LTC2900
Programmable Quad Supply
Monitor with Adjustable Reset Timer
FEATURES
s
s
DESCRIPTIO
s
s
s
s
s
s
s
s
s
Simultaneously Monitors Four Supplies
16 User Selectable Combinations of 5V, 3.3V, 3V,
2.5V, 1.8V, 1.5V and/or
±Adjustable
Voltage
Thresholds
Guaranteed Threshold Accuracy:
±1.5%
of
Monitored Voltage Over Temperature
Low Supply Current: 43µA Typ
Adjustable Reset Time
Small MSOP and 3mm
×
3mm DFN Packages
Manual Reset Pin
Open-Drain RST Output (LTC2900-1)
Push-Pull RST Output (LTC2900-2)
Power Supply Glitch Immunity
Guaranteed RST for V
CC
≥
1V
The LTC
®
2900 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.
The reset delay time is adjustable using an external
capacitor and the manual reset input may be used with a
momentary switch to issue reset pulses with programmed
duration. 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 LTC2900-1 features
an open-drain RST output, while the LTC2900-2 has a
push-pull RST output.
The 43µA supply current makes the LTC2900 ideal for
power conscious systems and it may be configured to
monitor less than four inputs. The parts are available in
the 10-lead MSOP and the 10-lead 3mm
×
3mm DFN
packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s
s
s
s
s
Desktop and Notebook Computers
Multivoltage Systems
Telecom Equipment
Portable Battery-Powered Equipment
Network Servers
TYPICAL APPLICATIO
Quad Supply Monitor (5V, 3.3V, 2.5V, 1.8V)
5V
3.3V
DC/DC
CONVERTER
2.5V
1.8V
V3
V4
V1
LTC2900-2
V2
V
REF
V
PG
GND
RST
PBR
CRT
C
RT
47nF
t
RST
= 216ms
2900f
C1
0.1µF
C2
0.1µF
R1
59k
1%
R2
40.2k
1%
PUSH-BUTTON
RESET
2900 TA01
U
SYSTEM
LOGIC
U
U
1
LTC2900
ABSOLUTE
AXI U
RATI GS
V1, V2, V3, V4, V
PG
, PBR ............................. – 0.3V to 7V
RST (LTC2900-1)........................................ – 0.3V to 7V
RST (LTC2900-2).......................... – 0.3V to (V2 + 0.3V)
CRT ............................................. – 0.3V to (V
CC
+ 0.3V)
V
REF
............................................. – 0.3V to (V
CC
+ 0.3V)
Reference Load Current (I
VREF
) ............................
±1mA
PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
TOP VIEW
TOP VIEW
V3
V1
CRT
RST
PBR
1
2
3
4
5
10
9
8
7
6
V2
V4
V
REF
V
PG
GND
LTC2900-1CMS
LTC2900-2CMS
LTC2900-1IMS
LTC2900-2IMS
MS PART MARKING
LTYJ
LTYL
LTYK
LTYM
MS PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 250°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
RT50
V
RT33
V
RT30
V
RT25
V
RT18
V
RT15
V
RTA
V
RTAN
V
CC
V
CCMINP
V
REF
V
PG
I
VPG
I
V1
PARAMETER
5V, 5% Reset Threshold
3.3V, 5% Reset Threshold
3V, 5% Reset Threshold
2.5V, 5% Reset Threshold
1.8V, 5% Reset Threshold
1.5V, 5% Reset Threshold
ADJ Reset Threshold
– ADJ Reset Threshold
Minimum Internal Operating Voltage
Minimum Required for Programming
Reference Voltage
Programming Voltage Range
V
PG
Input Current
V1 Input Current
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, unless otherwise noted. (Note 3)
CONDITIONS
V1 Input Threshold
V1, V2 Input Threshold
V2 Input Threshold
V2, V3 Input Threshold
V3, V4 Input Threshold
V3, V4 Input Threshold
V3, V4 Input Threshold
V4 Input Threshold
RST in Correct Logic State,
V
CC
Rising Prior to Program
V
CC
Rising
V
CC
≥
2.3V, I
VREF
=
±1mA,
C
REF
≤
1000pF
V
CC
≥
V
CCMINP
V
PG
= V
REF
V1 = 5V, I
VREF
= 12µA, (Note 4)
q
q
q
q
q
q
q
q
q
q
q
q
q
q
2
U
U
W
W W
U
W
(Notes 1, 2, 3)
V4 Input Current (– ADJ Mode) ............................ – 1mA
Operating Temperature Range
LTC2900-1C/LTC2900-2C ....................... 0°C to 70°C
LTC2900-1I/LTC2900-2I .................... –40°C to 85°C
Storage Temperature Range .................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
ORDER PART
NUMBER
V3
V1
CRT
RST
PBR
1
2
3
4
5
10 V2
9 V4
8 V
REF
7 V
PG
6 GND
LTC2900-1CDD
LTC2900-2CDD
LTC2900-1IDD
LTC2900-2IDD
DD PART MARKING
DD PACKAGE
10-LEAD (3mm
×
3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W
LABU
LABW
LABV
LABX
MIN
4.600
3.036
2.760
2.300
1.656
1.380
0.492
– 18
TYP
4.675
3.086
2.805
2.338
1.683
1.403
0.500
0
MAX
4.750
3.135
2.850
2.375
1.710
1.425
0.508
18
1
2.42
UNITS
V
V
V
V
V
V
V
mV
V
V
V
V
nA
µA
2900f
1.192
0
1.210
1.228
V
REF
±20
43
75
LTC2900
ELECTRICAL CHARACTERISTICS
SYMBOL
I
V2
I
V3
I
V4
PARAMETER
V2 Input Current
V3 Input Current
V4 Input Current
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, unless otherwise noted. (Note 3)
CONDITIONS
V2 = 3.3V
V3 = 2.5V
V3 = 0.55V (ADJ Mode)
V4 = 1.8V
V4 = 0.55V (ADJ Mode)
V4 = –0.05V (–ADJ Mode)
V
CRT
= 0V
V
CRT
= 1.3V
C
RT
= 1500pF
V
X
Less Than Reset Threshold V
RTX
by More Than 1%
I
SINK
= 2.5mA; V1 = 3V, V2 = 3V;
V3, V4 = 0V; V
PG
= 0V
I
SINK
= 100µA; V2 = 1V; V1, V3, V4 = 0V
I
SINK
= 100µA; V1 = 1V; V2, V3, V4 = 0V
V
OH
Output Voltage High RST (LTC2900-1)
(Note 5)
Output Voltage High RST (LTC2900-2)
(Note 6)
Manual Reset Pin
V
IH
V
IL
t
PBW
t
PBD
I
PBR
PBR Input Threshold High
PBR Input Threshold Low
PBR Input Pulse Width
Manual Reset Propagation Delay
PBR Pull-Up Current
V
CC
= 3.3V to 5.5V
V
CC
= 3.3V to 5.5V
V
CC
= 3.3V
V
CC
= 3.3V, V
PBR
Falling
V
PBR
= 0V
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
MIN
TYP
0.8
0.52
MAX
2
1.2
15
0.8
15
15
–2.6
30
9
UNITS
µA
µA
nA
µA
nA
nA
µA
µA
ms
µs
–15
0.34
–15
–15
–1.4
10
5
–2
20
7
150
0.15
0.05
0.05
V2 – 1
0.8 • V2
I
CRT(UP)
I
CRT(DN)
t
RST
t
UV
V
OL
CRT Pull-Up Current
CRT Pull-Down Current
Reset Time-Out Period
V
X
Undervoltage Detect to RST
Output Voltage Low RST
0.4
0.3
0.3
V
V
V
V
V
I
SOURCE
= 1µA
I
SOURCE
= 200µA
1.6
0.4
150
0.1
–10
1
V
V
ns
µs
µA
Note 1:
Absolute Maximum Ratings are those values beyond which the life of
a device may be impaired.
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:
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 5:
The RST output pin on the LTC2900-1 has an internal pull-up to V2
of typically 6µA. However, an external pull-up resistor may be used when
faster rise times are required or for V
OH
voltages greater than V2.
Note 6:
The push-pull RST output pin on the LTC2900-2 is
actively
pulled up
to V2.
TEST CIRCUITS
V1
V2
V3
V4
LTC2900-1 RST
I
SOURCE
1µA
LTC2900-1
V1
V2
V3
V4
2900 F02
RST
I
SINK
2.5mA,
100µA
V1
V2
V3
V4
LTC2900-2 RST
I
SOURCE
200µA
2900 F01
2900 F03
Figure 1. RST V
OH
Test
Figure 2. RST V
OL
Test
Figure 3. Active Pull-Up
RST V
OH
Test
2900f
3
LTC2900
TI I G DIAGRA
V
X
V
RTX
t
UV
t
RST
1.5V
t
PBD
t
RST
RST
PBR
t
PBW
TYPICAL PERFOR A CE CHARACTERISTICS
5V Threshold Voltage
vs Temperature
4.750
THRESHOLD VOLTAGE, V
RT33
(V)
THESHOLD VOLTAGE, V
RT50
(V)
4.725
4.700
4.675
4.650
4.625
4.600
20 40 60
–60 –40 –20 0
TEMPERATURE (°C)
3.115
3.105
3.095
3.085
3.075
3.065
3.055
3.045
THRESHOLD VOLTAGE, V
RT30
(V)
2.5V Threshold Voltage
vs Temperature
2.3750
2.3675
THRESHOLD VOLTAGE, V
RT25
(V)
THRESHOLD VOLTAGE, V
RT18
(V)
2.3600
2.3525
2.3450
2.3375
2.3300
2.3225
2.3150
2.3075
2.3000
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
1.700
1.695
1.690
1.685
1.680
1.675
1.670
1.665
1.660
1.655
–60 –40 –20 0
20 40 60
TEMPERATURE (°C)
80
100
THRESHOLD VOLTAGE, V
RT15
(V)
4
U W
W
Monitor Timing
2900 TD
UW
3.3V Threshold Voltage
vs Temperature
3.135
3.125
2.850
2.840
2.830
2.820
2.810
2.800
2.790
2.780
2.770
80
100
3V Threshold Voltage
vs Temperature
80 100
2900 G01
3.035
–60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
2.760
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
2900 G02
2900 G03
1.8V Threshold Voltage
vs Temperature
1.710
1.705
1.425
1.420
1.415
1.410
1.405
1.400
1.395
1.390
1.385
1.5V Threshold Voltage
vs Temperature
1.380
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
2900 G04
2900 G05
2900 G06
2900f
LTC2900
TYPICAL PERFOR A CE CHARACTERISTICS
ADJ Threshold Voltage
vs Temperature
0.508
THRESHOLD VOLTAGE, V
RTAN
(V)
THRESHOLD VOLTAGE, V
RTA
(V)
0.506
0.504
0.502
0.500
0.498
0.496
0.494
0.492
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
0.018
0.012
0.006
0
–0.006
–0.012
–0.018
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
V
REF
(V)
I
V1
vs Temperature
100
V1 = 5V
90 V2 = 3.3V
V3 = 2.5V
80
V4 = 1.8V
70
I
V1
(µA)
I
V2
(µA)
50
40
30
20
10
0
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
1.0
0.9
0.8
0.7
0.6
0.5
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
I
V3
(µA)
60
I
V4
vs Temperature
1.0
TYPICAL TRANSIENT DURATION (µs)
TYPICAL TRANSIENT DURATION (µs)
V1 = 5V
0.9 V2 = 3.3V
V3 = 2.5V
0.8
V4 = 1.8V
0.7
I
V4
(µA)
0.6
0.5
0.4
0.3
0.2
0.1
0
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
U W
2900 G09
2900 G12
– ADJ Threshold Voltage
vs Temperature
1.228
1.222
1.216
1.210
1.204
1.198
V
REF
vs Temperature
100
80
100
1.192
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
2900 G07
2900 G08
2900 G21
I
V2
vs Temperature
1.5
V1 = 5V
1.4 V2 = 3.3V
V3 = 2.5V
1.3
V4 = 1.8V
1.2
1.1
1.1
I
V3
vs Temperature
V1 = 5V
1.0 V2 = 3.3V
V3 = 2.5V
0.9
V4 = 1.8V
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
2900 G10
2900 G11
Typical Transient Duration
vs Comparator Overdrive (V1, V2)
450
400
350
300
250
200
150
100
50
0
0.1
1
10
100
RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V
RTX
)
2900 G13
Typical Transient Duration
vs Comparator Overdrive (V3, V4)
220
200
180
160
140
120
100
80
60
40
20
0
1
10
100
0.1
RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V
RTX
)
2900 G20
T
A
= 25°C
T
A
= 25°C
RESET OCCURS
ABOVE CURVE
RESET OCCURS
ABOVE CURVE
2900f
5
单片机
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