FEATURES
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LTC2904/LTC2905
Precision Dual Supply
Monitors with Pin-Selectable
Thresholds
DESCRIPTION
The LTC
®
2904/LTC2905 are dual supply monitors in-
tended for systems with two supply voltages. The dual
supply monitors have a common reset output with delay
(200ms for the LTC2904 and adjustable using an exter-
nal capacitor for the LTC2905). This product provides a
precise, space-conscious and micropower solution for
supply monitoring.
The LTC2904/LTC2905 feature a tight 1.5% threshold
accuracy over the whole operating temperature range, and
glitch immunity to ensure reliable reset operation without
false triggering. The open drain
RST
output is guaranteed
to be in the correct state for inputs down to 1V.
The LTC2904/LTC2905 also feature three programming
input pins, which program the threshold and tolerance level
without requiring any external components. These three
programming pins provide a total of 27 different voltage
level and tolerance combinations, eliminating the need to
have different parts for development and implementation
of different systems with different voltage levels requiring
monitoring function.
Monitors Two Inputs Simultaneously
Nine Threshold Combinations
Three Supply Tolerances (5%, 7.5%, 10%)
Guaranteed Threshold Accuracy:
±1.5%
of
Monitored Voltage Over Temperature
Internal V
CC
Auto Select
Power Supply Glitch Immunity
200ms Reset Time Delay (LTC2904 Only)
Adjustable Reset Time Delay (LTC2905 Only)
Open Drain
RST
Output
Guaranteed
RST
for V1 ≥ 1V or V2 ≥ 1V
Low Profile (1mm) SOT-23 (ThinSOT™) and
Plastic (3mm
×
2mm) DFN Packages
APPLICATIONS
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Desktop and Notebook Computers
Handheld Devices
Network Servers
Core, I/O Monitor
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
5V, 3.3V Dual Supply Monitor with 5% Tolerance
DC/DC
CONVERTER
5V
3.3V
SYSTEM
LOGIC
Table 1. Voltage Threshold Programming
V1
5.0
3.3
3.3
V2
3.3
2.5
1.8
1.5
1.2
1.8
1.5
1.2
1.0
S1
V1
Open
V1
Open
Open
GND
GND
GND
V1
S2
V1
GND
Open
V1
Open
GND
Open
V1
GND
V1
0.1μF
S1
S2
TOL
LTC2905
V2
0.1μF
TMR
22nF
GND
RST
3.3
3.3
2.5
2.5
29045 TA01
2.5
2.5
29045fd
1
LTC2904/LTC2905
ABSOLUTE MAXIMUM RATINGS
(Note 1, 2)
Terminal Voltages
V1, V2 ...................................................... –0.3V to 7V
S1, S2, TOL ................................–0.3V to (V
CC
+0.3V)
RST
.......................................................... –0.3V to 7V
RST (LTC2904) ........................................ –0.3V to 7V
TMR (LTC2905) ....................................... –0.3V to 7V
Operating Temperature Range
LTC2904C/LTC2905C .............................. 0°C to 70°C
LTC2904I/LTC2905I.............................–40°C to 85°C
LTC2905H .......................................... –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
TSOT Lead Temperature (Soldering, 10 sec) ......... 300°C
PIN CONFIGURATION
TOP VIEW
GND 1
RST
2
RST/TMR* 3
V2 4
9
8
7
6
5
TOL
S1
S2
V1
V2 1
RST/TMR* 2
RST
3
GND 4
TOP VIEW
8 V1
7 S2
6 S1
5 TOL
DDB8 PACKAGE
8-LEAD (3mm 2mm) PLASTIC DFN
EXPOSED PAD IS GND (PIN 9),
MUST BE SOLDERED TO PCB
* RST FOR LTC2904
TMR FOR LTC2905
T
JMAX
= 150°C,
θ
JA
= 76°C/W
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
* RST FOR LTC2904
TMR FOR LTC2905
T
JMAX
= 150°C,
θ
JA
= 195°C/W
ORDER INFORMATION
Lead Free Finish
TAPE AND REEL (MINI)
LTC2904CDDB#TRMPBF
LTC2904IDDB#TRMPBF
LTC2905CDDB#TRMPBF
LTC2905HDDB#TRMPBF
LTC2905IDDB#TRMPBF
LTC2904CTS8#TRMPBF
LTC2904ITS8#TRMPBF
LTC2905CTS8#TRMPBF
LTC2905HTS8#TRMPBF
TAPE AND REEL
LTC2904CDDB#TRPBF
LTC2904IDDB#TRPBF
LTC2905CDDB#TRPBF
LTC2905HDDB#TRPBF
LTC2905IDDB#TRPBF
LTC2904CTS8#TRPBF
LTC2904ITS8#TRPBF
LTC2905CTS8#TRPBF
LTC2905HTS8#TRPBF
PART MARKING*
LBCZ
LBDB
LAJF
LBCY
LBCY
LTBCJ
LTBCK
LTAJD
LTAJE
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
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 125°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 125°C
–40°C to 85°C
LTC2905ITS8#TRMPBF
LTC2905ITS8#TRPBF
LTAJE
8-Lead Plastic TSOT-23
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on 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/
29045fd
2
LTC2904/LTC2905
ELECTRICAL CHARACTERISTICS
SYMBOL
V
RT50
PARAMETER
5V, 5% Reset Threshold
5V, 7.5% Reset Threshold
5V, 10% Reset Threshold
3.3V, 5% Reset Threshold
3.3V, 7.5% Reset Threshold
3.3V, 10% Reset Threshold
2.5V, 5% Reset Threshold
2.5V, 7.5% Reset Threshold
2.5V, 10% Reset Threshold
1.8V, 5% Reset Threshold
1.8V, 7.5% Reset Threshold
1.8V, 10% Reset Threshold
1.5V, 5% Reset Threshold
1.5V, 7.5% Reset Threshold
1.5V, 10% Reset Threshold
1.2V, 5% Reset Threshold
1.2V, 7.5% Reset Threshold
1.2V, 10% Reset Threshold
1V, 5% Reset Threshold
1V, 7.5% Reset Threshold
1V, 10% Reset Threshold
Minimum Internal Operating Voltage (Note 2)
V1 Input Current
V2 Input Current
TMR Pull-Up Current
TMR Pull-Down Current
Reset Timeout Period
Reset Timeout Period
LTC2905
LTC2905
LTC2905H
LTC2904
LTC2905
LTC2905H
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V1 = 2.5V, V2 = 1V, S1 = TOL = V1, S2 = 0V, unless otherwise noted.
(Notes 2, 3)
CONDITIONS
V1 Input Threshold
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
V
RT33
V1, V2 Input Threshold
V
RT25
V1, V2 Input Threshold
V
RT18
V2 Input Threshold
V
RT15
V2 Input Threshold
V
RT12
V2 Input Threshold
V
RT10
V2 Input Threshold
RST
in Correct Logic State
Includes Input Current to Three-State Pins
V
TMR
= 0V
V
TMR
= 1.4V
MIN
4.600
4.475
4.350
3.036
2.954
2.871
2.300
2.238
2.175
1.656
1.611
1.566
1.380
1.343
1.305
1.104
1.074
1.044
0.920
0.895
0.870
TYP
4.675
4.550
4.425
3.086
3.003
2.921
2.338
2.275
2.213
1.683
1.638
1.593
1.403
1.365
1.328
1.122
1.092
1.062
0.935
0.910
0.885
65
0.4
V
CCMIN
I
V1
I
V2
I
TMR(UP)
I
TMR(DOWN)
t
RST
t
RST
t
UV
V
OL
V
OH
MAX
4.750
4.625
4.500
3.135
3.053
2.970
2.375
2.313
2.250
1.710
1.665
1.620
1.425
1.388
1.350
1.140
1.110
1.080
0.950
0.925
0.900
1
130
1.0
–2.7
2.7
2.7
260
260
295
UNITS
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
μA
μA
μA
μA
μA
ms
ms
ms
μs
V
V
V
–1.5
1.5
1.4
140
140
140
–2.1
2.1
2.0
200
200
150
C
TMR
= 22nF
Vx Less than Reset Threshold V
RTX
by More than 1%
I = 2.5mA
I = 100μA; V1 = 1V (RST Only)
I = –1μA
Vx Undervoltage Detect to
RST or
RST
Output Voltage Low RST,
RST
l
l
l
0.15
0.05
V
CC
–1
0.4
0.3
Output Voltage High RST,
RST
(Notes 2, 5)
Three-State Inputs S1, S2, TOL
V
IL
Low Level Input Voltage
V
IH
High Level Input Voltage
V
Z
Pin Voltage When Left in Open State
l
l
0.4
1.4
0.7
0.9
1.1
0.65
0.9
1.15
±25
2905H
I = –10μA
I = 0μA
I = 10μA
I = –10μA
I = 0μA
I = 10μA
l
l
l
l
l
I
VPG
Programming Input Current (Note 6)
V
V
V
V
V
V
V
V
μA
29045fd
3
LTC2904/LTC2905
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:
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:
For reset thresholds test conditions refer to the voltage threshold
programming table in the Applications Information section.
Note 5:
The output pins
RST
and RST have an internal pull-up to V
CC
of
typically –6μA. However, an external pull-up resistor may be used when
faster rise time is required or for V
OH
voltages greater than V
CC
.
Note 6:
The input current to the three-state input pins are the pull-up
and the pull-down current when the pins are either set to V1 or GND
respectively. In the open state, the maximum leakage current to V1 or GND
permissible is 10μA.
TYPICAL PERFORMANCE CHARACTERISTICS
Specifications are at T
A
= 25°C unless otherwise noted.
5V Threshold Voltage
vs Temperature
4.75
THRESHOLD VOLTAGE, V
RT50
(V)
THRESHOLD VOLTAGE, V
RT33
(V)
4.70
4.65
4.60
4.55
4.50
4.45
4.40
4.35
–50
–25
25
50
0
TEMPERATURE ( C)
75
100
29045 G01
3.3V Threshold Voltage
vs Temperature
3.120
5%
3.070
THRESHOLD VOLTAGE, V
RT25
(V)
2.375
2.5V Threshold Voltage
vs Temperature
5%
2.325
7.5%
2.275
5%
3.020
7.5%
7.5%
2.970
10%
2.920
10%
2.225
10%
2.870
–50
–25
25
50
0
TEMPERATURE ( C)
75
100
29045 G02
2.175
–50
–25
25
50
0
TEMPERATURE ( C)
75
100
29045 G03
1.8V Threshold Voltage
vs Temperature
1.705
THRESHOLD VOLTAGE, V
RT18
(V)
THRESHOLD VOLTAGE, V
RT15
(V)
1.685
1.665
1.645
1.625
1.605
1.585
1.565
–50
10%
7.5%
5%
1.405
1.385
1.425
1.5V Threshold Voltage
vs Temperature
1.135
THRESHOLD VOLTAGE, V
RT12
(V)
5%
1.125
1.115
1.105
1.095
1.085
1.075
1.065
1.055
–25
25
50
0
TEMPERATURE ( C)
75
100
29045 G05
1.2V Threshold Voltage
vs Temperature
5%
7.5%
1.365
1.345
10%
1.325
1.305
–50
7.5%
10%
–25
25
50
0
TEMPERATURE ( C)
75
100
29045 G04
1.045
–50
–25
25
50
0
TEMPERATURE ( C)
75
100
29045 G06
29045fd
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LTC2904/LTC2905
TYPICAL PERFORMANCE CHARACTERISTICS
Specifications are at T
A
= 25°C unless otherwise noted.
1V Threshold Voltage
vs Temperature
0.950
THRESHOLD VOLTAGE, V
RT10
(V)
0.940
0.930
0.920
I
V1
( A)
0.910
0.900
0.890
0.880
0.870
–50
–25
25
50
0
TEMPERATURE ( C)
75
100
29045 G07
I
V1
vs Temperature
21.5
V1 = 5V
V2 = 3.3V
S1 = S2 = TOL = 1.4V
1.8
1.7
1.6
I
V2
vs Temperature
V1 = 5V
V2 = 3.3V
S1 = S2 = TOL = 1.4V
5%
21.0
7.5%
I
V2
( A)
25
50
0
TEMPERATURE ( C)
20.5
1.5
1.4
20.0
10%
19.5
1.3
1.2
–50
19.0
–50
–25
75
100
29045 G08
–25
25
50
0
TEMPERATURE ( C)
75
100
29045 G09
I
V2
vs Temperature
20.0
19.5
19.0
I
V2
( A)
18.5
18.0
17.5
17.0
–50
700
TYPICAL TRANSIENT DURATION ( s)
V1 = 2.5V
V2 = 3.3V
S1 = S2 = TOL = 1.4V
600
500
400
300
200
100
0
–25
25
50
0
TEMPERATURE ( C)
75
100
29045 G10
Typical Transient Duration
vs Comparator Overdrive (V1, V2)
10000
RESET TIME OUT PERIOD, t
RST
(ms)
Reset Time Out Period (t
RST
)
vs Capacitance (C
TMR
)
1000
RESET OCCURS
ABOVE CURVE
100
10
1
1
10
100
0.1
COMPARATOR OVERDRIVE VOLTAGE (% OF V
RTX
)
29045 G11
0.1
10p
100p
1n
10n
C
TMR
(FARAD)
100n
1
29045 G12
Reset Timeout Period (t
RST
)
vs Temperature
235
RESET TIME-OUT PERIOD, t
RST
(ms)
5
CRT = 22nF
230 (FILM)
225
220
215
210
205
200
195
–50
–25
0
25
50
75
100
29045 G13
RST
Output Voltage vs V1
5
V2 = S1 = S2 = TOL = V1
10k PULL-UP RESISTOR
4
RST OUTPUT VOLTAGE (V)
RST OUTPUT VOLTAGE (V)
3
2
1
0
–1
RST Output Voltage vs V1
V2 = S1 = S2 = TOL = V1
10k PULL-UP RESISTOR
4
3
2
1
0
–1
0
1
2
V1 (V)
3
4
5
29045 G14
0
1
2
V1 (V)
3
4
5
29045 G15
TEMPERATURE ( C)
29045fd
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