBACK MONITOR
COMMON RESET OUT
LOW LOAD INDICATOR
V4
GND
V
IN
–
10k
1.8V
0.5A
+
C2
WDI
V
SENSE
C3
220pF
FB
D1
47μF
R3
12
11
10
7
6V
100k
V
WDO
REF
R1
28k
1%
5
V
CRT
PG
9
C1: TAIYO YUDEN CERAMIC LMK325BJ106K-T
C2: SANYO POSCAP 6TPA47M
D1: MOTOROLA MBRM120T3
L1: COILTRONICS UP1B-100
M1: Si3443DV
GND
CWT
R4
80.6k
R2
71.5k
1%
C
RT
47nF
R5: DALE 0.25W
2901 F07
Figure 7. Monitor Input, Output, Feedback Voltage and Low Load Conditions on DC/DC Controller
2901fb
14
LTC2901
U
TYPICAL APPLICATIO S
Quad Supply Monitor with Watchdog Timer Disabled
5V, 3V, 1.8V, 12V (ADJ)
5V, –5V Monitor with Watchdog Timer Disabled and Unused
V2, V3 Inputs Pulled Above Trip Thresholds
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
COMP3 COMP2
COMP1 COMP4
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
COMP3 COMP2
COMP1 COMP4
R3
2.15M
1%
R3
464k
1%
1.8V
5V
V3
V2
V4
3V
V3
V2
V4
LTC2901
V1
12V
5V
LTC2901
V1
–5V
V
TRIP
= 11.25V
CRT
RST
V
REF
V
TRIP
= –4.64V
CRT
RST
V
REF
SYSTEM
RESET
R4
100k
1%
V
PG
R1
16.2k
1%
R4
121k
1%
SYSTEM
RESET
V
PG
WDO
WDI
GND
CWT
WDO
WDI
GND
CWT
C
C
RT
RT
R2
86.6k
1%
2901 TA02
2901 TA03
Quad Supply Monitor with LED Undervoltage Indicators
5V, 3.3V, 2.5V, 1.5V
R
L1
1k
R
L3
1k
R
L2
1k
R
L4
1k
LED
LED
LED
LED
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
COMP3 COMP2
COMP1 COMP4
2.5V
3.3V
1.5V
V3
V2
V4
5V
LTC2901
V1
CRT
RST
V
REF
R1
SYSTEM RESET
WATCHDOG STATUS
WDI
V
PG
53.6k
1%
WDO
WDI
GND
CWT
R2
47.5k
1%
C
C
WT
RT
2901 TA04
Generate RESET Pulse Through Watchdog Timeout (LTC2901-1/LTC2901-2)
1
2
3
4
5
6
7
8
16
COMP3 COMP2
t
15
RST
COMP1 COMP4
14
ADJ
V3
V2
V4
3.3V
RST
WDO
WDI
13
12
11
10
9
5V
LTC2901
V1
10k
CRT
RST
V
REF
RST
V
PG
WDO
WDI
GND
CWT
~20μs
WDI
C
C
WT
RT
2901 TA06
t
WD
2901fb
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
15
LTC2901
U
TYPICAL APPLICATIO
Monitor Seven Supplies (12V, 5V, 3.3V, 2.5V, 1.8V, –2V, –5.2V) with
Sequenced Reset and AC Present Indication
5V
12V
10k
10k
5V
0.1μF
AC/DC
DC/DC
3.3V
2.5V
1.8V
–2V
–5.2V
LTC2901-1
LTC2901-1
4
14
3
2
4
14
3
2
5V MONITOR
V1
COMP1
COMP2
COMP3
COMP4
RST
V1
COMP1
COMP2
COMP3
COMP4
RST
CONVERTERS
16
1
16
1
0.1μF
3.3V
1.8V
3.3V MONITOR
1.8V MONITOR
–5.2V MONITOR
2.5V MONITOR
12V MONITOR
–2V MONITOR
COMMON RESET OUT
AC PRESENT
2.5V
V2
V2
V3
V3
13
8
15
6
13
8
15
6
V4
V4
WDI
WDI
120V AC
12
11
10
7
12
11
10
7
12V
V
V
WDO
V
V
WDO
REF
PG
REF
PG
LOW
VOLTAGE
SECONDARY
5
5
121k 16.2k
1% 1%
2.15M
1%
121k 78.7k
1% 1%
CRT
CRT
9
9
GND
CWT
GND
CWT
487k 86.6k
1% 1%
100k
1%
187k 22.1k
1% 1%
C
C
C
RT2
47nF
RT1
WT
680pF
100k
47nF
2901 TA05
–5.2V
–2V
1N4148
1N4148
100k
t
t
+ t
= 432ms
Q1
2N3904
RST1 RST2
WD
= 13.6ms
U
PACKAGE DESCRIPTIO
GN Package
16-Lead Plastic SSOP (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1641)
.189 – .196*
(4.801 – 4.978)
.009
(0.229)
REF
.015 .004
(0.38 0.10)
.045 .005
.150 – .165
16 15 14 13 12 11 10 9
× 45°
.0532 – .0688
(1.35 – 1.75)
.004 – .0098
(0.102 – 0.249)
.007 – .0098
(0.178 – 0.249)
0° – 8° TYP
.229 – .244
(5.817 – 6.198)
.150 – .157**
(3.810 – 3.988)
.016 – .050
(0.406 – 1.270)
.0250
(0.635)
BSC
.008 – .012
(0.203 – 0.305)
TYP
.254 MIN
NOTE:
1. CONTROLLING DIMENSION: INCHES
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
INCHES
2. DIMENSIONS ARE IN
(MILLIMETERS)
GN16 (SSOP) 0204
.0250
BSC
3. DRAWING NOT TO SCALE
4
5
1
2
3
6
7
8
.0165 .0015
RECOMMENDED SOLDER PAD LAYOUT
RELATED PARTS
PART NUMBER
LTC694-3.3
DESCRIPTION
3.3V Supply Monitor, Watchdog Timer and Battery Backup
COMMENTS
2.9V Threshold
LTC1326
Micropower Precision Triple Supply Monitor for 5V, 3.3V and ADJ
Micropower Triple Supply Monitor for 2.5V, 3.3V and ADJ
Micropower Triple Supply Monitors with Open-Drain Reset
4.725V, 3.118V, 1V Thresholds ( 0.75%)
Adjustable RESET and Watchdog Time-Outs
Individual Monitor Outputs in MSOP
5-Lead SOT-23 Package
LTC1726-2.5
LTC1727-2.5/LTC1727-5
LTC1728-1.8/LTC1728-3.3 Micropower Triple Supply Monitor with Open-Drain Reset
LTC2900
LTC2902
LTC2903
Programmable Quad Supply Monitor
Adjustable Reset Timer, 10-Lead MSOP
and 3mm × 3mm 10-Lead DFN
Programmable Quad Supply Monitor
Adjustable Reset Timer, Supply Tolerance and
Margining Functions, 16-Lead Narrow SSOP
Precision Quad Supply Monitor in 6-Lead SOT-23
Precision Dual Supply Monitors
A Variety of Factory Trimmed Voltage Combinations
Pin Selectable Thresholds
LTC2904/LTC2905
LTC2906/LTC2907
LTC2908
Precision Six Supply Monitor
8-Lead SOT-23 and DFN Packages
2901fb
LT 0807 REV B • PRINTED IN USA
16 LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2002
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