LINER LTC2935 Ultra-low power supervisor with power-fail output, selectable threshold Datasheet

LTC2935
Ultra-Low Power Supervisor
with Power-Fail Output,
Selectable Thresholds
FEATURES
DESCRIPTION
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The LTC®2935 ultra-low power voltage monitor provides
system initialization, power-fail warning and reset generation functions. Low quiescent current (500nA typical)
makes the LTC2935 an ideal choice for battery-operated
applications.
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500nA Quiescent Current
±1.5% (Max) Accuracy over Temperature
Integrated Precision Attenuators
Eight Pin-Selectable Reset Thresholds
Eight Pin-Selectable Power-Fail Thresholds
Early Warning Power-Fail Output
200ms Reset Timeout
Manual Reset Input
Compact 8-Lead, 2mm × 2mm DFN and
TSOT-23 (ThinSOT™) Packages
APPLICATIONS
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Portable Equipment
Battery-Powered Equipment
Security Systems
Point-of-Sale Devices
Wireless Systems
L, LT, LTC, LTM, Linear Technology and the Linear logo 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.
Three binary threshold-select inputs configure one of
eight integrated reset thresholds, ranging from 1.6V to
3.45V in pre-determined increments. Early warning of an
impending low voltage condition is provided at the powerfail output (PFO), whose threshold is above the configured
reset threshold. Supervisory circuits monitor VCC and
pull RST low when VCC drops below the configured reset
threshold. When VCC is rising from an under-threshold
condition, an internal reset timer is started after exceeding
the reset threshold by 5%. A 200ms reset timeout delays
the return of the RST output to a high state. A pushbutton switch connected to the MR input is typically used to
force a manual reset. Outputs RST and PFO are available
with open-drain (LTC2935-1/LTC2935-3) or active pull-up
(LTC2935-2/LTC2935-4) circuits. Operating temperature
range is from –40°C to 85°C.
TYPICAL APPLICATION
Falling Threshold Selection Table
Configurable Low Power Voltage Monitor
VIN
0.1μF
S1
PFO
S0
BATTERY
POWERED
SYSTEM
LOGIC
LTC2935-2
RST
MR
LTC2935-3/LTC2935-4
RESET
POWER-FAIL
RESET
POWER-FAIL
THRESHOLD THRESHOLD THRESHOLD THRESHOLD
(V)
(V)
(V)
(V)
VCC
S2
LTC2935-1/LTC2935-2
GND
S2
S1
S0
3.30
3.45
2.44
2.56
Low
Low
Low
3.15
3.30
2.32
2.44
Low
Low
High
3.00
3.15
2.20
2.32
Low
High
High
2.85
3.00
2.08
2.20
Low
High
Low
2.70
2.85
1.96
2.08
High
High
Low
2.55
2.70
1.84
1.96
High
Low
Low
2.40
2.55
1.72
1.84
High
Low
High
2.25
2.40
1.60
1.72
High
High
High
2935 TA01a
2935fa
1
LTC2935
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
Input Voltages
VCC........................................................... –0.3V to 6V
S2, S1, S0, MR .........................–0.3V to (VCC + 0.3V)
Output Voltages (PFO, RST)
LTC2935-1/LTC2935-3 ............................. –0.3V to 6V
LTC2935-2/LTC2935-4 ..............–0.3V to (VCC + 0.3V)
RMS Currents
PFO, RST ..........................................................±5mA
Operating Ambient Temperature Range
LTC2935C ................................................ 0°C to 70°C
LTC2935I.............................................. –40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
TSOT-23 Package.............................................. 300°C
PIN CONFIGURATION
TOP VIEW
MR 2
RST 3
PFO 4
TOP VIEW
8 S2
VCC 1
9
S2 1
S1 2
S0 3
GND 4
7 S1
6 S0
5 GND
DC PACKAGE
8-LEAD (2mm s 2mm) PLASTIC DFN
TJMAX = 125°C, θJA = 102°C/W
EXPOSED PAD (PIN 9), PCB GND CONNECTION OPTIONAL
8 VCC
7 MR
6 RST
5 PFO
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
TJMAX = 125°C, θJA = 195°C/W
ORDER INFORMATION
Lead Free Finish
TAPE AND REEL (MINI)
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC2935CTS8-1#TRMPBF
LTC2935CTS8-1#TRPBF
LTDPW
8-Lead Plastic TSOT-23
0°C to 70°C
LTC2935ITS8-1#TRMPBF
LTC2935ITS8-1#TRPBF
LTDPW
8-Lead Plastic TSOT-23
–40°C to 85°C
LTC2935CTS8-2#TRMPBF
LTC2935CTS8-2#TRPBF
LTDQB
8-Lead Plastic TSOT-23
0°C to 70°C
LTC2935ITS8-2#TRMPBF
LTC2935ITS8-2#TRPBF
LTDQB
8-Lead Plastic TSOT-23
–40°C to 85°C
LTC2935CTS8-3#TRMPBF
LTC2935CTS8-3#TRPBF
LTFHV
8-Lead Plastic TSOT-23
0°C to 70°C
LTC2935ITS8-3#TRMPBF
LTC2935ITS8-3#TRPBF
LTFHV
8-Lead Plastic TSOT-23
–40°C to 85°C
LTC2935CTS8-4#TRMPBF
LTC2935CTS8-4#TRPBF
LTFHX
8-Lead Plastic TSOT-23
0°C to 70°C
LTC2935ITS8-4#TRMPBF
LTC2935ITS8-4#TRPBF
LTFHX
8-Lead Plastic TSOT-23
–40°C to 85°C
LTC2935CDC-1#TRMPBF
LTC2935CDC-1#TRPBF
LDPX
8-Lead (2mm × 2mm) Plastic DFN
0°C to 70°C
LTC2935IDC-1#TRMPBF
LTC2935IDC-1#TRPBF
LDPX
8-Lead (2mm × 2mm) Plastic DFN
–40°C to 85°C
LTC2935CDC-2#TRMPBF
LTC2935CDC-2#TRPBF
LDQC
8-Lead (2mm × 2mm) Plastic DFN
0°C to 70°C
LTC2935IDC-2#TRMPBF
LTC2935IDC-2#TRPBF
LDQC
8-Lead (2mm × 2mm) Plastic DFN
–40°C to 85°C
LTC2935CDC-3#TRMPBF
LTC2935CDC-3#TRPBF
LFHW
8-Lead (2mm × 2mm) Plastic DFN
0°C to 70°C
LTC2935IDC-3#TRMPBF
LTC2935IDC-3#TRPBF
LFHW
8-Lead (2mm × 2mm) Plastic DFN
–40°C to 85°C
LFHY
8-Lead (2mm × 2mm) Plastic DFN
LTC2935CDC-4#TRMPBF
LTC2935CDC-4#TRPBF
8-Lead (2mm × 2mm) Plastic DFN
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on lead based finish parts.
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/
LTC2935IDC-4#TRMPBF
LTC2935IDC-4#TRPBF
LFHY
0°C to 70°C
–40°C to 85°C
2935fa
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LTC2935
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C, VCC = 3.6V, unless otherwise noted. (Note 2)
SYMBOL
PARAMETER
VCC
VCC Input Supply Voltage
CONDITIONS
l
MIN
ICC
VCC Input Supply Current
l
225
S2 = Low : S1 = Low : S0 = Low
l
TYP
MAX
UNITS
5.5
V
500
1000
nA
3.251
3.300
3.349
V
Reset Thresholds (LTC2935-1/LTC2935-2)
VRTF1
Reset Threshold 1 (VCC Falling)
VRTF2
Reset Threshold 2 (VCC Falling)
S2 = Low : S1 = Low : S0 = High
l
3.103
3.150
3.197
V
VRTF3
Reset Threshold 3 (VCC Falling)
S2 = Low : S1 = High : S0 = High
l
2.955
3.000
3.045
V
VRTF4
Reset Threshold 4 (VCC Falling)
S2 = Low : S1 = High : S0 = Low
l
2.808
2.850
2.892
V
VRTF5
Reset Threshold 5 (VCC Falling)
S2 = High : S1 = High : S0 = Low
l
2.660
2.700
2.740
V
VRTF6
Reset Threshold 6 (VCC Falling)
S2 = High : S1 = Low : S0 = Low
l
2.512
2.550
2.588
V
VRTF7
Reset Threshold 7 (VCC Falling)
S2 = High : S1 = Low : S0 = High
l
2.364
2.400
2.436
V
VRTF8
Reset Threshold 8 (VCC Falling)
S2 = High : S1 = High : S0 = High
l
2.217
2.250
2.283
ΔVRTF
Reset Threshold Differential VRTF(N+1) – VRTF(N)
(Note 3)
l
142
150
158
mV
VRT(HYST)
Reset Threshold Hysteresis (VCC Rising)
Relative to Any Selected Reset Threshold
l
4.5
5
6
%
tUVR
Undervoltage Detect to RST Falling
VCC Below Threshold by 1% (Note 3)
1
V
ms
Reset Thresholds (LTC2935-3/LTC2935-4)
VRTF1
Reset Threshold 1 (VCC Falling)
S2 = Low : S1 = Low : S0 = Low
l
2.404
2.440
2.476
V
VRTF2
Reset Threshold 2 (VCC Falling)
S2 = Low : S1 = Low : S0 = High
l
2.286
2.320
2.354
V
VRTF3
Reset Threshold 3 (VCC Falling)
S2 = Low : S1 = High : S0 = High
l
2.167
2.200
2.233
V
VRTF4
Reset Threshold 4 (VCC Falling)
S2 = Low : S1 = High : S0 = Low
l
2.049
2.080
2.111
V
VRTF5
Reset Threshold 5 (VCC Falling)
S2 = High : S1 = High : S0 = Low
l
1.931
1.960
1.989
V
VRTF6
Reset Threshold 6 (VCC Falling)
S2 = High : S1 = Low : S0 = Low
l
1.813
1.840
1.867
V
VRTF7
Reset Threshold 7 (VCC Falling)
S2 = High : S1 = Low : S0 = High
l
1.695
1.720
1.745
V
VRTF8
Reset Threshold 8 (VCC Falling)
S2 = High : S1 = High : S0 = High
l
1.576
1.600
1.624
ΔVRTF
Reset Threshold Differential VRTF(N+1) – VRTF(N)
(Note 3)
l
112
120
128
mV
VRT(HYST)
Reset Threshold Hysteresis (VCC Rising)
Relative to Any Selected Reset Threshold
l
4.5
5
6
%
tUVR
Undervoltage Detect to RST Falling
VCC Below Threshold by 1% (Note 3)
1
V
ms
Power-Fail Thresholds (LTC2935-1/LTC2935-2)
ΔVPFT
Power-Fail Threshold Differential VPFT(N) – VRTF(N)
VPFT(HYST) Power-Fail Threshold Hysteresis
tUVP
Undervoltage Detect to PFO Falling
Any Selected Reset Threshold (VCC Falling)
l
100
150
200
mV
Relative to Any Selected Power-Fail Threshold
(VCC Rising)
l
2
2.5
3.5
%
VCC Below Threshold by 1% (Note 3)
1
ms
Power-Fail Thresholds (LTC2935-3/LTC2935-4)
ΔVPFT
Power-Fail Threshold Differential VPFT(N) – VRTF(N)
VPFT(HYST) Power-Fail Threshold Hysteresis
tUVP
Undervoltage Detect to PFO Falling
Any Selected Reset Threshold (VCC Falling)
l
70
120
170
mV
Relative to Any Selected Power-Fail Threshold
(VCC Rising)
l
2
2.5
3
%
VCC Below Threshold by 1% (Note 3)
1
ms
Control Inputs: MR, S2, S1, S0
VIN(TH)
Control Input Threshold
S2, S1, S0
MR
l 0.3 • VCC
l
0.4
tPW
Input Pulse Width
MR
l
20
tPD
Propagation Delay to RST Falling
Manual Reset Falling
l
2
5
20
μs
RPU
Internal Pull-Up Resistance
MR
l
600
900
1200
kΩ
ILK
Input Leakage Current
S2, S1, S0 = VCC or GND
l
±1
±10
nA
0.7 • VCC
1.4
V
V
μs
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LTC2935
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C, VCC = 3.6V, unless otherwise noted. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
25
50
100
150
mV
mV
±1
±10
nA
200
260
ms
Reset and Power-Fail Outputs: RST, PFO
VOL
Voltage Output Low
VCC = 1V, 200μA Pull-Up Current
VCC = 3V, 3mA Pull-Up Current
S2, S1, S0 = Low
l
l
VOH
Voltage Output High (LTC2935-2)
–200μA Pull-Down Current
l 0.7 • VCC
IOH
Current Output High, Leakage (LTC2935-1)
VRST, VPFO = 3.6V
l
tRST
Reset Timeout Period
l
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. Guaranteed by design. Characterized, but not production tested.
TYPICAL PERFORMANCE CHARACTERISTICS
800
85°C
600
25°C
400
–40°C
200
0
1
2
3
VCC (V)
4
5
6
1.015
3.0
1.010
2.5
1.005
1.000
0.995
0.990
0.985
–50
–25
0
25
50
TEMPERATURE (°C)
75
2935 G01
COMPARATORS PULL DOWN
ABOVE CURVE
1.5
1.0
0
0.1
100
1
10
COMPARATOR OVERDRIVE (%)
100
2935 G03
Voltage Output Low vs Pull-Up
Current (RST, PFO)
Voltage Output High vs Pull-Down
Current (RST, PFO)
3.6
100
VCC = 3.6V
240
VCC = 3V
LTC2935-2
VCC = 3.6V
85°C
80
3.5
25°C
VOL (mV)
220
tRST (ms)
2.0
2935 G02
Reset Timeout Period
vs Temperature
260
VCC = 3.6V
0.5
200
60
VOH (mV)
0
Comparator Undervoltage
Glitch Immunity
GLITCH DURATION, t UV (ms)
S0 = S1 = S2 = GND
NORMALIZED THRESHOLD (V/ V)
ICC (nA)
1000
TA = 25°C, unless otherwise noted.
Normalized Reset and Power-Fail
Thresholds vs Temperature
Supply Current vs Supply Voltage
140
V
–40°C
40
–40°C
3.4
25°C
180
3.3
20
160
140
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
2935 G04
0
85°C
3.2
0
1
2
3
4
PULL-UP CURRENT (mA)
5
2935 G05
0
–0.4
–0.6
–0.8
–0.2
PULL-DOWN CURRENT (mA)
–1
2935 G06
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LTC2935
TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs S0, S1, S2
Input Voltage
Supply Current vs MR Input Voltage
5
VCC = 3.6V
200
4
150
3
ICC (μA)
ICC (μA)
250
TA = 25°C, unless otherwise noted.
100
50
VCC = 3.6V
2
1
0
0
0
0.5
1
1.5
2
2.5
3
S0, S1, S2 INPUT VOLTAGE (V)
3.5
4
2935 G07
0
0.5
1
1.5
2
2.5
3
MR INPUT VOLTAGE (V)
3.5
4
2935 G08
PIN FUNCTIONS
Exposed Pad (DFN Only): Exposed Pad may be left floating
or connected to device ground.
GND: Device ground.
MR: Manual Reset Input. Attach a pushbutton switch
between this input and ground. A logic low on this input
pulls RST low. When the MR input returns to logic high,
RST returns high after 200ms. Tie to VCC if unused.
PFO: Power-Fail Output. PFO pulls low when VCC falls
below the power-fail threshold. The power-fail threshold is above the configured falling reset threshold by a
pre-determined margin. PFO is released when VCC rises
above the power-fail threshold by 2.5%. PFO is available
with open-drain (LTC2935-1/LTC2935-3) or active pull-up
(LTC2935-2/LTC2935-4) outputs. Leave open if unused.
RST: Reset Output. RST pulls low when VCC falls below the
reset threshold. RST is released 200ms after VCC exceeds
the reset threshold plus 5% hysteresis. RST is available
with open-drain (LTC2935-1/LTC2935-3) or active pull-up
(LTC2935-2/LTC2935-4) outputs. Leave open if unused.
S2, S1, S0: Threshold Selection Inputs. Tie to GND or
VCC for required reset threshold. See the Falling Threshold
Selection Table on page 1 for settings.
VCC: Power Supply and Monitored Voltage Input. Bypass
VCC with a 0.1μF capacitor to GND.
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LTC2935
BLOCK DIAGRAM
LTC2935-2/LTC2935-4
MR
VCC
900k
VCC
–
RST
RC
RESET
DELAY
+
S0
LTC2935-2/LTC2935-4
S1
VCC
S2
0.4V
+
PFO
PC
–
GND
2935 BD
TIMING DIAGRAM
VPFT
VRTF
VCC
PFO
t RST
t RST
RST
MR
2935 TD
t PD
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LTC2935
APPLICATIONS INFORMATION
VOLTAGE MONITORING
Unmanaged power can cause various system problems.
At power-up, voltage fluctuation around critical thresholds
can cause improper system or processor initialization.
The LTC2935 provides power management capabilities
for the system power-up phase. The supervisory device
issues a system reset after the monitored voltage has
stabilized. Built-in hysteresis and filtering ensures that
fluctuations due to load transients or supply noise do
not cause chattering of the status outputs. Comparator
undervoltage glitch immunity is shown in the Typical
Performance Characteristics section. The curve demonstrates the transient amplitude and width required to
switch the comparators.
Because many batteries exhibit large series resistance,
load currents can cause significant voltage drops. The
low DC current draw of the LTC2935 (at any input voltage) does not add to the loading problem. When voltage
is initially applied to VCC, RST and PFO pull low once there
is enough voltage to turn on the pull-down devices (1V
maximum).
If the monitored supply voltage falls to the power-fail
threshold, the built-in power-fail comparator pulls PFO
low. At this point, there remains a voltage margin before
the RST output pulls low. PFO remains low until VCC rises
above the power-fail threshold plus 2.5% hysteresis. PFO
is typically used in signal preparation for controlled shutdown. For example, the PFO output may be connected to
a processor nonmaskable interrupt. Upon interrupt, the
processor may begin shutdown procedures. Shutdown
events may include supply sequencing and/or storage/
erasure of system state in nonvolatile memory.
If the monitored voltage drops below the reset threshold,
RST pulls low until VCC rises above the reset threshold plus
5% hysteresis. This may occur through battery charging
or replacement. An internal reset timer delays the return
of the RST output to a high state to provide settling and
initialization time. The RST output is typically connected
to a processor reset input.
Few, if any external components are necessary for reliable
operation. However, a decoupling capacitor between VCC
and ground is recommended (0.01μF minimum).
Threshold Configuration
The LTC2935 monitors and compares the VCC voltage
against two internal thresholds during operation. The
higher threshold (power-fail) is the level used for early
warning of a low voltage condition, reported on the PFO
output. The lower threshold (reset) is the level at which the
RST output pulls low. Use system requirements to choose
the appropriate reset threshold from Table 1.
Table 1. Falling Threshold Selection
LTC2935-1/LTC2935-2
LTC2935-3/LTC2935-4
RESET
POWER-FAIL
RESET
POWER-FAIL
THRESHOLD THRESHOLD THRESHOLD THRESHOLD
(V)
(V)
(V)
(V)
S2
S1
S0
3.30
3.45
2.44
2.56
Low Low Low
3.15
3.30
2.32
2.44
Low Low High
3.00
3.15
2.20
2.32
Low High High
2.85
3.00
2.08
2.20
Low High Low
2.70
2.85
1.96
2.08
High High Low
2.55
2.70
1.84
1.96
High Low Low
2.40
2.55
1.72
1.84
High Low High
2.25
2.40
1.60
1.72
High High High
In the LTC2935-1/LTC2935-2 the power-fail threshold
is always 150mV higher than the configured reset
threshold. In the LTC2935-3/LTC2935-4 the power-fail
threshold is always 120mV higher than the configured
reset threshold. Set the threshold selection inputs (S2,
S1, S0) accordingly.
2935fa
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LTC2935
APPLICATIONS INFORMATION
Selecting Output Logic Style
The LTC2935 status outputs are available in two options: open-drain (LTC2935-1/LTC2935-3) or active
pull-up (LTC2935-2/LTC2935-4). The open-drain options
(LTC2935-1/LTC2935-3) allow the outputs to be pulled up
to a user defined voltage with a resistor. The open-drain
pull-up voltage may be greater than VCC (5.5V maximum),
which is not always possible with inferior battery supervisors, due to internal clamps. When the status outputs are
low, power is dissipated in the pull-up resistors. Recommended resistor values lie in the range between 10k and
470k. Figure 1 demonstrates typical LTC2935-1/LTC2935-3
RST output behavior.
undetermined voltages when connected to high impedance
(such as CMOS logic inputs). The resistor value should
be small enough to provide effective pull-down without
excessively loading the pull-up circuitry. A 100k resistor
from output to ground is satisfactory for most applications.
When the status outputs are high, power is dissipated in
the pull-down resistors. Figure 2 demonstrates typical
LTC2935-2/LTC2935-4 RST output behavior.
Manual Reset Input
The active pull-up options (LTC2935-2/LTC2935-4) eliminate the need for external pull-up resistors on the status
outputs. Integrated pull-up devices pull the outputs up to
VCC. Actively pulled up outputs may not be driven above
VCC.
When VCC is above its reset threshold, and the manual
reset input (MR) is pulled low, the RST output is forced low.
RST remains low for 200ms after the manual reset input is
released and pulled high. The manual reset input is pulled
up internally through 900k to VCC. If external leakage currents have the ability to pull down the manual reset input
below its logic threshold, a lower value pull-up resistor,
placed between VCC and MR will fix the problem.
Some applications require the RST and/or PFO outputs to
be valid with VCC down to ground. Active pull-up handles
this requirement with the addition of an external resistor
from the output to ground. The resistor provides a path
for leakage currents, preventing the output from floating to
Input MR is often pulled down through a pushbutton
switch requiring human contact. If extended ESD tolerance is required, series resistance between the switch and
the input is recommended. For most applications, a 10k
resistor provides sufficient current limiting.
3.5
LTC2935-1
S2 = GND
3.0 S1 = S0 = V
CC
LTC2935-2
S2 = GND
3.0 S1 = S0 = V
CC
2.5
2.5
RST (V)
RST (V)
3.5
2.0
1.5
2.0
1.5
1.0
1.0
0.5
0.5
0
0
0.5
1
1.5
2
VCC (V)
2.5
3
3.5
2935 F01
Figure 1. RST vs VCC with 10k Pull-Up
0
0
0.5
1
1.5
2
2.5
VCC (V)
3
3.5
2935 F02
Figure 2. RST vs VCC
2935fa
8
LTC2935
TYPICAL APPLICATIONS
Battery Monitor with Interface to Low Voltage Logic
3μA LDO
IN
SHDN
LT3009
OUT
GND
ADJ
1.8V
1.18M
1μF
590k
100k
100k
VCC
+
Li-Ion
0.1μF
S1
S2
RESD*
10k
VDD
PFO
S0
NMI
LTC2935-1
μP
RST
MR
RST
GND
MANUAL
PB1
RESET
PUSHBUTTON
POWER FAIL FALLING THRESHOLD = 3.15V
RESET FALLING THRESHOLD = 3.00V
2935 TA02
*OPTIONAL RESISTOR FOR ADDED ESD PROTECTION
Alkaline Cell Stack Voltage Monitor
VCC
+
1.5V
0.1μF
S0
S2
+
+
S1
MR
PFO
LOW BATTERY
RST
SYSTEM RESET
LTC2935-2
1.5V
GND
1.5V
2935 TA03
POWER FAIL FAIL THRESHOLD = 2.55V
RESET THRESHOLD = 2.40V
Coin Cell Voltage Monitor
VCC
+
CR2032
0.1μF
S2
S1
MR
PFO
LOW BATTERY
RST
SYSTEM RESET
LTC2935-2
S0
GND
2935 TA04
POWER FAIL FAIL THRESHOLD = 2.70V
RESET THRESHOLD = 2.55V
2935fa
9
LTC2935
PACKAGE DESCRIPTION
DC Package
8-Lead Plastic DFN (2mm × 2mm)
(Reference LTC DWG # 05-08-1719 Rev Ø)
0.70 ±0.05
2.55 ±0.05
1.15 ±0.05 0.64 ±0.05
(2 SIDES)
PACKAGE
OUTLINE
0.25 ± 0.05
0.45 BSC
1.37 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
R = 0.05
TYP
2.00 ±0.10
(4 SIDES)
PIN 1 BAR
TOP MARK
(SEE NOTE 6)
R = 0.115
TYP
5
8
0.40 ± 0.10
0.64 ± 0.10
(2 SIDES)
PIN 1 NOTCH
R = 0.20 OR
0.25 × 45°
CHAMFER
(DC8) DFN 0106 REVØ
4
0.200 REF
1
0.23 ± 0.05
0.45 BSC
0.75 ±0.05
1.37 ±0.10
(2 SIDES)
0.00 – 0.05
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 SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
2935fa
10
LTC2935
PACKAGE DESCRIPTION
TS8 Package
8-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1637)
0.52
MAX
2.90 BSC
(NOTE 4)
0.65
REF
1.22 REF
1.4 MIN
3.85 MAX 2.62 REF
2.80 BSC
1.50 – 1.75
(NOTE 4)
PIN ONE ID
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.22 – 0.36
8 PLCS (NOTE 3)
0.65 BSC
0.80 – 0.90
0.20 BSC
0.01 – 0.10
1.00 MAX
DATUM ‘A’
0.30 – 0.50 REF
0.09 – 0.20
(NOTE 3)
1.95 BSC
TS8 TSOT-23 0802
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
2935fa
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
LTC2935
TYPICAL APPLICATION
Portable Device Battery Monitor
3μA LDO
1.8V
IN
+
VCC
Li-Ion
0.1μF
MR
100k
LT3009
OUT
GND
ADJ
SHDN
1.18M
S0
S1
S2
LTC2935-1
GND
1μF
RST
590k
100k
LOW BATTERY
EARLY WARNING
PFO
POWER FAIL FALLING THRESHOLD = 3.15V
RESET FALLING THRESHOLD = 3.00V
2935 TA05
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC690
5V Supply Monitor, Watchdog Timer and Battery Backup
4.65V Threshold
LTC694-3.3
3.3V Supply Monitor, Watchdog Timer and Battery Backup
2.9V Threshold
LTC1232
5V Supply Monitor, Watchdog Timer and Pushbutton Reset
4.37V/4.62V Threshold
LTC1326
Micropower Triple Supply Monitor for 5V/2.5V, 3.3V and ADJ
4.725V, 3.118V, 1V Threshold (±0.75%) and ADJ
LTC1726
Micropower Triple Supply Monitor for 2.5V/5V, 3.3V and ADJ
Adjustable Reset and Watchdog Timeouts
LTC1727
Micropower Triple Supply Monitor with Open-Drain Reset
Individual Monitor Outputs in MSOP
LTC1728
Micropower Triple Supply Monitor with Open-Drain Reset
5-Lead SOT-23 Package
LTC1985
Micropower Triple Supply Monitor with Push-Pull Reset Output
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
LTC2903
Precision Quad Supply Monitor
6-Lead SOT-23 Package
LTC2904/LTC2905/
LTC2906/LTC2907
Three-State Programmable Precision Dual Supply Monitor
8-Lead SOT-23 and DFN Packages
LTC2908
Precision Six-Supply Monitor (Four Fixed and 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
Octal Positive/Negative Voltage Monitor
Separate VCC Pin, Eight Inputs, Up to Two Negative Monitors
Adjustable Reset Timer, 16-Lead SSOP and DFN Packages
LTC2912/LTC2913/
LTC2914
Single/Dual/Quad UV and OV Voltage Monitors
Separate VCC Pin, Adjustable Reset Timer
LTC2915/LTC2916/
LTC2917/LTC2918
Single Voltage Supervisors with 27 Pin-Selectable Thresholds
Manual Reset and Watchdog Functions
LTC2934
Ultralow Power Supervisor with Power-Fail Output
500nA Quiescent Current, 2mm × 2mm 8-Lead DFN and
TSOT-23 Packages, Adjustable via External Resistors
2935fa
12 Linear Technology Corporation
LT 0609 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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