LTC2908
Precision
Six Supply Monitor
FEATURES
■
■
DESCRIPTIO
■
■
■
■
■
■
Ultralow Voltage Reset: V
CC
= 0.5V Guaranteed*
Monitors Six Inputs Simultaneously:
5V, 3.3V, 2.5V, 1.8V, ADJ1, ADJ2 (LTC2908-A1)
3.3V, 2.5V, 1.8V, 1.5V, ADJ1, ADJ2 (LTC2908-B1)
Guaranteed Threshold Accuracy:
±
1.5% of
Monitored Voltage Over Temperature
Internal V
CC
Auto Select
Power Supply Glitch Immunity
200ms Reset Time Delay
Active Low Open-Drain RST Output
Low Profile (1mm) SOT-23 (ThinSOT
TM
) and Plastic
(2mm
×
3mm) DFN Packages
The LTC
®
2908 is a six supply monitor for systems with a
large number of supply voltages that require a precise and
compact solution. The common reset output remains low
until all six inputs have been in compliance for 200ms.
The LTC2908 features a tight 1.5% threshold accuracy
over the entire operating temperature range (– 40°C to
85°C) and glitch immunity to ensure reliable reset opera-
tion without false triggering. The open-drain RST output
state is guaranteed to be in the correct state as long as V1
and/or V2 is 0.5V or greater.
The LTC2908 also features two adjustable inputs with a
nominal threshold level at 0.5V. This product provides a
precise, space-conscious, micropower and general pur-
pose solution for any kind of system requiring supply
monitors.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
*Patent pending.
APPLICATIO S
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■
■
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Network Servers
Wireless Base Stations
Optical Networking Systems
Mulitvoltage Systems
Desktop and Notebook Computers
Handheld Devices
TYPICAL APPLICATIO
12V
DC/DC
DC/DC
DC/DC
DC/DC
DC/DC
3.3V
2.5V
Six Supply Monitor with 5% Tolerance
(12V, 3.3V, 2.5V, 1.8V, 1.5V, 1.2V)
RST Output Voltage vs V1
with 10k Pull-Up Resistor to V1
0.4
V3 = V4 = V
ADJ1
=
V
ADJ2
= GND
RST OUTPUT VOLTAGE (V)
1.8V
1.5V
1.2V
0.1µF 0.1µF
2.15M
100k
124k
100k
SYSTEM
V1
V2 V3 V4
V
ADJ1
LTC2908-B1
GND
V
ADJ2
RST
2908 TA01a
U
0.3
0.2
V2 = GND
0.1
V2 = V1
0
0
0.2
0.4
V1 (V)
2908 TA01b
U
U
0.6
0.8
sn2908 2908fs
1
LTC2908
ABSOLUTE
AXI U
RATI GS
(Notes 1, 2)
Storage Temperature Range
DFN Package .....................................–65°C to 125°C
TSOT-23 Package ..............................–65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
Terminal Voltages
V1, V2, V3, V4 ........................................ – 0.3V to 7V
V
ADJ1
, V
ADJ2
........................... – 0.3V to (V
CC
+ 0.3V)
RST ........................................................ – 0.3V to 7V
Operating Temperature Range
LTC2908C-A1/LTC2908C-B1 .................. 0°C to 70°C
LTC2908I-A1/LTC2908I-B1 ................ –40°C to 85°C
PACKAGE/ORDER I FOR ATIO
TOP VIEW
GND 1
RST 2
V4 3
V2 4
9
8
7
6
5
V
ADJ2
V3
V
ADJ1
V1
ORDER PART
NUMBER
LTC2908CDDB-A1
LTC2908IDDB-A1
LTC2908CDDB-B1
LTC2908IDDB-B1
DDB8 PART
MARKING
LBFD
LBFF
LBFG
LBFH
TOP VIEW
V2 1
V4 2
RST 3
GND 4
8 V1
7 V
ADJ1
6 V3
5 V
ADJ2
DDB8 PACKAGE
8-LEAD (3mm
×
2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 76°C/ W
EXPOSED PAD (PIN 9)
(PCB CONNECTION OPTIONAL)
Consult factory for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
RT50
V
RT33
V
RT25
V
RT18
V
RTADJ
PARAMETER
5V, 5% Reset Threshold
3.3V, 5% Reset Threshold
2.5V, 5% Reset Threshold
1.8V, 5% Reset Threshold
ADJ, 5% Reset Threshold
(LTC2908-A1) The
●
denotes specifications which apply over the full
operating temperature range, otherwise specifications are T
A
= 25°C. V
CC
= 5V, unless otherwise noted. (Note 2)
CONDITIONS
V1 Input Threshold
V2 Input Threshold
V3 Input Threshold
V4 Input Threshold
V
ADJ1
, V
ADJ2
Input Threshold
●
●
●
●
●
(LTC2908-B1) The
●
denotes specifications which apply over the full operating temperature range, otherwise specifications are
T
A
= 25°C. V
CC
= 3.3V, unless otherwise noted. (Note 2)
SYMBOL
V
RT33
V
RT25
V
RT18
V
RT15
V
RTADJ
PARAMETER
3.3V, 5% Reset Threshold
2.5V, 5% Reset Threshold
1.8V, 5% Reset Threshold
1.5V, 5% Reset Threshold
ADJ, 5% Reset Threshold
CONDITIONS
V1 Input Threshold
V2 Input Threshold
V3 Input Threshold
V4 Input Threshold
V
ADJ1
, V
ADJ2
Input Threshold
●
●
●
●
●
2
U
U
W
W W
U
W
ORDER PART
NUMBER
LTC2908CTS8-A1
LTC2908ITS8-A1
LTC2908CTS8-B1
LTC2908ITS8-B1
TS8 PART
MARKING
LTBFJ
LTBFK
LTBFM
LTBFN
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
T
JMAX
= 125°C,
θ
JA
= 250°C/ W
MIN
4.600
3.036
2.300
1.656
0.492
TYP
4.675
3.086
2.338
1.683
0.500
MAX
4.750
3.135
2.375
1.710
0.508
UNITS
V
V
V
V
V
MIN
3.036
2.300
1.656
1.380
0.492
TYP
3.086
2.338
1.683
1.403
0.500
MAX
3.135
2.375
1.710
1.425
0.508
UNITS
V
V
V
V
V
sn2908 2908fs
LTC2908
ELECTRICAL CHARACTERISTICS
SYMBOL
V
CC
I
V1
I
V2
I
V3
I
V4
I
VADJ
t
RST
t
UV
V
OH
V
OL
PARAMETER
Internal Operating Voltage
V1 Input Current
V2 Input Current
V3 Input Current
V4 Input Current
V
ADJ1
, V
ADJ2
Input Current
Reset Time-Out Period
V
X
Undervoltage Detect to RST or RST
Output Voltage High RST (Note 5)
Output Voltage Low RST
The
●
denotes specifications which apply over the full operating
temperature range, otherwise specifications are T
A
= 25°C. V
CC
= 5V for the LT2908-A1 and V
CC
= 3.3V for the LTC2908-B1, unless
otherwise noted. (Notes 2, 3)
CONDITIONS
RST in Correct Logic State
V1 = 5.0V (LTC2908-A1) (Note 4)
V1 = 3.3V (LTC2908-B1)
V2 = 3.3V (LTC2908-A1) (Note 4)
V2 = 2.5V (LTC2908-B1)
V3 = 2.5V (LTC2908-A1)
V3 = 1.8V (LTC2908-B1)
V4 = 1.8V (LTC2908-A1)
V4 = 1.5V (LTC2908-B1)
V
ADJ1
= V
ADJ2
= 0.55V
V
X
Less Than Reset Threshold V
RTX
by
More Than 1%
I
RST
= –1µA, V
CC
= 5V (LTC2908-A1)
I
RST
= –1µA, V
CC
= 3.3V (LTC2908-B1)
V
CC
= 0.5V, I
RST
= 5µA
V
CC
= 1.0V, I
RST
= 100µA
V
CC
= 3.0V, I
RST
= 2500µA
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
MIN
0.5
TYP
26
24
10
8
2
2
2
2
MAX
6
50
50
20
20
5
5
5
5
±15
260
UNITS
V
µA
µA
µA
µA
µA
µA
µA
µA
nA
ms
µs
V
V
160
200
250
V
CC
– 1.5
V
CC
– 1.0
0.01
0.01
0.10
0.15
0.15
0.30
V
V
V
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The greater of V1, V2 is the internal supply voltage (V
CC
).
Note 3:
All currents into pins are positive; all voltages are referenced to
GND unless otherwise noted.
Note 4:
Under typical operating conditions, most of the quiescent current
is drawn from the V1 input. When V2 exceeds V1, V2 supplies most of the
quiescent current.
Note 5:
The output pin RST has an internal pull-up to V
CC
of typically 6µA.
However, an external pull-up resistor may be used when a faster rise time
is required or for V
OH
voltages greater than V
CC
.
TYPICAL PERFOR A CE CHARACTERISTICS
Specifications are at T
A
= 25°C unless otherwise noted.
5V Threshold Voltage
vs Temperature
4.750
THRESHOLD VOLTAGE, V
RT50
(V)
THRESHOLD VOLTAGE, V
RT33
(V)
4.725
4.700
4.675
4.650
4.625
4.600
–50
3.115
THRESHOLD VOLTAGE, V
RT25
(V)
–25
50
25
0
TEMPERATURE (°C)
U W
75
2908 G01
3.3V Threshold Voltage
vs Temperature
3.135
2.375
2.5V Threshold Voltage
vs Temperature
2.360
3.095
2.345
3.075
2.330
3.055
2.315
100
3.035
–50
–25
50
25
0
TEMPERATURE (°C)
75
100
2908 G02
2.300
–50
–25
50
25
0
TEMPERATURE (°C)
75
100
2908 G03
sn2908 2908fs
3
LTC2908
TYPICAL PERFOR A CE CHARACTERISTICS
Specifications are at T
A
= 25°C unless otherwise noted.
1.8V Threshold Voltage
vs Temperature
1.710
THRESHOLD VOLTAGE, V
RT18
(V)
THRESHOLD VOLTAGE, V
RT15
(V)
1.700
1.415
1.410
1.405
1.400
1.395
1.390
1.385
THRESHOLD VOLTAGE, V
RTADJ
(V)
1.690
1.680
1.670
1.660
–50
–25
50
25
0
TEMPERATURE (°C)
I
V1
vs Temperature
33
V1 = 5.0V (A1)/V1 = 3.3V (B1)
31 V2 = 3.3V (A1)/V2 = 2.5V (B1)
V3 = 2.5V (A1)/V3 = 1.8V (B1)
29 V4 = 1.8V (A1)/V4 = 1.5V (B1)
V
ADJ1
= V
ADJ2
= 0.55V
27
I
V1
(µA)
A1
25
23
21
19
17
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
2908 G07
B1
I
V2
(µA)
9
8
7
6
5
4
–50
–25
A1
B1
I
V3
(µA)
I
V4
vs Temperature
TYPICAL TRANSIENT DURATION (µs)
600
500
400
300
200
100
0
0.1
1
10
100
COMPARATOR OVERDRIVE VOLTAGE (% OF V
RTX
)
2908 G11
RESET TIME-OUT PERIOD, t
RST
(ms)
V1 = 5.0V (A1)/V1 = 3.3V (B1)
2.1 V2 = 3.3V (A1)/V2 = 2.5V (B1)
V3 = 2.5V (A1)/V3 = 1.8V (B1)
2.0 V4 = 1.8V (A1)/V4 = 1.5V (B1)
V
ADJ1
= V
ADJ2
= 0.55V
1.9
I
V4
(µA)
2.2
1.8
1.7
1.6
1.5
1.4
–50
–25
50
25
TEMPERATURE (°C)
0
75
100
2908 G10
4
U W
75
2908 G04
1.5V Threshold Voltage
vs Temperature
1.425
1.420
0.5080
0.5060
0.5040
0.5020
0.5000
0.4980
0.4960
0.4940
ADJ Threshold Voltage
vs Temperature
1.380
100
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
0.4920
–50
–25
50
25
TEMPERATURE (°C)
0
75
100
2908 G06
2908 G05
I
V2
vs Temperature
V1 = 5.0V (A1)/V1 = 3.3V (B1)
13 V2 = 3.3V (A1)/V2 = 2.5V (B1)
V3 = 2.5V (A1)/V3 = 1.8V (B1)
12 V4 = 1.8V (A1)/V4 = 1.5V (B1)
11 V
ADJ1
= V
ADJ2
= 0.55V
10
14
I
V3
vs Temperature
V1 = 5.0V (A1)/V1 = 3.3V (B1)
2.1 V2 = 3.3V (A1)/V2 = 2.5V (B1)
V3 = 2.5V (A1)/V3 = 1.8V (B1)
2.0 V4 = 1.8V (A1)/V4 = 1.5V (B1)
V
ADJ1
= V
ADJ2
= 0.55V
1.9
1.8
1.7
1.6
1.5
2.2
50
25
TEMPERATURE (°C)
0
75
100
2908 G08
1.4
–50
–25
0
50
25
TEMPERATURE (°C)
75
100
2908 G09
Typical Transient Duration
vs Comparator Overdrive
700
T
A
= 25°C
250
240
230
220
210
200
190
180
170
160
Reset Time-Out Period (t
RST
)
vs Temperature
RESET OCCURS
ABOVE CURVE
150
–50
–25
0
50
25
TEMPERATURE (°C)
75
100
2908 G12
sn2908 2908fs
LTC2908
TYPICAL PERFOR A CE CHARACTERISTICS
Specifications are at T
A
= 25°C unless otherwise noted.
RST Output Voltage vs V1 with
10k Pull-Up Resistor to V1
5.0
V1 = V2
V3 = 2.5V (A1)/V3 = 1.8V (B1)
V4 = 1.8V (A1)/V4 = 1.5V (B1)
V
ADJ1
= V
ADJ2
= 0.55V
0.4
RST PULL-DOWN CURRENT, I
RST
(mA)
RST OUTPUT VOLTAGE (V)
RST OUTPUT VOLTAGE (V)
4.0
3.0
2.0
1.0
V
RT33
LTC2908-B1
0
0
1
2
V1 (V)
2908 G13
V
RT50
LTC2908-A1
4
5
0
0
0.2
3
RST Pull-Down Current (I
RST
) vs
Supply Voltage (V
CC
) with Dual
Channel Supply
10
RST PULL-DOWN CURRENT, I
RST
(mA)
RST PULL-DOWN CURRENT, I
RST
(mA)
V
CC
= V1 = V2
V3 = V4 = V
ADJ1
= V
ADJ2
= GND
RST AT 150mV
10
1
1
RST OUTPUT VOLTAGE LOW, V
OL
(V)
0.1
RST AT 50mV
0.01
0.001
0
0.2
0.4
0.6
0.8
SUPPLY VOLTAGE, V
CC
(V)
1
2908 G16
RST Output Voltage Low (V
OL
)
vs RST Pull-Down Current (I
RST
)
LTC2908-B1
0.8
RST OUTPUT VOLTAGE LOW, V
OL
(V)
RST PULL-UP CURRENT, I
RST
(µA)
V1 = 3.3V
0.7 V2 = 2.5V
V3 = 1.8V
0.6 V4 = 1.5V
V
ADJ1
= V
ADJ2
= 0.4V
0.5
85°C
0.4
25°C
0.3
0.2
0.1
0
0
20
15
RST PULL-DOWN CURRENT, I
RST
(mA)
5
10
25
–40°C
U W
RST Output Voltage vs V1 with
10k Pull-Up Resistor to V1
V3 = V4 = V
ADJ1
=
V
ADJ2
= GND
6
5
4
3
2
1
0
RST Pull-Down Current (I
RST
)
vs Supply Voltage (V
CC
)
V
CC
= V1 = V2
V3 = V4 = V
ADJ1
= V
ADJ2
= GND
RST AT
150mV
0.3
0.2
V2 = GND
0.1
V2 = V1
RST AT
50mV
V
RT50
V
RT33
LTC2908-B1 LTC2908-A1
0
1
2
3
4
SUPPLY VOLTAGE, V
CC
(V)
5
2908 G15
0.4
V1 (V)
0.6
0.8
2908 G14
RST Pull-Down Current (I
RST
) vs
Supply Voltage (V
CC
) with Single
Channel Supply
V
CC
= V1
V2 = V3 = V4 = V
ADJ1
= V
ADJ2
= GND
RST Output Voltage Low (V
OL
)
vs RST Pull-Down Current (I
RST
)
LTC2908-A1
0.8
V1 = 5.0V
0.7 V2 = 3.3V
V3 = 2.5V
0.6 V4 = 1.8V
V
ADJ1
= V
ADJ2
= 0.4V
0.5
85°C
0.4
25°C
0.3
0.2
0.1
0
0
20
25
30
35
15
RST PULL-DOWN CURRENT, I
RST
(mA)
2908 G18
RST AT 150mV
0.1
–40°C
RST AT 50mV
0.01
0.001
0
0.2
0.4
0.6
0.8
SUPPLY VOLTAGE, V
CC
(V)
1
2908 G17
5
10
RST Pull-Up Current (I
RST
)
vs Supply Voltage (V
CC
)
–30
–25
–20
–15
–10
–5
V
RT33
LTC2908-B1
0
2
2.5
V
RT50
LTC2908-A1
5
2908 G20
V
CC
= V1 = V2
V3 = 2.5V (A1)/V3 = 1.8V (B1)
V4 = 1.8V (A1)/V4 = 1.5V (B1)
V
ADJ1
= V
ADJ2
= 0.55V
RST HELD AT 0V
4.5
3
3.5
4
SUPPLY VOLTAGE, V
CC
(V)
2908 G19
sn2908 2908fs
5
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