LTC2902-1CGN [Linear]
Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance; 可编程四通道电源监视器具有可调复位定时器和电源容限
| 型号： | LTC2902-1CGN |
| 厂家： | 
Linear |
| 描述： | Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance |
| 文件： | 总16页 (文件大小：175K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC2902
Programmable Quad Supply
Monitor with Adjustable Reset Timer
and Supply Tolerance
U
FEATURES
DESCRIPTIO
■
Simultaneously Monitors Four Supplies
The LTC®2902 is a programmable supply monitor for sys-
tems with up to four supply voltages. One of 16 preset or
adjustable voltage monitor combinations can be selected
using an external resistor divider connected to the pro-
■
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 gram pin. The preset voltage thresholds are digitally pro-
Voltage Over Temperature
grammable to 5%, 7.5%, 10% or 12.5% below the nomi-
nal operating voltage, and are accurate to 1.5% over tem-
perature. All four voltage comparator outputs are con-
nected to separate pins for individual supply monitoring.
Selectable Supply Tolerance: 5%, 7.5%,
10%, 12.5% Below Monitored Voltage
Low Supply Current: 43µA Typ
Adjustable Reset Time
■
■
■
■
■
■
■
■
The reset delay time is adjustable using an external
capacitor. 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 VCC down to 1V and may be disabled
during supply margin testing. The LTC2902-1 features
an open-drain RST output, while the LTC2902-2 has a
push-pull RST output.
RESET Disable Pin for Margining Applications
Open-Drain RST Output (LTC2902-1)
Push-Pull RST Output (LTC2902-2)
Individual Nondelayed Monitor Outputs for Each Supply
Power Supply Glitch Immunity
Guaranteed RESET for VCC ≥ 1V
U
APPLICATIO S
■
The43µAsupplycurrentmakestheLTC2902idealforpower
conscious systems and the part may be configured to
monitor less than four inputs. The LTC2902-1/LTC2902-2
are available in the 16-lead narrow SSOP package.
Desktop and Notebook Computers
■
Multivoltage Systems
Telecom Equipment
■
■
Portable Battery-Powered Equipment
■
, LTC and LT are registered trademarks of Linear Technology Corporation.
Network Servers
U
TYPICAL APPLICATIO
Quad Supply Monitor with Adjustable Tolerance (5V, 3.3V, 2.5V, 1.8V)
5V
3.3V
2.5V
1.8V
DC/DC
CONVERTER
SYSTEM
LOGIC
3
13
V4
R3
POWER
GOOD
10k
V3
4
2
V1
V2
V
COMP1
COMP2
COMP3
COMP4
RST
16
1
14
15
6
C1
0.1µF
C2
0.1µF
LTC2902-2
12
11
REF
8
RDIS
T0
MARGIN
R1
59k
1%
7
9
TOLERANCE = 5%
= 216ms
V
PG
T1
R2
40.2k
1%
GND
10
CRT
t
RST
5
C
RT
47nF
2902 TA01
2902f
1
LTC2902
W W U W
U W
U
ABSOLUTE AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
(Notes 1, 2, 3)
V1, V2, V3, V4, VPG ..................................... –0.3V to 7V
RST (LTC2902-1)........................................ –0.3V to 7V
RST (LTC2902-2).......................... –0.3V to (V2 + 0.3V)
COMPX, RDIS ............................................. –0.3V to 7V
T0, T1 .......................................... –0.3V to (VCC + 0.3V)
CRT ............................................. –0.3V to (VCC + 0.3V)
ORDER PART
TOP VIEW
NUMBER
COMP3
COMP1
V3
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
COMP2
COMP4
V2
LTC2902-1CGN
LTC2902-2CGN
LTC2902-1IGN
LTC2902-2IGN
V1
V4
CRT
RST
T0
V
REF
V
REF ............................................. –0.3V to (VCC + 0.3V)
V
PG
Reference Load Current (IVREF) ............................ ±1mA
V4 Input Current (–ADJ Mode) ............................ –1mA
Operating Temperature Range
LTC2902-1C/LTC2902-2C ....................... 0°C to 70°C
LTC2902-1I/LTC2902-2I .................... –40°C to 85°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
GN16 PART MARKING
GND
T1
RDIS
29021
29022
29021I
29022I
GN PACKAGE
16-LEAD PLASTIC SSOP
TJMAX = 125°C, θJA = 130°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise noted. (Note 3)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
RT50
V
RT33
V
RT30
V
RT25
V
RT18
V
RT15
V
RTA
5V, 5% Reset Threshold
5V, 7.5% Reset Threshold
5V, 10% Reset Threshold
5V, 12.5% Reset Threshold
V1 Input Threshold
●
●
●
●
4.600
4.475
4.350
4.225
4.675
4.550
4.425
4.300
4.750
4.625
4.500
4.375
V
V
V
V
3.3V, 5% Reset Threshold
3.3V, 7.5% Reset Threshold
3.3V, 10% Reset Threshold
3.3V, 12.5% Reset Threshold
V1, V2 Input Threshold
V2 Input Threshold
●
●
●
●
3.036
2.954
2.871
2.789
3.086
3.003
2.921
2.838
3.135
3.053
2.970
2.888
V
V
V
V
3V, 5% Reset Threshold
3V, 7.5% Reset Threshold
3V, 10% Reset Threshold
3V, 12.5% Reset Threshold
●
●
●
●
2.760
2.685
2.610
2.535
2.805
2.730
2.655
2.580
2.850
2.775
2.700
2.625
V
V
V
V
2.5V, 5% Reset Threshold
2.5V, 7.5% Reset Threshold
2.5V, 10% Reset Threshold
2.5V, 12.5% Reset Threshold
V2, V3 Input Threshold
V3, V4 Input Threshold
V3, V4 Input Threshold
V3, V4 Input Threshold
●
●
●
●
2.300
2.238
2.175
2.113
2.338
2.275
2.213
2.150
2.375
2.313
2.250
2.188
V
V
V
V
1.8V, 5% Reset Threshold
1.8V, 7.5% Reset Threshold
1.8V, 10% Reset Threshold
1.8V, 12.5% Reset Threshold
●
●
●
●
1.656
1.611
1.566
1.521
1.683
1.638
1.593
1.548
1.710
1.665
1.620
1.575
V
V
V
V
1.5V, 5% Reset Threshold
1.5V, 7.5% Reset Threshold
1.5V, 10% Reset Threshold
1.5V, 12.5% Reset Threshold
●
●
●
●
1.380
1.343
1.305
1.268
1.403
1.365
1.328
1.290
1.425
1.388
1.350
1.313
V
V
V
V
ADJ, 5% Reset Threshold
ADJ, 7.5% Reset Threshold
ADJ, 10% Reset Threshold
ADJ, 12.5% Reset Threshold
●
●
●
●
0.492
0.479
0.466
0.453
0.500
0.487
0.473
0.460
0.508
0.494
0.481
0.467
V
V
V
V
2902f
2
LTC2902
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise noted. (Note 3)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
18
UNITS
mV
V
V
–ADJ Reset Threshold
Minimum Internal Operating Voltage
V4 Input Threshold
●
●
–18
0
RTAN
CC
RST, COMPX in Correct Logic State;
1
V
V
V
V
V
Rising Prior to Program
CC
CC
CC
CC
V
V
V
Minimum Required for Programming
Minimum Required for Comparators
Reference Voltage
Rising
Falling
●
●
2.42
2.32
V
V
CCMINP
CCMINC
REF
≥ 2.3V, I
= ±1mA, C ≤ 1000pF
REF
VREF
T0 Low, T1 Low
T0 Low, T1 High
T0 High, T1 Low
●
●
●
●
1.192
1.160
1.128
1.096
1.210
1.178
1.146
1.113
1.228
1.195
1.163
1.130
V
V
V
V
T0 High, T1 High
V
Programming Voltage Range
V
V
≥ V
●
●
●
●
●
0
V
REF
V
nA
µA
µA
PG
VPG
V1
CC
PG
CCMINP
REF
I
I
I
I
V
Input Current
= V
±20
75
2
PG
V1 Input Current
V2 Input Current
V3 Input Current
V1 = 5V, I
V2 = 3.3V
V3 = 2.5V
= 12µA, (Note 4)
43
0.8
VREF
V2
0.52
1.2
15
µA
nA
V3
V3 = 0.55V (ADJ Mode)
–15
I
V4 Input Current
V4 = 1.8V
V4 = 0.55V (ADJ Mode)
V4 = –0.05V (–ADJ Mode)
●
●
●
0.34
0.8
15
15
µA
nA
nA
V4
–15
–15
I
I
t
t
CRT Pull-Up Current
CRT Pull-Down Current
Reset Time-Out Period
V
V
C
= 0V
●
●
●
–1.4
10
–2
20
7
–2.6
30
µA
µA
ms
µs
CRT(UP)
CRT(DN)
RST
CRT
CRT
= 1.3V
= 1500pF
5
9
RT
V Undervoltage Detect to RST or COMPX
X
V Less Than Reset Threshold V
by More Than 1%
150
UV
X
RTX
V
Output Voltage Low RST, COMPX
I
= 2.5mA; V1 = 3V, V2 = 3V;
SINK
●
0.15
0.4
V
OL
V3, V4 = 0V; V = 0V
PG
I
I
= 100µA; V2 = 1V; V1, V3, V4 = 0V
= 100µA; V1 = 1V; V2, V3, V4 = 0V
●
●
0.05
0.05
0.3
0.3
V
V
SINK
SINK
V
V
Output Voltage High RST, COMPX (Note 5)
I
I
= 1µA
●
●
V2 – 1
V
V
OH
OH
SOURCE
SOURCE
Output Voltage High RST (LTC2902-2)
(Note 6)
= 200µA
0.8 • V2
Digital Inputs T0, T1, RDIS
V
V
T0, T1 Low Level Input Voltage
T0, T1 High Level Input Voltage
T0, T1 Input Current
V
V
= 3.3V to 5.5V
= 3.3V to 5.5V
●
●
●
●
●
0.3V
CC
V
V
IL
CC
CC
0.7V
IH
CC
I
T0 = 0V, T1 = V
±0.1
±1
µA
V
INTOL
CC
V
V
RDIS Input Threshold Low
RDIS Input Threshold High
RDIS Pull-Up Current
V
V
V
= 3.3V to 5.5V
0.4
IL
CC
= 3.3V to 5.5V
1.6
V
IH
CC
I
= 0V
–10
µA
RDIS
RDIS
Note 1: Absolute Maximum Ratings are those values beyond which the life of
a device may be impaired.
Note 5: The output pins RST and COMPX have internal pull-ups to V2 of
typically 6µA. However, external pull-up resistors may be used when faster
rise times are required or for V voltages greater than V2.
OH
Note 2: All voltage values are with respect to GND.
Note 6: The push-pull RST output pin on the LTC2902-2 is actively pulled up
to V2.
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.
2902f
3
LTC2902
TEST CIRCUITS
RST
LTC2902-1
LTC2902-2
RST
LTC2902-1
OR COMPX
V1
V2
V3
V4
V1
V2
V3
V4
I
V1
V2
V3
V4
SINK
2.5mA,
RST
OR COMPX
I
I
SOURCE
200µA
SOURCE
100µA
1µA
2902 F02
2902 F03
2902 F01
Figure 1. RST, COMPX VOH Test
Figure 2. RST, COMPX VOL Test
Figure 3. Active Pull-Up RST VOH Test
W U
W
TI I G DIAGRA
VX Monitor Timing
V
RTX
V
X
t
RST
t
UV
1.5V
RST
2902 TD
COMPX
U W
TYPICAL PERFOR A CE CHARACTERISTICS
3.3V Threshold Voltage
vs Temperature
5V Threshold Voltage
vs Temperature
3V Threshold Voltage
vs Temperature
3.135
3.100
3.065
3.030
2.995
2.960
2.925
2.890
2.855
2.820
2.785
2.850
4.75
4.70
4.65
4.60
4.55
4.50
4.45
4.40
4.35
4.30
4.25
5%
7.5%
10%
5%
5%
2.815
2.780
2.745
2.710
2.675
2.640
2.605
7.5%
7.5%
10%
10%
12.5%
12.5%
12.5%
2.570
2.535
–60
20
TEMPERATURE (°C)
60 80
–60
20
TEMPERATURE (°C)
60 80
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
–40 –20
0
40
100
–40 –20
0
40
100
2902 G02
2902 G03
2902 G01
2902f
4
LTC2902
U W
TYPICAL PERFOR A CE CHARACTERISTICS
2.5V Threshold Voltage
vs Temperature
1.8V Threshold Voltage
vs Temperature
1.5V Threshold Voltage
vs Temperature
2.375
2.350
1.710
1.685
1.425
1.405
1.385
1.365
1.345
1.325
1.305
1.285
1.265
5%
7.5%
10%
5%
7.5%
10%
5%
2.325
2.300
1.660
7.5%
10%
2.275
2.250
2.225
2.200
2.175
2.150
2.125
1.635
1.610
1.585
1.560
1.535
1.510
12.5%
12.5%
12.5%
2.100
–60
20
TEMPERATURE (°C)
60 80
–60
20
TEMPERATURE (°C)
60 80
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
–40 –20
0
40
100
–40 –20
0
40
100
2902 G04
2902 G05
2902 G06
ADJ Threshold Voltage
vs Temperature
–ADJ Threshold Voltage
vs Temperature
VREF vs Temperature
0.508
0.503
0.498
0.493
0.488
0.018
0.012
0.006
0
1.228
1.216
1.204
1.192
1.180
1.168
1.156
1.144
1.132
1.112
5%
5%
7.5%
7.5%
10%
0.483
0.478
0.473
0.468
0.463
0.458
0.453
10%
–0.006
–0.012
–0.018
12.5%
12.5%
1.108
1.096
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
–60
20
TEMPERATURE (°C)
60 80
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
–40 –20
0
40
100
2902 G07
2902 G08
2902 G09
IV1 vs Temperature
I
V2 vs Temperature
IV3 vs Temperature
100
90
80
70
60
50
40
30
20
10
0
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
V1 = 5V
V1 = 5V
V1 = 5V
V2 = 3.3V
V3 = 2.5V
V4 = 1.8V
V2 = 3.3V
V3 = 2.5V
V4 = 1.8V
V2 = 3.3V
V3 = 2.5V
V4 = 1.8V
–60
20
TEMPERATURE (°C)
60 80
–60
20
TEMPERATURE (°C)
60 80
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
–40 –20
0
40
100
–40 –20
0
40
100
2902 G10
2902 G11
2902 G12
2902f
5
LTC2902
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Typical Transient Duration
vs Comparator Overdrive (V3, V4)
Typical Transient Duration
vs Comparator Overdrive (V1, V2)
IV4 vs Temperature
220
200
180
160
140
120
100
80
450
400
350
300
250
200
150
100
50
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
T
= 25°C
T
= 25°C
A
V1 = 5V
A
V2 = 3.3V
V3 = 2.5V
V4 = 1.8V
RESET OCCURS
ABOVE CURVE
RESET OCCURS
ABOVE CURVE
60
40
20
0
0.1
0
0.1
1
10
100
1
10
100
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V
)
RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V
)
RTX
RTX
2902 G14
2902 G25
2902 G13
Reset Time-Out Period
vs Temperature
Reset Time-Out Period
vs Capacitance
RST Output Voltage
vs V1, VPG = 0V
10
8.9
5
4
3
2
1
0
T
= 25°C
A
C
= 1500pF
RT
V1 = V2 = V3 = V4
10k PULL-UP FROM RST TO V1
(SILVER MICA)
8.4
7.9
7.4
6.9
6.4
5.9
5.4
4.9
T
= 25°C
1
100m
10m
1m
A
100µ
100n
10p
100p
1n
10n
1µ
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
V1 (V)
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
C
(FARAD)
RT
2902 G17
2902 G15
2902 G16
RST High Level Output Voltage
vs Output Source Current
(LTC2902-2)
RST, COMPX ISINK
vs Supply Voltage
RST, COMPX Voltage Output Low
vs Output Sink Current
10
9
8
7
6
5
4
3
2
1
0
3.0
2.5
2.0
1.5
1.0
0.5
0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
T
= 25°C
V1 = 5V
V2 = 3V
V3 = 2.5V
V4 = 1V
V2 = 3V
V1 = 5V
A
25°C
85°C
–40°C
V
= 0.4V
OL
–40°C
25°C
V
= 0.2V
OL
85°C
0
0.5
1
1.5
(mA)
2
2.5
0
1
3
4
5
6
2
0
10 20 30
50
70 80 90
40
60
V1 OR V2 (V)
I
SOURCE
I
(mA)
SINK
2902 G20
2902 G18
2902 G19
2902f
6
LTC2902
U W
TYPICAL PERFOR A CE CHARACTERISTICS
COMPX Propagation Delay vs
Input Overdrive Above Threshold
COMPX Pull-Up Current
vs V2 (COMPX Held at 0V)
20
18
16
14
12
10
8
250
200
150
100
50
T
= 25°C
A
T = 25°C
A
6
V1, V2
V3, V4
4
2
0
0
1
3
4
4.5
1000
1.5
2
2.5
3.5
5
10
100
V2 (V)
INPUT OVERDRIVE ABOVE THRESHOLD (mV)
2902 G22
2902 G21
RST Pull-Up Current vs V2
(LTC2902-1)
RST Pull-Up Current vs V2
(LTC2902-2)
6
5
4
3
2
1
0
20
18
16
14
12
10
8
T
A
= 25°C
T
= 25°C
A
V
RT33
V
V
RT30
6
RT33
V
RT30
V
RT25
4
V
RT25
2
0
2
2.5
3.5
4
4.5
5
2
2.5
3.5
4
4.5
5
3
3
V2 (V)
V2 (V)
2902 G23
2902 G24
U
U
U
PI FU CTIO S
COMP3 (Pin 1): Comparator Output 3. Nondelayed, active
high logic output with weak pull-up to V2. Pulls high when
V3 is above reset threshold. May be pulled greater than V2
using external pull-up.
V1 (Pin 4): Voltage Input 1. Select from 5V or 3.3V. See
Table 1 for details. The greater of (V1, V2) is also VCC for
the chip. Bypass this pin to ground with a 0.1µF (or
greater) capacitor.
COMP1 (Pin 2): Comparator Output 1. Nondelayed, active
high logic output with weak pull-up to V2. Pulls high when
V1 is above reset threshold. May be pulled greater than V2
using external pull-up.
CRT (Pin 5): Reset Delay Time Programming Pin. Attach
an external capacitor (CRT) to GND to set a reset delay time
of 4.6ms/nF. Leaving the pin open generates a minimum
delay of approximately 50µs. A 47nF capacitor will gener-
ate a 216ms reset delay time.
V3 (Pin 3): Voltage Input 3. Select from 2.5V, 1.8V, 1.5V
or ADJ. See Table 1 for details.
2902f
7
LTC2902
U
U
U
PI FU CTIO S
RST (Pin 6): Reset Logic Output. Active low with weak
pull-up to V2 (LTC2902-1) or active pull-up to V2
(LTC2902-2). Pulls low when any voltage input is below
the reset threshold and held low for programmed delay
time after all voltage inputs are above threshold. May be
pulled above V2 using an external pull-up (LTC2902-1
only).
VREF (Pin 12): Buffered Reference Voltage. A 1.210V
nominal reference used for programming voltage (VPG)
and for the offset of negative adjustable applications. The
buffered reference can source and sink up to 1mA. The
reference can drive a bypass capacitor of up to 1000pF
without oscillation.
V4 (Pin 13): Voltage Input 4. Select from 1.8V, 1.5V, ADJ
or –ADJ. See Table 1 for details.
T0 (Pin 7): Digital Input for Supply Tolerance Selection
(5%, 7.5%, 10% or 12.5%). Used in conjunction with T1
(Pin 9). See Applications Information for tolerance selec-
tion chart (Table 4).
V2 (Pin 14): Voltage Input 2. Select from 3.3V, 3V or 2.5V.
See Table 1 for details. The greater of (V1, V2) is also VCC
forchip.Bypassthispintogroundwitha0.1µF(orgreater)
capacitor. All logic outputs (COMP1, COMP2, COMP3,
COMP4) are weakly pulled up to V2. RST is weakly pulled
up to V2 in the LTC2902-1 and RST is actively pulled up to
V2 in the LTC2902-2.
RDIS (Pin 8): Digital Input for RST Disable. A low input on
this pin forces the RST output to V2 (or pull-up voltage).
Useful for determining supply margins without issuing
reset command to processor. A weak internal pull-up
allows pin to be left floating for normal monitor operation.
COMP4 (Pin 15): Comparator Output 4. Nondelayed,
activehighlogicoutputwithweakpull-uptoV2. Pullshigh
when V4 is above reset threshold. May be pulled greater
than V2 using external pull-up.
T1 (Pin 9): Digital Input for Supply Tolerance Selection
(5%, 7.5%, 10% or 12.5%). Used in conjunction with T0
(Pin 7). See Applications Information for tolerance selec-
tion chart (Table 4).
COMP2 (Pin 16): Comparator Output 2. Nondelayed,
activehighlogicoutputwithweakpull-uptoV2. Pullshigh
when V2 is above reset threshold. May be pulled greater
than V2 using external pull-up.
GND (Pin 10): Ground.
VPG (Pin 11): Voltage Threshold Combination Select
Input. Connect to an external 1% resistive divider be-
tween VREF and GND to select 1 of 16 combinations of
presetand/or±adjustablevoltagethresholds(seeTable 1).
Do not add capacitance on the VPG pin.
2902f
8
LTC2902
W
BLOCK DIAGRA
V1
V2
POWER
DETECT
V
CC
6µA
COMP1
2
–
+
V2
V2
–
+
V1
4
6µA
V2
14
COMP2
16
RESISTIVE
DIVIDER
MATRIX
V3
–
+
3
V4
13
V2
6µA
GND
10
COMP3
1
–
+
V
PG
A/D
11
V2
BUFFER
6µA
V
REF
BANDGAP
REFERENCE
12
COMP4
15
BUFFER
ADJUSTABLE
RESET PULSE
GENERATOR
GAIN
V
ADJUST
CC
V2 LTC2902-1
2µA
6µA
22µA
10µA
RST
6
V
CC
T0
T1
CRT
RDIS
8
7
9
5
C
RT
LTC2902-2
V2
RST
6
2902 DB-1
2902f
9
LTC2902
W U U
U
APPLICATIO S I FOR ATIO
Power-Up
R1
1%
LTC2902
12
11
10
V
REF
On power-up, the larger of V1 or V2 will power the drive
circuits for the RST and the COMPX pins. This ensures
that the RST and COMPX outputs will be low as soon as
V1 or V2 reaches 1V. The RST and COMPX outputs will
remain low until the part is programmed. After program-
ming, ifanyoneoftheVX inputsisbelowitsprogrammed
threshold, RST will be a logic low. Once all the VX inputs
rise above their thresholds, an internal timer is started
and RST is released after the programmed delay time. If
V
PG
R2
GND
1%
2902 F04
Figure 4. Monitor Programming
Table 1. Voltage Threshold Programming
V
PG
MODE V1 (V) V2 (V) V3 (V) V4 (V) R1 (kΩ) R2 (kΩ)
V
REF
0
1
5.0
5.0
3.3
3.3
3.3
5.0
5.0
5.0
5.0
5.0
3.3
3.3
3.3
5.0
5.0
5.0
3.3
3.3
2.5
2.5
2.5
3.3
3.3
3.3
3.0
3.0
2.5
2.5
2.5
3.3
3.3
3.0
ADJ
ADJ
ADJ
ADJ
1.5
2.5
2.5
2.5
2.5
ADJ
1.8
1.8
1.8
1.8
1.8
1.8
ADJ
–ADJ
ADJ
–ADJ
ADJ
ADJ
1.8
Open
93.1
86.6
78.7
71.5
66.5
59.0
53.6
47.5
40.2
34.8
28.0
22.1
16.2
9.53
Short
Short
9.53
16.2
22.1
28.0
34.8
40.2
47.5
53.6
59.0
66.5
71.5
78.7
86.6
93.1
Open
0.000
0.094
0.156
0.219
0.281
0.344
0.406
0.469
0.531
0.594
0.656
0.719
0.781
0.844
0.906
1.000
V
CC < (V3 – 1) and VCC < 2.4V, the V3 input impedance
will be low (1kΩ typ).
2
3
Monitor Programming
4
The LTC2902 input voltage combination is selected by
placing the recommended resistor divider from VREF to
GND and connecting the tap point to VPG, as shown in
Figure 4. Table 1 offers recommended 1% resistor values
for the various modes. The last column in Table 1 speci-
fies optimum VPG/VREF ratios (±0.01) to be used when
programming with a ratiometric DAC.
5
6
7
1.5
8
ADJ
ADJ
1.5
9
10
11
12
13
14
15
ADJ
–ADJ
–ADJ
ADJ
ADJ
During power-up, once V1 or V2 reaches 2.4V (max), the
monitor enters a programming period of approximately
150µs during which the voltage on the VPG pin is sampled
and the monitor is configured to the desired input combi-
nation.DonotaddcapacitancetotheVPG pin.Immediately
after programming, the comparators are enabled and
supply monitoring will begin.
The inverting inputs on the V3 and/or V4 comparators are
setto0.5Vwhenthepositiveadjustablemodesareselected
and with T0 and T1 low (5% tolerance) (Figure 5). The tap
point on an external resistive divider, connected between
thepositivevoltagebeingsensedandground,isconnected
to the high impedance noninverting inputs (V3, V4). The
trip voltage is calculated from:
Supply Monitoring
The LTC2902 is a low power, high accuracy program-
mablequadsupplymonitoringcircuitwithfournondelayed
monitor outputs, a common reset output and selectable
supply thresholds. Reset timing is adjustable using an
externalcapacitor.Singlepinprogrammingselects1of16
input voltage monitor combinations. Two digital inputs
select one of four supply tolerances (5%, 7.5%, 10% or
12.5%). All four voltage inputs must be above predeter-
mined thresholds for the reset not to be invoked. The
LTC2902 will assert the reset and comparator outputs
during power-up, power-down and brownout conditions
on any one of the voltage inputs.
R3
R4
VTRIP = 0.5V 1+
Once the resistor divider is set in the 5% tolerance mode,
there is no need to change the divider for the other
tolerance modes (7.5%, 10%, 12.5%) because the inter-
nal reference is scaled accordingly, moving the trip point
in –2.5% increments.
2902f
10
LTC2902
W U U
APPLICATIO S I FOR ATIO
U
Table 2. Suggested 1% Resistor Values for the ADJ Inputs
V
TRIP
V
(V)
V
(V)
TRIP
R3 (kΩ)
2150
1780
1400
1300
1020
845
R4 (kΩ)
100
100
100
100
100
100
100
100
100
100
100
100
100
100
LTC2902
SUPPLY
R3
1%
12
11.25
9.4
V3 OR V4
+
10
8
R4
1%
7.5
–
7.5
6
7
0.5V
+
5.6
–
5% TOLERANCE MODE
5
4.725
3.055
2.82
2.325
1.685
1.410
1.120
0.933
0.840
3.3
3
511
2902 F05
464
Figure 5. Setting the Positive Adjustable Trip Point
2.5
1.8
1.5
1.2
1
365
237
12
LTC2902
V
REF
182
R4
1%
13 V4
124
–
86.6
68.1
R3
1%
0.9
+
V
TRIP
Table 3. Suggested 1% Resistor Values for the –ADJ Input
2902 F06
V
(V)
V
(V)
TRIP
R3 (kΩ)
187
R4 (kΩ)
121
SUPPLY
–2
–1.87
–4.64
–4.87
–9.31
Figure 6. Setting the Negative Adjustable Trip Point
–5
–5.2
–10
–12
464
121
Inthenegativeadjustablemode, thenoninvertinginputon
the V4 comparator is connected to ground (Figure 6). The
tap point on an external resistive divider, connected be-
tween the negative voltage being sensed and the VREF pin,
is connected to the high impedance inverting input (V4).
VREF provides the necessary level shift required to operate
at ground. The trip voltage is calculated from:
487
121
931
121
–11.30
1130
121
Althoughallfoursupplymonitorcomparatorshavebuilt-in
glitch immunity, bypass capacitors on V1 and V2 are
recommended because the greater of V1 or V2 is also the
VCC for the chip. Filter capacitors on the V3 and V4 inputs
are allowed.
R3
R4
VTRIP = –VREF
; VREF = 1.210V
T0,T1 Low (5% Tolerance Mode)
Power-Down
Once the resistor divider is set in the 5% tolerance mode,
there is no need to change the divider for the other
tolerance modes (7.5%, 10%, 12.5%) because VREF is
scaled accordingly, moving the trip point in –2.5%
increments.
On power-down, once any of the VX inputs drop below
their threshold, RST and COMPX are held at a logic low.
A logic low of 0.4V is guaranteed until both V1 and V2
drop below 1V. If the bandgap reference becomes invalid
(VCC < 2V typ), the part will reprogram once VCC rises
above 2.4V (max).
In a negative adjustable application, the minimum value
forR4islimitedbythesourcingcapabilityofVREF (±1mA).
With no other load on VREF, R4 (minimum) is:
Monitor Output Rise and Fall Time Estimation
All of the outputs (RST, COMPX) have strong pull-down
capability. If the external load capacitance (CLOAD) for a
1.21V ÷ 1mA = 1.21kΩ
Tables 2 and 3 offer suggested 1% resistor values for
various adjustable applications.
2902f
11
LTC2902
W U U
U
APPLICATIO S I FOR ATIO
particular output is known, output fall time (10% to 90%)
is estimated using:
with CRT in Farads and tRST in seconds. The CRT value per
millisecond of delay can also be expressed as CRT/ms =
217 (pF/ms).
t
FALL ≈ 2.2 • RPD • CLOAD
where RPD is the on-resistance of the internal pull-down
transistor. The typical performance curve (VOL vs ISINK
Leaving the CRT pin unconnected will generate a mini-
mum reset time-out of approximately 50µs. Maximum
reset time-out is limited by the largest available low
leakage capacitor. The accuracy of the time-out period will
be affected by capacitor leakage (the nominal charging
current is 2µA) and capacitor tolerance. A low leakage
ceramic capacitor is recommended.
)
demonstrates that the pull-down current is somewhat
linear versus output voltage. Using the 25°C curve, RPD is
estimated to be approximately 40Ω. Assuming a 150pF
load capacitance, the fall time is about 13.2ns.
Although the outputs are considered to be “open-drain,”
theydohaveaweakpull-upcapability(seeCOMPXorRST
Pull-Up Current vs V2 curve). Output rise time (10% to
90%) is estimated using:
Tolerance Programming and the RESET Disable
Using the two digital inputs T0 and T1, the user can
programtheglobalsupplytolerancefortheLTC2902(5%,
7.5%, 10%, 12.5%). The larger tolerances provide more
headroom by lowering the trip thresholds.
tRISE ≈ 2.2 • RPU • CLOAD
where RPU is the on-resistance of the pull-up transistor.
The on-resistance as a function of the V2 voltage at room
temperature is estimated using:
Table 4. Tolerance Programming
T0
T1
TOLERANCE (%)
V
(V)
REF
Low
Low
High
High
Low
High
Low
High
5
1.210
1.178
1.146
1.113
6 •105
V2 – 1
RPU
=
Ω
7.5
10
with V2 = 3.3V, RPU is about 260k. Using 150pF for load
capacitance, the rise time is 86µs. If the output needs to
pull up faster and/or to a higher voltage, a smaller
external pull-up resistor may be used. Using a 10k pull-
up resistor, the rise time is reduced to 3.3µs for a 150pF
load capacitance.
12.5
Under conventional operation, RST and COMPX will go
low when VX is below its threshold. At any time, the RDIS
pin can be pulled low, overriding the reset operation and
forcing the RST pin high. This feature is useful when
determiningsupplymarginsunderprocessorcontrolsince
the reset command will not be invoked. The RDIS pin is
connected to a weak internal pull-up to VCC (10µA typ),
allowing the pin to be left floating if unused.
The LTC2902-2 has an active pull-up to V2 on the RST
output. The typical performance curve (RST Pull-Up Cur-
rent vs V2 curve) demonstrates that the pull-up current is
somewhat linear versus the V2 voltage and RPU is esti-
mated to be approximately 625Ω. A 150pF load capaci-
tance makes the rise time about 206ns.
Ensuring RST Valid for VCC Down to 0V (LTC2902-2)
When VCC is below 1V the RST pull-down capability is
drastically reduced. The RST pin may float to undeter-
mined voltages when connected to high impedance (such
as CMOS logic inputs). The addition of a pull-down resis-
tor from RST to ground will provide a path for stray charge
and/or leakage currents. The resistor value should be
small enough to provide effective pull-down without ex-
cessively loading the pull-up circuitry. Too large a value
may not pull down well enough. A 100k resistor from RST
to ground is satisfactory for most applications.
2902f
Selecting the Reset Timing Capacitor
The reset time-out period is adjustable in order to accom-
modate a variety of microprocessor applications. The
reset time-out period, tRST, is adjusted by connecting a
capacitor,CRT,betweentheCRTpinandground.Thevalue
of this capacitor is determined by:
CRT = tRST • 217 • 10–9
12
LTC2902
U
TYPICAL APPLICATIO S
Quad Supply Monitor, 5% Tolerance
5V, 3V, 1.8V, 12V (ADJ)
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
COMP3 COMP2
COMP1 COMP4
R3
2.15M
1%
1.8V
5V
V3
V2
V4
3V
LTC2902
V1
12V
V
= 11.25V
TRIP
CRT
RST
T0
V
REF
SYSTEM
RESET
R4
100k
1%
V
PG
GND
T1
C
RT
RDIS
2902 TA02
5V, –5V Monitor with Unused V2, V3 Inputs Pulled
Above Trip Thresholds (5% Tolerance)
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
COMP3 COMP2
COMP1 COMP4
R3
464k
1%
V3
V2
V4
5V
LTC2902
V1
–5V
V
TRIP
= –4.64V
CRT
RST
T0
V
REF
R1
16.2k
1%
R4
121k
1%
SYSTEM
RESET
V
PG
GND
T1
C
RT
R2
86.6k
1%
RDIS
2902 TA03
2902f
13
LTC2902
TYPICAL APPLICATIO S
U
Quad Supply Monitor with LED Undervoltage Indicators,
12.5% Tolerance, Reset Disabled
5V, 3.3V, 2.5V, 1.5V
R
R
R
R
L4
1k
L1
L3
L2
1k
1k
1k
LED
LED
LED
LED
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
COMP3 COMP2
COMP1 COMP4
2.5V
3.3V
1.5V
V3
V2
V4
5V
LTC2902
V1
CRT
RST
T0
V
REF
R1
V
PG
53.6k
1%
GND
T1
C
R2
47.5k
1%
RT
RDIS
2902 TA04
2902f
14
LTC2902
U
PACKAGE DESCRIPTIO
GN Package
16-Lead Plastic SSOP (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1641)
.189 – .196*
(4.801 – 4.978)
.045 ±.005
.009
(0.229)
REF
16 15 14 13 12 11 10 9
.254 MIN
.150 – .165
.229 – .244
.150 – .157**
(5.817 – 6.198)
(3.810 – 3.988)
.0165 ±.0015
.0250 TYP
RECOMMENDED SOLDER PAD LAYOUT
1
2
3
4
5
6
7
8
.015 ± .004
(0.38 ± 0.10)
× 45°
.053 – .068
(1.351 – 1.727)
.004 – .0098
(0.102 – 0.249)
.007 – .0098
(0.178 – 0.249)
0° – 8° TYP
.016 – .050
(0.406 – 1.270)
.0250
(0.635)
BSC
.008 – .012
(0.203 – 0.305)
NOTE:
1. CONTROLLING DIMENSION: INCHES
INCHES
2. DIMENSIONS ARE IN
(MILLIMETERS)
GN16 (SSOP) 0502
3. DRAWING NOT TO SCALE
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
2902f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
15
LTC2902
U
TYPICAL APPLICATIO
Quad Supply Monitor with Hysteresis
5% Tolerance (Supplies Rising)
12.5% Tolerance (After RST Goes High)
5V
LTC2902-1
4
14
3
2
V1
COMP1
COMP2
COMP3
COMP4
RST
16
1
3.3V
2.5V
1.8V
V2
10k
V3
13
8
15
6
V4
RDIS
12
11
10
7
V
V
T0
REF
PG
R1
9
T1
59k
1%
R2
40.2k
1%
5
GND
CRT
C
RT
2902 TA05
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC690
5V Supply Monitor, Watchdog Timer and Battery Backup
3.3V Supply Monitor, Watchdog Timer and Battery Backup
5V Supply Monitor and Watchdog Timer
4.65V Threshold
LTC694-3.3
LTC699
2.9V Threshold
4.65V Threshold
LTC1232
5V Supply Monitor, Watchdog Timer and Push-Button Reset
4.37V/4.62V Threshold
4.725V, 3.118V, 1V Thresholds (±0.75%)
LTC1326
Micropower Precision Triple Supply Monitor for 5V, 3.3V and ADJ
LTC1326-2.5
LTC1536
Micropower Precision Triple Supply Monitor for 2.5V, 3.3V and ADJ 2.363V, 3.118V, 1V Thresholds (±0.75%)
Precision Triple Supply Monitor for PCI Applications
Micropower Triple Supply Monitor for 2.5V, 3.3V and ADJ
Micropower Triple Supply Monitor for 5V, 3.3V and ADJ
Meets PCI t
Timing Specifications
FAIL
LTC1726-2.5
LTC1726-5
Adjustable RESET and Watchdog Time-Outs
Adjustable RESET and Watchdog Time-Outs
Individual Monitor Outputs in MSOP
5-Lead SOT-23 Package
LTC1727-2.5/LTC1727-5 Micropower Triple Supply Monitor with Open-Drain Reset
LTC1728-1.8/LTC1728-3.3 Micropower Triple Supply Monitor with Open-Drain Reset
LTC1728-2.5/LTC1728-5 Micropower Triple Supply Monitor with Open-Drain Reset
5-Lead SOT-23 Package
LTC1985-1.8
LTC2900
Micropower Triple Supply Monitor with Push-Pull Reset Output
Programmable Quad Supply Monitor
5-Lead SOT-23 Package
Adjustable RESET, 10-Lead MSOP Package
LTC2901
Programmable Quad Supply Monitor
Adjustable RESET and Watchdog Timer,
16-Lead SSOP Package
2902f
LT/TP 1002 2K • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
LINEAR TECHNOLOGY CORPORATION 2002
相关型号：
LTC2902-1CGN#PBF
LTC2902 - Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance; Package: SSOP; Pins: 16; Temperature Range: 0°C to 70°C
Linear
LTC2902-1CGN#TRPBF
LTC2902 - Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance; Package: SSOP; Pins: 16; Temperature Range: 0°C to 70°C
Linear
LTC2902-1IGN
Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance
Linear System
LTC2902-1IGN
Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance
Linear
LTC2902-1IGN#PBF
LTC2902 - Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance; Package: SSOP; Pins: 16; Temperature Range: -40°C to 85°C
Linear
LTC2902-1IGN#TR
LTC2902 - Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance; Package: SSOP; Pins: 16; Temperature Range: -40°C to 85°C
Linear
LTC2902-1IGN#TRPBF
LTC2902 - Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance; Package: SSOP; Pins: 16; Temperature Range: -40°C to 85°C
Linear
LTC2902-2CGN
Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance
Linear System
LTC2902-2CGN
Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance
Linear
LTC2902-2CGN#PBF
LTC2902 - Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance; Package: SSOP; Pins: 16; Temperature Range: 0°C to 70°C
Linear
LTC2902-2CGN#TR
LTC2902 - Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance; Package: SSOP; Pins: 16; Temperature Range: 0°C to 70°C
Linear
LTC2902-2CGN#TRPBF
LTC2902 - Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance; Package: SSOP; Pins: 16; Temperature Range: 0°C to 70°C
Linear
©2020 ICPDF网 联系我们和版权申明