1
LTC2901
2901fb
Programmable Quad Supply
Monitor with Adjustable Reset
and Watchdog Timers
■
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
■
Power Supply Glitch Immunity
■
Guaranteed RST for V
CC
≥ 1V
■
16-Lead Narrow SSOP Package
The LTC
®
2901 is a programmable supply monitor for
systems with up to four supply voltages. One of 16 preset
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.
The reset and watchdog delay times are adjustable using
external capacitors. Tight voltage threshold accuracy and
glitch immunity ensure reliable reset operation without
false triggering. The RST output is guaranteed to be in the
correct state for V
CC
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.
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.
Quadruple Supply Monitor (5V, 3.3V, 2.5V, 1.8V)
■
Desktop and Notebook Computers
■
Multivoltage Systems
■
Telecom Equipment
■
Portable Battery-Powered Equipment
■
Network Servers
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
V1
V2
VREF
VPG
COMP1
COMP2
COMP3
COMP4
WDI
WDO
RST
GND
R1
59k
1%
R3
10k POWER
GOOD
R2
40.2k
1%
CWT
47nF
CRT
47nF
C2
0.1μF
C1
0.1μF
V4V3
LTC2901-2
CWTCRT
tRST = 216ms
tWD = 940ms
2901 TA01
DC/DC
CONVERTER
1.8V
2.5V
3.3V
5V
SYSTEM
LOGIC
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
Quadruple Supply Monitor (5V, 3.3V, 2.5V, 1.8V)
10% Undervoltage Monitoring, Watchdog Asserts RST
V1
V2
VREF
VPG
COMP1
COMP2
COMP3
COMP4
WDI
TOL
RST
GND
R1
59k
1%
R3
10k POWER
GOOD
R2
40.2k
1%
CWT
47nF
5V
CRT
47nF
C2
0.1μF
C1
0.1μF
V4V3
LTC2901-4
CWTCRT
tRST = 216ms
tWD = 940ms
2901 TA01b
DC/DC
CONVERTER
1.8V
2.5V
3.3V
5V
SYSTEM
LOGIC
Patent Pending.
2
LTC2901
2901fb
V1, V2, V3, V4, V
PG
..................................... –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
V
REF
, CRT, TOL ............................ –0.3V to (V
CC
+ 0.3V)
Reference Load Current (I
VREF
) ............................ ±1mA
V4 Input Current (–ADJ Mode)............................. –1mA
ABSOLUTE AXI U RATI GS
WWWU
(Notes 1, 2, 3)
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
ORDER PART
NUMBER
GN16 PART MARKING
29011
29012
29011I
29012I
T
JMAX
= 125°C, θ
JA
= 110°C/W
LTC2901-1CGN
LTC2901-2CGN
LTC2901-1IGN
LTC2901-2IGN
PACKAGE/ORDER I FOR ATIO
UU
W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ORDER PART
NUMBER
GN16 PART MARKING
29013
29014
29013I
29014I
LTC2901-3CGN
LTC2901-4CGN
LTC2901-3IGN
LTC2901-4IGN
GN PACKAGE
16-LEAD PLASTIC SSOP
1
2
3
4
5
6
7
8
TOP VIEW
16
15
14
13
12
11
10
9
COMP3
COMP1
V3
V1
CRT
RST
WDO
WDI
COMP2
COMP4
V2
V4
V
REF
V
PG
GND
CWT
GN PACKAGE
16-LEAD PLASTIC SSOP
1
2
3
4
5
6
7
8
TOP VIEW
16
15
14
13
12
11
10
9
COMP3
COMP1
V3
V1
CRT
RST
TOL
WDI
COMP2
COMP4
V2
V4
V
REF
V
PG
GND
CWT
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
RT50
5V, 5% Reset Threshold V1 Input Threshold ●4.600 4.675 4.750 V
5V, 10% Reset Threshold ●4.350 4.425 4.500 V
V
RT33
3.3V, 5% Reset Threshold V1, V2 Input Threshold ●3.036 3.086 3.135 V
3.3V, 10% Reset Threshold ●2.871 2.921 2.970 V
V
RT30
3V, 5% Reset Threshold V2 Input Threshold ●2.760 2.805 2.850 V
3V, 10% Reset Threshold ●2.610 2.655 2.700 V
V
RT25
2.5V, 5% Reset Threshold V2, V3 Input Threshold ●2.300 2.338 2.375 V
2.5V, 10% Reset Threshold ●2.175 2.213 2.250 V
V
RT18
1.8V, 5% Reset Threshold V3, V4 Input Threshold ●1.656 1.683 1.710 V
1.8V, 10% Reset Threshold ●1.566 1.593 1.620 V
V
RT15
1.5V, 5% Reset Threshold V3, V4 Input Threshold ●1.380 1.403 1.425 V
1.5V, 10% Reset Threshold ●1.305 1.328 1.350 V
V
RTA
ADJ, 5% Reset Threshold V3, V4 Input Threshold ●0.492 0.500 0.508 V
ADJ, 10% Reset Threshold ●0.466 0.473 0.481 V
V
RTAN
–ADJ Reset Threshold V4 Input Threshold ●–18 0 18 mV
V
CC
Minimum Internal Operating Voltage RST, COMPX in Correct Logic State; ●1V
V
CC
Rising Prior to Program
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)
ELECTRICAL CHARACTERISTICS
T
JMAX
= 125°C, θ
JA
= 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/
3
LTC2901
2901fb
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)
ELECTRICAL CHARACTERISTICS
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 greater of V1, V2 is the internal supply voltage (V
CC
).
Note 4: 10% thresholds apply to the LTC2901-3/LTC2901-4 only when the
TOL pin is set to a logic high.
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 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
OH
voltages greater than V2.
Note 7: The push-pull RST output pin on the LTC2901-2/LTC2901-4 is
actively
pulled up to V2.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
CCMINP
Minimum Required for Programming V
CC
Rising ●2.42 V
V
CCMINC
Minimum Required for Comparators V
CC
Falling ●2.32 V
V
REF
Reference Voltage V
CC
≥ 2.3V, I
VREF
= ±1mA, C
REF
≤ 1000pF
T0L Low ●1.192 1.210 1.228 V
T0L High ●1.128 1.146 1.163 V
V
PG
Programming Voltage Range V
CC
≥ V
CCMINP
●0V
REF
V
I
VPG
V
PG
Input Current V
PG
= V
REF
●±20 nA
I
V1
V1 Input Current V1 = 5V, I
VREF
= 12μA, (Note 5) ●43 75 μA
I
V2
V2 Input Current V2 = 3.3V ●0.8 2 μA
I
V3
V3 Input Current V3 = 2.5V ●0.52 1.2 μA
V3 = 0.55V (ADJ Mode) ●–15 15 nA
I
V4
V4 Input Current V4 = 1.8V ●0.34 0.8 μA
V4 = 0.55V (ADJ Mode) ●–15 15 nA
V4 = –0.05V (–ADJ Mode) ●–15 15 nA
I
CRT(UP)
CRT Pull-Up Current V
CRT
= 0V ●–1.4 –2 –2.6 μA
I
CRT(DN)
CRT Pull-Down Current V
CRT
= 1.3V ●10 20 30 μA
t
RST
Reset Time-Out Period C
RT
= 1500pF ●579 ms
t
UV
V
X
Undervoltage Detect to RST or COMPX V
X
Less Than Reset Threshold V
RTX
150 μs
by More Than 1%
V
OL
Output Voltage Low RST, COMPX I
SINK
= 2.5mA; V1 = 3V, V2 = 3V; ●0.15 0.4 V
V3, V4 = 0V; V
PG
= 0V
I
SINK
= 100μA; V2 = 1V; V1, V3, V4 = 0V ●0.05 0.3 V
I
SINK
= 100μA; V1 = 1V; V2, V3, V4 = 0V ●0.05 0.3 V
V
OH
Output Voltage High RST, WDO, COMPX I
SOURCE
= 1μA●V2 – 1 V
(Note 6)
V
OL
Output Voltage Low WDO I
SINK
= 2.5mA; V1 = 5V, V2 = 3.3V; ●0.15 0.4 V
V3, V4 = 1V; V
PG
= 0V
V
OH
Output Voltage High RST I
SOURCE
= 200μA●0.8 • V2 V
(LTC2901-2/LTC2901-4) (Note 7)
I
CWT(UP)
CWT Pull-Up Current V
CWT
= 0V ●–1.4 –2 –2.6 μA
I
CWT(DN)
CWT Pull-Down Current V
CWT
= 1.3V ●10 20 30 μA
t
WD
Watchdog Time-Out Period C
WT
= 1500pF ●20 30 40 ms
V
IH
WDI Input Threshold High V
CC
= 3.3V to 5.5V ●1.6 V
V
IL
WDI Input Threshold Low V
CC
= 3.3V to 5.5V ●0.4 V
t
WP
WDI Input Pulse Width V
CC
= 3.3V ●150 ns
I
WDI
WDI Pull-Up Current V
WDI
= 0V –10 μA
Digital Input T0L
V
IL
T0L Low Level Input Voltage V
CC
= 3.3V to 5.5V ●0.3V
CC
V
V
IH
T0L High Level Input Voltage V
CC
= 3.3V to 5.5V ●0.7V
CC
V
I
INTOL
T0L Input Current TOL = V
CC
●±0.1 ±1μA
4
LTC2901
2901fb
TI I G DIAGRA S
WUW
VX Monitor Timing
t
RST
2901 TD
V
RTX
V
X
RST
COMPX
t
UV
1.5V
Watchdog Timing (LTC2901-1/LTC2901-2)
t
RST
t
WP
t
WD
t
WD
2901 TD2
RST
WDI
WDO
TEST CIRCUITS
Figure 1. RST, WDO, COMPX VOH Test
V1
V2
V3
V4
2901 F01
LTC2901-1
LTC2901-3
RST, WDO
OR COMPX
I
SOURCE
1μA
Figure 2. RST, WDO, COMPX VOL Test
V1
V2
V3
V4
2901 F02
LTC2901-1
LTC2901-3 ISINK
2.5mA,
100μA
RST, WDO
OR COMPX
Figure 3. Active Pull-Up RST VOH Test
V1
V2
V3
V4
2901 F03
LTC2901-2
LTC2901-4 RST
ISOURCE
200μA
Watchdog Timing (LTC2901-3/LTC2901-4)
t
RST
t
RST
t
WP
t
WD
2901 TD3
RST
WDI
5
LTC2901
2901fb
2.5V Threshold Voltage
vs Temperature
1.8V Threshold Voltage
vs Temperature
1.5V Threshold Voltage
vs Temperature
ADJ Threshold Voltage
vs Temperature
– ADJ Threshold Voltage
vs Temperature
TEMPERATURE (°C)
–60
THRESHOLD VOLTAGE, VRT25 (V)
2.3750
2.3675
2.3600
2.3525
2.3450
2.3375
2.3300
2.3225
2.3150
2.3075
2.3000
–20 20 40
2901 G04
–40 0 60 80 100
TEMPERATURE (°C)
–60
1.655
THRESHOLD VOLTAGE, V
RT18
(V)
1.665
1.675
1.685
1.695
–20 20 60 100
2901 G05
1.705
1.710
1.660
1.670
1.680
1.690
1.700
–40 0 40 80
TEMPERATURE (°C)
–60
THRESHOLD VOLTAGE, VRT15 (V)
1.425
1.420
1.415
1.410
1.405
1.400
1.395
1.390
1.385
1.380
–20 20 40
2901 G06
–40 0 60 80 100
TEMPERATURE (°C)
–60
THRESHOLD VOLTAGE, V
RTA
(V)
0.508
0.506
0.504
0.502
0.500
0.498
0.496
0.494
0.492
–20 20 40
2901 G07
–40 0 60 80 100
TEMPERATURE (°C)
–60
THRESHOLD VOLTAGE, V
RTAN
(V)
0.018
0.012
0.006
0
–0.006
–0.012
–0.018
–20 20 40
2901 G08
–40 0 60 80 100
TYPICAL PERFOR A CE CHARACTERISTICS
UW
5V Threshold Voltage
vs Temperature
3.3V Threshold Voltage
vs Temperature
3V Threshold Voltage
vs Temperature
TEMPERATURE (°C)
–60
THESHOLD VOLTAGE, V
RT50
(V)
4.675
4.700
4.750
4.725
0 40 100
2901 G01
4.650
4.625
4.600 –40 –20 20 60 80
TEMPERATURE (°C)
–60
THRESHOLD VOLTAGE, VRT33 (V)
3.135
3.125
3.115
3.105
3.095
3.085
3.075
3.065
3.055
3.045
3.035
–20 20 40
2901 G02
–40 0 60 80 100
TEMPERATURE (°C)
–60
THRESHOLD VOLTAGE, VRT30 (V)
2.850
2.840
2.830
2.820
2.810
2.800
2.790
2.780
2.770
2.760
–20 20 40
2901 G03
–40 0 60 80 100
TEMPERATURE (°C)
–60
VREF (V)
1.228
1.222
1.216
1.210
1.204
1.198
1.192
–20 20 40
2901 G23
–40 0 60 80 100
VREF vs Temperature
6
LTC2901
2901fb
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Typical Transient Duration
vs Comparator Overdrive (V1, V2)
RST Output Voltage
vs V1, VPG = 0V
Reset Time-Out Period
vs Temperature
IV2 vs Temperature IV3 vs Temperature
IV4 vs Temperature
TEMPERATURE (°C)
–60
0.5
I
V2
(μA)
0.6
0.8
0.9
1.0
1.5
1.2
–20 20 40
2901 G10
0.7
1.3
1.4
1.1
–40 0 60 80 100
V1 = 5V
V2 = 3.3V
V3 = 2.5V
V4 = 1.8V
RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V
RTX
)
0.1
250
TYPICAL TRANSIENT DURATION (μs)
300
350
400
450
110100
2901 G13
200
150
50
0
100
RESET OCCURS
ABOVE CURVE
T
A
= 25°C
V1 (V)
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
RST OUTPUT VOLTAGE (V)
2901 G14
5
4
3
2
1
0
V1 = V2 = V3 = V4
10k PULL-UP FROM RST TO V1
TA = 25°C
TEMPERATURE (°C)
–60 –40
WATCHDOG TIME-OUT PERIOD, t
WD
(ms)
34
38
36
60 80
2901 G15
32
30
–20 0 20 40 100
26
22
28
24
C
WT
= 1500pF
(SILVER MICA)
Watchdog Time-Out Period
vs Temperature
TEMPERATURE (°C)
–60
0.1
I
V3
(μA)
0.2
0.4
0.5
0.6
1.1
0.8
–20 20 40
2901 G11
0.3
0.9
1.0
0.7
–40 0 60 80 100
V1 = 5V
V2 = 3.3V
V3 = 2.5V
V4 = 1.8V
TEMPERATURE (°C)
–60
0
IV4 (μA)
0.1
0.3
0.4
0.5
1.0
0.7
–20 20 40
2901 G12
0.2
0.8
0.9
0.6
–40 0 60 80 100
V1 = 5V
V2 = 3.3V
V3 = 2.5V
V4 = 1.8V
RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V
RTX
)
0.1
80
TYPICAL TRANSIENT DURATION (μs)
100
120
140
160
1 10 100
2901 G22
60
40
20
0
200
180
220 T
A
= 25°C
RESET OCCURS
ABOVE CURVE
Typical Transient Duration
vs Comparator Overdrive (V3, V4)
TEMPERATURE (°C)
–60
4.9
RESET TIME-OUT PERIOD, tRST (ms)
5.9
6.4
6.9
8.9
7.9
–20 20 40
2901 G16
5.4
8.4
7.4
–40 0 60 80 100
CRT = 1500pF
(SILVER MICA)
IV1 vs Temperature
TEMPERATURE (°C)
–60
0
I
V1
(μA)
10
30
40
50
100
70
–20 20 40
2901 G09
20
80
90
60
–40 0 60 80 100
V1 = 5V
V2 = 3.3V
V3 = 2.5V
V4 = 1.8V
