LTC2904/LTC2905
Precision Dual Supply Monitors
with Pin-Selectable Thresholds
FEATURES
s
s
s
s
DESCRIPTIO
s
s
s
s
s
s
s
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 x 2mm) DFN Packages
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 external
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.
APPLICATIO S
s
s
s
s
Desktop and Notebook Computers
Handheld Devices
Network Servers
Core, I/O Monitor
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
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
3.3
3.3
2.5
2.5
2.5
2.5
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
29045 TA01
U
29045f
U
U
1
LTC2904/LTC2905
ABSOLUTE
AXI U RATI GS
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
PACKAGE/ORDER I FOR ATIO
TOP VIEW
GND 1
RST 2
RST/TMR* 3
V2 4
9
8
7
6
5
TOL
S1
S2
V1
ORDER PART
NUMBER
LTC2904CDDB8
LTC2904IDDB8
LTC2905CDDB8
LTC2905IDDB8
DDB8 PART MARKING
LBCZ
LBDB
LTAJF
LBCY
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
= 250°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The
q
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, 4)
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
CONDITIONS
V1 Input Threshold
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
ELECTRICAL CHARACTERISTICS
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
2
U
U
W
W W
U
W
(Note 1, 2)
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
Lead Temperature (Soldering, 10 sec).................. 300°C
TOP VIEW
V2 1
RST/TMR* 2
RST 3
GND 4
8 V1
7 S2
6 S1
5 TOL
ORDER PART
NUMBER
LTC2904CTS8
LTC2904ITS8
LTC2905CTS8
LTC2905ITS8
TS8 PART MARKING
LTBCJ
LTBCK
LTAJD
LTAJE
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
* RST FOR LTC2904
TMR FOR LTC2905
T
JMAX
= 125°C,
θ
JA
= 250°C/W
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
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
UNITS
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
29045f
LTC2904/LTC2905
The
q
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)
SYMBOL
V
CCMIN
I
V1
I
V2
I
TMR(UP)
I
TMR(DOWN)
t
RST
t
RST
t
UV
V
OL
V
OH
PARAMETER
V1 Input Current
V2 Input Current
TMR Pull-Up Current
TMR Pull-Down Current
Reset Time-Out Period
Reset Time-Out Period
Vx Undervoltage Detect to
RST or RST
Output Voltage Low RST, RST
Output Voltage High RST, RST
(Notes 2, 5)
Low Level Input Voltage
High Level Input Voltage
Pin Voltage when Left in Open State
I = –10µA
I = 0µA
I = 10µA
(LTC2905)
(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
q
q
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
q
q
q
MIN
TYP
65
0.4
MAX
1
130
1.0
–2.7
2.7
260
260
UNITS
V
µA
µA
µA
µA
ms
ms
µs
Minimum Internal Operating Voltage (Note 2) RST in Correct Logic State
Includes Input Current to Three-State Pins
V
TMR
= 0V
V
TMR
= 1.4V
q
q
q
q
–1.5
1.5
140
140
–2.1
2.1
200
200
150
0.15
0.05
0.4
0.3
V
V
V
V
CC
–1
Three-State Inputs S1, S2, TOL
V
IL
V
IH
V
Z
q
q
q
q
q
0.4
1.4
0.7
0.9
1.1
±25
V
V
V
V
V
µA
I
VPG
Programming Input Current (Note 6)
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:
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.
29045f
3
LTC2904/LTC2905
TYPICAL PERFOR A CE CHARACTERISTICS
Specifications are at T
A
= 25°C unless otherwise noted.
5V Threshold Voltage vs
Temperature
4.75
3.120
5%
THRESHOLD VOLTAGE, V
RT50
(V)
THRESHOLD VOLTAGE, V
RT33
(V)
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
3.070
THRESHOLD VOLTAGE, V
RT25
(V)
4.70
5%
7.5%
10%
1.8V Threshold Voltage vs
Temperature
1.705
1.425
5%
THRESHOLD VOLTAGE, V
RT18
(V)
THRESHOLD VOLTAGE, V
RT15
(V)
1.405
1.385
7.5%
1.365
1.345
10%
1.325
1.305
–50
THRESHOLD VOLTAGE, V
RT12
(V)
1.685
1.665
1.645
1.625
1.605
1.585
1.565
–50
7.5%
10%
–25
25
50
0
TEMPERATURE (°C)
1V Threshold Voltage vs
Temperature
0.950
21.5
5%
21.0
0.930
0.920
THRESHOLD VOLTAGE, V
RT10
(V)
0.940
I
V1
(µA)
0.910
0.900
0.890
0.880
0.870
–50
–25
7.5%
I
V2
(µA)
10%
25
50
0
TEMPERATURE (°C)
4
U W
75
29045 G04
3.3V Threshold Voltage vs
Temperature
2.375
2.5V Threshold Voltage vs
Temperature
5%
2.325
7.5%
2.275
3.020
7.5%
2.970
10%
2.920
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
1.5V Threshold Voltage vs
Temperature
1.135
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%
10%
100
1.045
–50
–25
25
50
0
TEMPERATURE (°C)
75
100
29045 G06
I
V1
vs Temperature
V1 = 5V
V2 = 3.3V
S1 = S2 = TOL = 1.4V
1.8
1.7
1.6
20.5
1.5
1.4
19.5
1.3
I
V2
vs Temperature
V1 = 5V
V2 = 3.3V
S1 = S2 = TOL = 1.4V
20.0
75
100
29045 G07
19.0
–50
–25
25
50
0
TEMPERATURE (°C)
75
100
29045 G08
1.2
–50
–25
25
50
0
TEMPERATURE (°C)
75
100
29045 G09
29045f
LTC2904/LTC2905
TYPICAL PERFOR A CE CHARACTERISTICS
Specifications are at T
A
= 25°C unless otherwise noted.
Typical Transient Duration vs
Comparator Overdrive (V1, V2)
700
10000
I
V2
vs Temperature
20.0
19.5
19.0
TYPICAL TRANSIENT DURATION (µs)
RESET TIME OUT PERIOD, t
RST
(ms)
V1 = 2.5V
V2 = 3.3V
S1 = S2 = TOL = 1.4V
I
V2
(µA)
18.5
18.0
17.5
17.0
–50
–25
25
50
0
TEMPERATURE (°C)
Reset Time-Out Period (t
RST
)
vs Temperature
235
5
RESET TIME-OUT PERIOD, t
RST
(ms)
CRT = 22nF
230 (FILM)
225
220
215
210
205
200
195
–50
–25
0
25
50
75
100
29045 G13
RST OUTPUT VOLTAGE (V)
RST OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
RST Output Voltage vs V1
5
RST PULL-DOWN CURRENT, I
RST
(mA)
4
4
RST AT 150mV
3
2
1
0
RST PULL-DOWN CURRENT, I
RST
(mA)
V2 = S1 = S2 = TOL = V1
10pF CAPACITOR AT RST
RST OUTPUT VOLTAGE (V)
3
2
1
0
–1
0
1
2
V1 (V)
3
U W
75
100
29045 G10
Reset Time Out Period (t
RST
)
vs Capacitance (C
TMR
)
600
500
400
300
200
100
0
1
10
100
0.1
COMPARATOR OVERDRIVE VOLTAGE (% OF V
RTX
)
29045 G11
1000
RESET OCCURS
ABOVE CURVE
100
10
1
0.1
10p
100p
1n
10n
C
TMR
(FARAD)
100n
1µ
29045 G12
RST Output Voltage vs V1
5
V2 = S1 = S2 = TOL = V1
10k PULL-UP RESISTOR
4
3
2
1
0
–1
4
3
2
1
0
–1
RST Output Voltage vs V1
V2 = S1 = S2 = TOL = V1
10k PULL-UP RESISTOR
0
1
2
V1 (V)
3
4
5
29045 G14
0
1
2
V1 (V)
3
4
5
29045 G15
RST Pull-Down Current (I
RST
)
vs Supply Voltage (V
CC
)
5
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
RST AT 50mV
RST AT 50mV
4
5
29045 G16
0
1
2
3
4
SUPPLY VOLTAGE, V
CC
(V)
5
29045 G17
0
1
2
3
4
SUPPLY VOLTAGE, V
CC
(V)
5
29045 G18
29045f
5
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
