LINER LTC2930HDD-PBF Confi gurable six supply monitor with adjustable reset timer, manual reset Datasheet

LTC2930
Configurable Six Supply
Monitor with Adjustable
Reset Timer, Manual Reset
DESCRIPTION
FEATURES
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Simultaneously Monitors Six Supplies
16 User Selectable Combinations of
5V, 3.3V, 3V, 2.5V, 1.8V, 1.5V and
± Adjustable Voltage Thresholds
Guaranteed ±1.5% Threshold Accuracy
Adjustable Reset Timeout
Low Supply Current: 52μA
Manual Reset Pin
Power Supply Glitch Immunity
Guaranteed RST for VCC ≥ 1V
High Temperature Operation to 125°C
12-Lead 3mm × 3mm DFN Package
The LTC®2930 is a configurable supply monitor for
systems with up to six supply voltages. One of 16 preset or
adjustable voltage monitor combinations can be selected
using an external resistive divider connected to the mode
select pin. The preset voltage thresholds are accurate
to ±1.5% over temperature. The LTC2930 also features
adjustable inputs with a 0.5V nominal threshold.
The reset timeout period is adjustable using an external
capacitor. A reset event may be generated with a manual
reset button on the manual reset input. 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 externally pulled up to an external voltage.
APPLICATIONS
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Desktop and Notebook Computers
Multivoltage Systems
Telecom Equipment
Portable Battery-Powered Equipment
Network Servers
Automotive
The 52μA supply current makes the LTC2930 ideal for
power conscious systems and it may be configured to
monitor fewer than six inputs.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6967591, 7119714, 7239251.
TYPICAL APPLICATION
Six Supply Monitor, 5% Threshold
12V, 5V, 3.3V, 1.8V, 1.2V, –5.2V
Voltage Threshold Configuration Table
12V
V1 (V)
V2 (V)
V3 (V)
V4 (V)
V5 (V)
5.0
3.3
2.5
1.8
ADJ
ADJ
5.0
3.3
2.5
1.5
ADJ
ADJ
5.0
3.3
2.5
ADJ
ADJ
ADJ
5.0
3.3
1.8
ADJ
ADJ
ADJ
5.0
3.3
1.8
–ADJ
ADJ
ADJ
5.0
3.3
ADJ
ADJ
ADJ
ADJ
5.0
3.3
ADJ
–ADJ
ADJ
ADJ
5.0
3.0
2.5
ADJ
ADJ
ADJ
V5
5.0
3.0
1.8
ADJ
ADJ
ADJ
V6
5.0
3.0
ADJ
ADJ
ADJ
ADJ
3.3
2.5
1.8
1.5
ADJ
ADJ
3.3
2.5
1.8
ADJ
ADJ
ADJ
3.3
2.5
1.8
–ADJ
ADJ
ADJ
3.3
2.5
1.5
ADJ
ADJ
ADJ
3.3
2.5
ADJ
ADJ
ADJ
ADJ
3.3
2.5
ADJ
–ADJ
ADJ
ADJ
5V
3.3V
1.8V
SYSTEM
LOGIC
1.2V
–5.2V
2150k
1%
487k
1%
V1
V2
0.1μF
V3
124k
1%
V4
121k
1%
100k
1%
100k
1%
16.2k
1%
86.6k
1%
RST
LTC2930
MR
VREF
VPG
GND
CRT
MANUAL RESET
CRT
47nF
2930 TA01
tRST = 94ms
V6 (V)
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LTC2930
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Notes 1, 2, 3)
V1, V2, V3, V4, V5, V6, VPG, RST................ –0.3V to 7V
CRT, VREF, MR...............................–0.3V to (VCC + 0.3V)
Reference Load Current (IVREF) ..............................±1mA
V4 Input Current (–ADJ Mode) ..............................–1mA
RST Current .........................................................±10mA
Operating Temperature Range
LTC2930C ................................................ 0°C to 70°C
LTC2930I.............................................. –40°C to 85°C
LTC2930H .......................................... –40°C to 125°C
Storage Temperature Range................... –65°C to 150°C
TOP VIEW
12 V6
V5
1
V3
2
V1
3
CRT
4
9 VREF
RST
5
8 VPG
MR
6
7 GND
11 V2
10 V4
13
DD PACKAGE
12-LEAD (3mm × 3mm) PLASTIC DFN
TJMAX = 130°C, θJA = 43°C/W
EXPOSED PAD (PIN 13) IS GND
(PCB CONNECTION OPTIONAL)
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC2930CDD#PBF
LTC2930CDD#TRPBF
LDMJ
12-Lead 3mm × 3mm DFN
0°C to 70°C
LTC2930IDD#PBF
LTC2930IDD#TRPBF
LDMJ
12-Lead 3mm × 3mm DFN
–40°C to 85°C
LTC2930HDD#PBF
LTC2930HDD#TRPBF
LDMJ
12-Lead 3mm × 3mm DFN
–40°C to 125°C
*The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
This product is only offered in trays. For more information go to: http://www.linear.com/packaging/
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 specified. (Note 3)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
VCC
Minimum Internal Operating Voltage
RST in Correct Logic State
●
VCCMINP
Minimum Required for Mode Selection
VCC Rising
●
VRT50
5V, 5% Reset Threshold
V1 Input Threshold
●
4.600
4.675
VRT33
3.3V, 5% Reset Threshold
V1, V2 Input Threshold
●
3.036
3.086
3.135
V
VRT30
3V, 5% Reset Threshold
V2 Input Threshold
●
2.760
2.805
2.850
V
VRT25
2.5V, 5% Reset Threshold
V2, V3 Input Threshold
●
2.300
2.338
2.375
V
VRT18
1.8V, 5% Reset Threshold
V3, V4 Input Threshold
●
1.656
1.683
1.710
V
1
V
2.4
V
4.750
V
VRT15
1.5V, 5% Reset Threshold
V3, V4 Input Threshold
●
1.380
1.403
1.425
V
VRTA
ADJ Reset Threshold
V3, V4, V5, V6 Input Threshold
●
492.5
500
507.5
mV
VRTAN
–ADJ Reset Threshold
V4 Input Threshold
●
–18
0
18
mV
VREF
Reference Voltage
VCC ≥ 2.3V, IVREF = ±1mA, CREF ≤ 1000pF
●
1.192
1.210
1.228
V
VPG
Mode Selection Voltage Range
VCC ≥ VCCMINP
●
0
VREF
V
VPG = VREF
●
±20
nA
IVPG
VPG Input Current
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LTC2930
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 specified. (Note 3)
SYMBOL
PARAMETER
CONDITIONS
MIN
IV1
V1 Input Current
V1 = 5V, IVREF = 12μA (Note 4)
●
TYP
MAX
52
75
UNITS
μA
IV2
V2 Input Current
V2 = 3.3V
●
0.8
2
μA
IV3
V3 Input Current
V3 = 2.5V
V3 = 0.55V (ADJ Mode)
●
●
0.52
1.2
±15
μA
nA
IV4
V4 Input Current
V4 = 1.8V
V4 = 0.55V (ADJ Mode)
V4 = –0.02V (–ADJ Mode)
●
●
●
0.34
0.8
±15
±15
μA
nA
nA
IV5, IV6
V5, V6 Input Current
V5, V6 = 0.55V
●
±15
nA
ICRT(UP)
CRT Pull-Up Current
VCRT = GND
●
–1.4
–2
–2.6
μA
ICRT(DN)
CRT Pull-Down Current
VCRT = 1.3V
●
10
20
30
μA
●
2
3
4
ms
tRST
Reset Timeout Period
CRT = 1500pF
tUV
Vn Undervoltage Detect to RST
Vn Less Than Reset Threshold by More
than 1%
VOL
Voltage Output Low RST
ISINK = 3mA, VCC = 3V
ISINK = 100μA, VCC = 1V
●
●
VOH
Voltage Output High RST (Note 5)
ISOURCE = –1μA
●
VIL
MR Input Threshold Low
VCC = 3.3V to 5.5V
●
VIH
MR Input Threshold High
VCC = 3.3V to 5.5V
●
1.6
V
tMRW
MR Input Pulse Width
VCC = 3.3V
●
150
ns
tMRD
Manual Reset Propagation Delay
VCC = 3.3V, VMR Falling
●
IMR
MR Pull-Up Current
VMR = 1V
●
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: 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 (VCC).
150
0.15
0.05
μs
0.4
0.3
V2-1
V
0.4
–4
V
V
V
0.1
1
μs
–10
–16
μA
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 output pin RST has a diode protected 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 VOH voltages greater than V2.
TIMING DIAGRAM
Vn Monitor Timing
Vn
VRT
tUV
tRST
tMRD
tRST
RST
2930 TD
MR
tMRW
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LTC2930
TYPICAL PERFORMANCE CHARACTERISTICS
–ADJ Threshold Voltage
vs Temperature
1.010
1.005
1.000
0.995
0.990
0.985
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
VREF vs Temperature
18
1.228
12
1.222
6
1.216
VREF (V)
1.015
THRESHOLD VOLTAGE, VRTAN (mV)
NORMALIZED THRESHOLD VOLTAGES (V/V)
Normalized Threshold Voltages
vs Temperature
0
–6
1.204
–12
1.198
–18
–50 –25
125
50
25
75
0
TEMPERATURE (°C)
100
2930 G01
TYPICAL TRANSIENT DURATION (μs)
300
125°C
IV4 (A)
–1μ
–100n
50
–10n
45
–1n
90°C
25°C
100
125
–100p
–300
–250
–200
–150 –100
V4 (mV)
–50
250
200
RESET OCCURS ABOVE CURVE
150
100
50
0
0
0.1
1
10
100
RESET COMPARATOR OVERDRIVE (% OF VRTX)
2930 G05
2930 G06
RST Output Voltage
vs V1, VPG = GND
5
TA = 25°C
10k PULL-UP FROM RST TO V1
5
375
RESET OCCURS ABOVE CURVE
225
150
75
RST OUTPUT VOLTAGE (V)
TYPICAL TRANSIENT DURATION (μs)
6
TA = 25°C
Reset Timeout Period
vs Temperature
RESET TIMEOUT PERIOD, tRST (ms)
Transient Duration vs Comparator
Overdrive (V3, V4, V5, V6)
300
4
3
2
1
0
0
0.1
1
10
100
RESET COMPARATOR OVERDRIVE (% OF VRTX)
2930 G07
125
TA = 25°C
2930 G04
450
100
Transient Duration vs Comparator
Overdrive (V1,V2)
–10μ
55
50
25
75
0
TEMPERATURE (°C)
2930 G03
–100μ
V1 = 5V
V2 = 3.3V
65 V3 = 2.5V
V4 = 1.8V
V5 = V6 = 1V
60
50
25
75
0
TEMPERATURE (°C)
1.192
–50 –25
I(V4) vs V4 in Negative
Adjust Mode
70
SUPPLY CURRENT, IV1 (μA)
125
2930 G02
Supply Current vs Temperature
40
–50 –25
1.210
0
1
2
3
4
5
V1 (V)
2930 G08
CRT = 1500pF
(SILVER MICA)
4
3
2
1
–50
–25
75
0
25
50
TEMPERATURE (°C)
100
125
2930 G09
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LTC2930
TYPICAL PERFORMANCE CHARACTERISTICS
ISINK vs Supply Voltage (RST)
Reset Timeout Period vs CRT
15
TA = 25°C
1
TA = 25°C
12
VOL = 0.4V
100m
ISINK (mA)
RESET TIMEOUT PERIOD tRST (s)
10
10m
9
VOL = 0.2V
6
1m
3
100μ
10μ
10p
100p
1n
10n
CRT (F)
100n
0
1μ
1
0
2930 G10
3
2
V1 OR V2 (V)
4
5
2930 G11
Voltage Output Low
vs Output Sink Current (RST)
500
RST Pull-Up Current vs V2
18
V1 = 5V
V2 = 3V
125°C
15
PULL-UP CURRENT (μA)
400
VOL (mV)
85°C
300
25°C
200
–40°C
100
0
TA = 25°C
12
9
VRT33
VRT30
6
3 VRT25
0
0
2
6
4
ISINK (mA)
8
10
2930 G12
2.0
2.5
3.0
3.5
V2 (V)
4.0
4.5
5.0
2930 G13
PIN FUNCTIONS
V5 (Pin 1): Adjustable Voltage Input 5. High impedance
comparator input with 0.5V typical threshold. See
Applications Information for details. Tie to V1 if unused.
V3 (Pin 2): Voltage Input 3. Select from 2.5V, 1.8V, 1.5V,
or ADJ. See Applications Information for details. Tie to
V1 if unused.
V1 (Pin 3): Voltage Input 1. Select from 5V or 3.3V. See
Applications Information for details. The greater of V1 or
V2 is also VCC for the device. Bypass this pin to ground
with a 0.1μF (or greater) capacitor.
CRT (Pin 4): Reset Timeout Capacitor. Attach an external
capacitor (CRT) to GND to set a reset timeout of 2ms/nF.
Leaving the pin open generates a minimum delay of
approximately 25μs. A 47nF capacitor generates a 94ms
reset delay time.
RST (Pin 5): Reset Output. Logic output with weak 6μA
pull-up to V2. Pulls low when any voltage input is below
the reset threshold and held low for the configured delay
time after all voltage inputs are above threshold. Use an
external pull-up to pull greater than V2. Leave open if
unused.
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LTC2930
PIN FUNCTIONS
MR (Pin 6): Manual Reset Input. A logic low on this
pin pulls RST low. When the MR pin returns high, RST
returns high after the configured reset timeout if all six
voltage inputs are above threshold. A weak internal pull-up
allows the pin to be left open for normal monitor operation.
When using a switch, the switch is debounced through
the reset circuitry using the delay provided by the CRT
timing capacitor.
GND (Pin 7): Ground.
VPG (Pin 8): Threshold Select Input. Connect to an external
1% resistive divider between VREF and GND to select 1
of 16 combinations and/or ±adjustable voltage thresholds
(See Table 1). Do not add capacitance on the VPG pin.
VREF (Pin 9): Buffered Reference Voltage Output. A
1.210V nominal reference used for the mode selection
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 10): Voltage Input 4. Select from 1.8V, 1.5V, ADJ
or –ADJ. See Applications Information for details. Tie to
V1 if unused.
V2 (Pin 11): Voltage Input 2. Select from 3.3V, 3V or 2.5V.
See Applications Information for details. The greater of V1,
V2 is also VCC for the device. Bypass this pin to ground
with a 0.1μF (or greater) capacitor. RST is weakly pulled
up to V2.
V6 (Pin 12): Adjustable Voltage Input 6. High impedance
comparator input with 0.5V typical threshold. See
Applications Information for details. Tie to V1 if unused.
Exposed Pad (Pin 13): Exposed pad may be left open or
connected to device ground.
BLOCK DIAGRAM
BUFFER
VREF
9
1.210V
BANDGAP
REFERENCE
VPG
8
V1
A/D
POWER
DETECT
V1
VCC
3
V2
11
V3
2
RESISTIVE
DIVIDER
MATRIX
4
–
4
+
V2
CMP1-4
V4
10
V5
–
1
+
V2
CMP5
6μA
0.5V
RST
+
ADJUSTABLE
RESET PULSE
GENERATOR
CMP6
V6
12
4
–
5
VCC
2μA
10μA
GND
7
22μA
VCC
6 MR
4 CRT
CRT
2931 BD
2930fa
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LTC2930
APPLICATIONS INFORMATION
Supply Monitoring
Table 1. Voltage Threshold Modes*
The LTC2930 is a low power, high accuracy configurable six
supply monitoring circuit with a common reset output. An
external capacitor sets the reset timeout period. An external
resistive divider between VREF, VPG and GND selects 1 of
16 possible input voltage monitor combinations. All six voltage inputs must be above their predetermined thresholds
for the reset not to be activated. The LTC2930 asserts the
reset output during power-up, power-down and brownout
conditions on any one of the voltage inputs.
Power-Up
The greater of V1 and V2 serves as the internal supply
voltage (VCC). On power-up, VCC powers the drive circuits
for the RST pin. This ensures that the RST output will be
low as soon as either V1 or V2 reaches 1V. The RST output
remains low until the part is configured. Once voltage
thresholds are set, if any of the supply monitor inputs is
below its configured threshold, RST will be a logic low.
Once all the monitor inputs rise above their thresholds,
an internal timer is started and RST is released after the
delay time. If VCC < (V3 – 1.0V) and VCC < 2.4V, the V3
input impedance will be low (10kΩ typical).
Threshold Accuracy
Consider a 5V system with ±5% tolerance. The 5V supply
may vary between 4.75V to 5.25V. System ICs powered by
this supply must operate reliably within this band (and a
little more as explained below). A perfectly accurate su5V
SUPPLY TOLERANCE
MINIMUM
RELIABLE
SYSTEM
VOLTAGE
IDEAL
SUPERVISOR
THRESHOLD
4.75V
±1.5%
THRESHOLD
BAND
NOMINAL
SUPPLY
VOLTAGE
–5%
4.675V
–6.5%
4.6V
–8%
REGION OF POTENTIAL MALFUNCTION
Figure 1. 1.5% Threshold Accuracy Improves System Reliability
MODE V1 (V) V2 (V) V3 (V) V4 (V) R1 (kΩ) R2 (kΩ)
VPG
VREF
0
5.0
3.3
ADJ
ADJ
Open
Short
0.000
1
5.0
3.3
ADJ
–ADJ
93.1
9.53
0.094
2
3.3
2.5
ADJ
ADJ
86.6
16.2
0.156
3
3.3
2.5
ADJ
–ADJ
78.7
22.1
0.219
4
3.3
2.5
1.5
ADJ
71.5
28.0
0.281
5
5.0
3.3
2.5
ADJ
66.5
34.8
0.344
6
5.0
3.3
2.5
1.8
59.0
40.2
0.406
7
5.0
3.3
2.5
1.5
53.6
47.5
0.469
8
5.0
3.0
2.5
ADJ
47.5
53.6
0.531
9
5.0
3.0
ADJ
ADJ
40.2
59.0
0.594
10
3.3
2.5
1.8
1.5
34.8
66.5
0.656
11
3.3
2.5
1.8
ADJ
28.0
71.5
0.719
12
3.3
2.5
1.8
–ADJ
22.1
78.7
0.781
13
5.0
3.3
1.8
–ADJ
16.2
86.6
0.844
14
5.0
3.3
1.8
ADJ
9.53
93.1
0.906
15
5.0
3.0
1.8
ADJ
Short
Open
1.000
*V5 and V6 are always adjustable (ADJ).
pervisor for this supply generates a reset at exactly 4.75V,
however no supervisor is this perfect. The actual reset
threshold of a supervisor varies over a specified band;
the LTC2930 varies ±1.5% around its nominal threshold
voltage (see Figure 1) over temperature.
The reset threshold band and the power supply tolerance
bands should not overlap. This prevents false or nuisance
resets when the power supply is actually within its specified tolerance band.
The LTC2930 has a ±1.5% reset threshold accuracy, so a
“5%” threshold is typically set to 6.5% below the nominal
input voltage. Therefore, a typical 5V, “5%” threshold is
4.675V. The threshold is guaranteed to lie in the band between 4.750V and 4.600V over temperature. The powered
system must work reliably down to the low end of the
threshold band, or risk malfunction before a reset signal
is properly issued.
A less accurate supervisor increases the required system
voltage margin and increases the probability of system
malfunction. The LTC2930 ±1.5% specification improves
the reliability of the system over supervisors with wider
threshold tolerances.
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LTC2930
APPLICATIONS INFORMATION
Table 2. Suggested 1% Resistor Values for the ADJ Inputs
R1
1%
LTC2930
VREF
VPG
GND
R2
1%
2930 F02
Figure 2. Mode Selection
Monitor Configuration
Select the LTC2930 input voltage combination by placing
the recommended resistive divider from VREF to GND and
connecting the tap point to VPG, as shown in Figure 2.
Table 1 offers recommended 1% resistor values for each
of the 16 modes. The last column in Table 1 specifies
optimum VPG/VREF ratios (± 0.01), when configuring with
a ratiometric DAC.
At power-up, once V1 or V2 reaches 2.4V, the monitor
enters a setup period of approximately 150μs. During the
setup time, the voltage on the VPG pin is sampled and the
monitor is configured to the desired input combination. The
comparators are enabled and supply monitoring begins.
Do not add capacitance to the VPG pin.
VTRIP
LTC2930
R3
1%
V3, V4, V5 OR V6
R4
1%
VSUPPLY (V)
VTRIP (V)
R3 (kΩ)
R4 (kΩ)
12
11.25
2150
100
10
9.4
1780
100
8
7.5
1400
100
7.5
7
1300
100
6
5.6
1020
100
5
4.725
845
100
3.3
3.055
511
100
3
2.82
464
100
2.5
2.325
365
100
1.8
1.685
237
100
1.5
1.410
182
100
1.2
1.120
124
100
1
0.933
86.6
100
0.9
0.840
68.1
100
*See Figure 3.
Table 3. Suggested 1% Resistor Values for the –ADJ Inputs
VSUPPLY (V)
VTRIP (V)
R3 (kΩ)
R4 (kΩ)
–2
–1.87
187
121
–5
–4.64
464
121
–5.2
–4.87
487
121
–10
–9.31
931
121
–12
–11.30
1130
121
*See Figure 4.
+
–
R3 VTRIP = 0.5V • 1+ R4 0.5V
2930 F03
Figure 3. Setting the Positive Adjustable Trip Point
Using The Adjustable Thresholds
The reference inputs on the V3 and/or V4 comparators
are set to 0.5V when the positive adjustable modes are
selected (Figure 3). The reference inputs on the V5 and V6
comparators are always set to 0.5V. The tap point on an
external resistive divider, connected between the positive
voltage being sensed and ground, is connected to the high
impedance, adjustable inputs (V3, V4, V5, V6). Calculate
the trip voltage from:
In the negative adjustable mode, the reference level on the
V4 comparator is connected to ground (Figure 4). The tap
point on an external resistive divider, connected between
the negative voltage being sensed and the VREF pin, is
VREF
LTC2930
R4
1%
V4
R3
1%
VTRIP
2930 F04
Figure 4. Setting the Negative Adjustable Trip Point
2930fa
8
LTC2930
APPLICATIONS INFORMATION
connected to the high impedance adjustable input (V4).
VREF provides the necessary level shift required to operate
at ground. The negative trip voltage is calculated from:
VTRIP = −VREF •
R3
;V = 1.210V Nominal
R4 REF
In a negative adjustable application, the minimum value for
R4 is limited by the sourcing capability of VREF (±1mA).
With no other load on VREF, R4 (minimum) is:
1.210V
= 1.210k
1mA
Tables 2 and 3 offer suggested 1% resistor values for various positive and negative supply adjustable applications
assuming 5% monitor thresholds.
Although all six supply monitor comparators have builtin glitch immunity, bypass capacitors on V1 and V2 are
recommended because the greater of V1 or V2 is also the
VCC for the device. Filter capacitors on the V3, V4, V5 and
V6 inputs are allowed.
Power-Down
On power-down, once any of the monitor inputs drops
below its threshold, RST is 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
typical), the LTC2930 will enter the 150μs setup period
when VCC rises above 2.4V max.
Selecting the Reset Timing Capacitor
The reset timeout period is adjustable in order to
accommodate a variety of microprocessor applications.
The reset timeout period, tRST, is adjusted by connecting
a capacitor, CRT, between the CRT pin and ground. The
value of this capacitor is determined by:
CRT =
tRST
= 500 [pF / ms] • tRST
2MΩ
Leaving the CRT pin unconnected generates a minimum
reset timeout of approximately 25μs. Maximum reset
timeout is limited by the largest available low leakage
capacitor. The accuracy of the timeout period is affected
by capacitor leakage (the nominal charging current is 2μA)
and capacitor tolerance. A low leakage ceramic capacitor
is recommended.
OR-ed System Reset
In Figure 5, two LTC2930s are configured to monitor 11
supply voltages simultaneously. The unused adjustable
input pin is tied to the V1 input. The open-drain RST
outputs are OR-tied and pulled up to 5V through a 10kΩ
resistor. RST pulls high 94ms after all the inputs are above
the threshold voltages. Should a reset event occur on either LTC2930, both RST outputs pull low. Similarly, if the
manual reset pushbutton is pressed, both RST outputs
also pull low.
Using a Pushbutton On/Off Controller with the
LTC2930
In Figure 6, the LTC2950-1 pushbutton controller powers
a system on and off. The system starts after the pushbutton is pressed, which brings the LTM4600’s RUN pin high.
Subsequently, the LTM4600 generates a 5V output which
applies power to each of the four DC/DC converters.
The LTC2930 is configured to mode 13 (see Table 1).
The voltages monitored are 5V, 3.3V, 1.8V, –5.2V, 2.5V
and 12V.
If the KILL input is not driven high within 512ms of a valid
turn-on event, EN pulls low shutting down the system. If
the external 12V supply drops below 9.6V, EN pulls low,
powering down the LTM4600 and subsequent circuitry.
An external 4.7nF capacitor sets the 9.4ms reset timeout
period. Therefore, 9.4ms after the last supply is above
threshold, RST pulls high. The reset timing capacitor
must be chosen to keep the reset timeout period below
512ms. Otherwise, the KILL timer will expire and shut
down the system.
Pressing the pushbutton after the system is powered initiates the power off sequence. An interrupt is set, bringing
EN low immediately and disabling the LTM4600.
2930fa
9
LTC2930
APPLICATIONS INFORMATION
5V
10k
5V
3V
12V
3.3V
1.8V
–5.2V
1V
0.9V
8V
6V
V1
68.1k
1%
86.6k
1%
487k
1%
0.1μF
1020k
1%
V2
V3
RST
V4
1400k
1%
V1
2150k
1%
V2
V3
0.1μF
V6
V6
121k
1%
100k
1%
100k
1%
RESET
LTC2930
V5
V5
R1A
16.2k
1%
RST
V4
LTC2930
MR
VREF
VPG
MR
10k**
GND
100k
1%
CRT
MANUAL RESET
PUSHBUTTON
CRT
47nF
R2A
86.6k
1%
100k
1%
R1B
100k40.2k
1% 1%
VREF
VPG
GND
CRT
CRT
47nF
R2B
59k
1%
tRST = 94ms
2930 F05
**OPTIONAL FOR EXTENDED ESD TOLERANCE
Figure 5. OR-ed System Reset
12V (9.6V THRESHOLD)
LTM4600
VIN
VOUT
RUN
5V
5V
VIN
LT3028
VOUT 3.3V
10k
3.3V
SHDN
EN
VIN
LTC2950-1
VIN
INT
PB
KILL
LT3028
VOUT 1.8V
1.8V
SHDN
SYSTEM
LOGIC
LTC3704
VIN
VOUT –5.2V
–5.2V
RUN/UVLO
VIN
LT3028
VOUT 2.5V
2.5V
SHDN
10k
2930 F06
V1
365k
1%
487k
1%
1500k
1%
V2
RST
V3
SYSTEM RESET
V4
LTC2930
V5
V6
MR
100k
1%
0.1μF
100k
1%
121k
1%
VREF
R1
16.2k
1%
R2
86.6k
1%
VPG
CRT
GND
4.7nF
tRST = 9.4ms
Figure 6. Using a Pushbutton On/Off Controller with the LTC2930
2930fa
10
LTC2930
PACKAGE DESCRIPTION
DD Package
12-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1725 Rev A)
0.70 p0.05
3.50 p0.05
2.10 p0.05
2.38 p0.05
1.65 p0.05
PACKAGE
OUTLINE
0.25 p 0.05
0.45 BSC
2.25 REF
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
3.00 p0.10
(4 SIDES)
R = 0.115
TYP
7
0.40 p 0.10
12
2.38 p0.10
1.65 p 0.10
PIN 1 NOTCH
R = 0.20 OR
0.25 s 45o
CHAMFER
PIN 1
TOP MARK
(SEE NOTE 6)
0.200 REF
0.75 p0.05
6
1
0.23 p 0.05
0.45 BSC
2.25 REF
0.00 – 0.05
(DD12) DFN 0106 REV A
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD AND TIE BARS SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
2930fa
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
11
LTC2930
TYPICAL APPLICATION
Five Supply Monitor, 5% Threshold (3.3V, 1.5V, 1.2V, 1V, 0.9V)
3.3V
1.5V
1.2V
1V
0.9V
68.1k
1%
86.6k
1%
124k
1%
V1
V2
V3
0.1μF
V4
RST
SYSTEM RESET
LTC2930
V5
V6
MR
100k
1%
100k
1%
100k
1%
R1
71.5k
1%
VREF
VPG
GND
CRT
PUSHBUTTON
RESET
CRT
47nF
R2
28k
1%
2930 TA02
tRST = 94ms
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1326
Micropower Triple Supply Monitor for 5V/2.5V, 3.3V and ADJ
4.725V, 3.118V, 1V Threshold (±0.75%) and ADJ
LTC1728
Micropower Triple Supply Monitor with Open-Drain Reset
5-Lead SOT-23 Package
LTC2900
Programmable Quad Supply Monitor
Adjustable Reset, 10-Lead MSOP and DFN Packages
LTC2901
Programmable Quad Supply Monitor
Adjustable Reset and Watchdog Timer
LTC2902
Programmable Quad Supply Monitor
Adjustable Reset and Tolerance (5%, 7.5%, 10%, or 12.5%)
LTC2903
Precision Quad Supply Monitor
6-Lead SOT-23 Package
LTC2904-LTC2907
Three-State Programmable Precision Dual Supply Monitor
8-Lead SOT-23 and DFN Packages
LTC2908
Precision Six Supply Monitor (Four Fixed & Two Adjustable)
8-Lead TSOT-23 and DFN Packages
LTC2909
Precision Triple/Dual Input UV, OV and Negative Voltage Monitor
Shunt Regulated VCC Pin, Adjustable Threshold and Reset,
8-Lead SOT-23 and DFN Packages
LTC2910
Precision Octal Positive/Negative Voltage Supply Monitor
16-Lead SSOP and 5mm × 3mm DFN Packages,
H-Grade Temperature Range
LTC2912-LTC2914
Single/Dual/Quad UV and OV Voltage Monitors
Separate VCC Pin, Adjustable Reset Timer,
H-Grade Temperature Range
LTC2915-LTC2918
Single Supply Monitor with 27 Pin-Selectable Thresholds
Manual Reset, Watchdog, TSOT-8/MSOP-10 and 3mm × 2mm
DFN Packages, H-Grade Temperature Range
LTC2928
Quad Power Supply Sequencer and Supervisor
Easily Configure Power Management without Software,
36-Lead 5mm × 7mm QFN and SSOP Packages
LTC2931
Configurable Six Supply Monitor with Individual Comparator
Outputs
Adjustable Reset and Watchdog Timers, TSSOP-20 Package
LTC2932
Configurable Six Supply Monitor with Individual Comparator
Outputs
Adjustable Reset Timer and Tolerance, TSSOP-20 Package,
Pin-Selectable Tolerance (5%, 7.5%, 10%, or 12.5%),
Reset Disable for Margining
2930fa
12 Linear Technology Corporation
LT 0308 REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2008
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