LTC2904/LTC2905
Precision Dual Supply Monitors
with Pin-Selectable Thresholds
FEATURES
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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
TM
) 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 and LTM 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
29045fc
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
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
= 125°C,
θ
JA
= 76°C/W
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
* RST FOR LTC2904
TMR FOR LTC2905
T
JMAX
= 125°C,
θ
JA
= 195°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC2904CDDB#TRMPBF
LTC2904IDDB#TRMPBF
LTC2905CDDB#TRMPBF
LTC2905IDDB#TRMPBF
LTC2904CTS8#TRMPBF
LTC2904ITS8#TRMPBF
LTC2905CTS8#TRMPBF
LTC2905ITS8#TRMPBF
LEAD BASED FINISH
LTC2904CDDB#TRM
LTC2904IDDB#TRM
LTC2905CDDB#TRM
LTC2905IDDB#TRM
LTC2904CTS8#TRM
LTC2904ITS8#TRM
LTC2905CTS8#TRM
TAPE AND REEL
LTC2904CDDB#TRPBF
LTC2904IDDB#TRPBF
LTC2905CDDB#TRPBF
LTC2905IDDB#TRPBF
LTC2904CTS8#TRPBF
LTC2904ITS8#TRPBF
LTC2905CTS8#TRPBF
LTC2905ITS8#TRPBF
TAPE AND REEL
LTC2904CDDB#TR
LTC2904IDDB#TR
LTC2905CDDB#TR
LTC2905IDDB#TR
LTC2904CTS8#TR
LTC2904ITS8#TR
LTC2905CTS8#TR
PART MARKING
LBCZ
LBDB
LAJF
LBCY
LTBCJ
LTBCK
LTAJD
LTAJE
PART MARKING
LBCZ
LBDB
LAJF
LBCY
LTBCJ
LTBCK
LTAJD
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 Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
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 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 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
LTC2905ITS8#TRM
LTC2905ITS8#TR
LTAJE
8-Lead Plastic TSOT-23
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/
29045fc
2
LTC2904/LTC2905
ELECTRICAL CHARACTERISTICS
SYMBOL
V
RT50
V
RT33
V
RT25
V
RT18
V
RT15
V
RT12
V
RT10
V
CCMIN
I
V1
I
V2
I
TMR(UP)
I
TMR(DOWN)
t
RST
t
RST
t
UV
V
OL
V
OH
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
Reset Time-Out Period
Reset Time-Out Period
(LTC2905)
(LTC2904)
(LTC2905)
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
V
TMR
= 0V
V
TMR
= 1.4V
TMR Pull-Down Current (LTC2905)
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
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
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
260
260
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
ms
ms
μs
V1, V2 Input Threshold
V1, V2 Input Threshold
V2 Input Threshold
V2 Input Threshold
V2 Input Threshold
V2 Input Threshold
RST
in Correct Logic State
Includes Input Current to Three-State Pins
–1.5
1.5
140
140
–2.1
2.1
200
200
150
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
V
IH
V
Z
I
VPG
Low Level Input Voltage
High Level Input Voltage
Pin Voltage when Left in Open State
V
V
V
l
l
0.4
1.4
0.7
0.9
1.1
±25
V
V
V
V
V
μA
I = –10μA
I = 0μA
I = 10μA
l
l
l
Programming Input Current (Note 6)
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.
29045fc
3
LTC2904/LTC2905
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
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
29045fc
4
LTC2904/LTC2905
TYPICAL PERFORMANCE CHARACTERISTICS
Specifications are at T
A
= 25°C unless otherwise noted.
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
10n
C
TMR
(FARAD)
1n
100n
1
29045 G12
Reset Time-Out 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)
RST Output Voltage vs V1
5
RST PULL-DOWN CURRENT, I
RST
(mA)
4
RST OUTPUT VOLTAGE (V)
3
2
1
0
–1
V2 = S1 = S2 = TOL = V1
10pF CAPACITOR AT RST
5
4
RST
Pull-Down Current (I
RST
)
vs Supply Voltage (V
CC
)
RST PULL-DOWN CURRENT, I
RST
(mA)
V2 = S1 = S2 = TOL = V1
NO PULL-UP R
5
4
RST Pull-Down Current (I
RST
)
vs Supply Voltage (V
CC
)
S1 = V2 = V1
TOL = S2 = GND
NO PULL-UP R
RST AT 150mV
3
2
1
0
0
1
2
3
4
SUPPLY VOLTAGE, V
CC
(V)
5
29045 G17
RST AT 150mV
3
2
1
0
0
1
2
3
4
SUPPLY VOLTAGE, V
CC
(V)
5
29045 G18
RST AT 50mV
RST AT 50mV
0
1
2
V1 (V)
3
4
5
29045 G16
29045fc
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