LTC2935IDC-4#PBF [Linear]
LTC2935 - Ultra-Low Power Supervisor with Power-Fail Output, Selectable Thresholds; Package: DFN; Pins: 8; Temperature Range: -40°C to 85°C;
| 型号： | LTC2935IDC-4#PBF |
| 厂家： | 
Linear |
| 描述： | LTC2935 - Ultra-Low Power Supervisor with Power-Fail Output, Selectable Thresholds; Package: DFN; Pins: 8; Temperature Range: -40°C to 85°C 光电二极管 |
| 文件： | 总12页 (文件大小：129K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC2935
Ultra-Low Power Supervisor
with Power-Fail Output,
Selectable Thresholds
FEATURES
DESCRIPTION
The LTC®2935 ultra-low power voltage monitor provides
system initialization, power-fail warning and reset gen-
eration functions. Low quiescent current (500nA typical)
makes the LTC2935 an ideal choice for battery-operated
applications.
n
500nA Quiescent Current
n
±±15ꢀ ꢁMaꢂx Accuracꢃ oꢄer ꢅemperature
n
Integrated Precision Attenuators
n
Eight Pin-Selectable Reset ꢅhresholds
n
Eight Pin-Selectable Power-Fail ꢅhresholds
n
Early Warning Power-Fail Output
200ms Reset Timeout
Manual Reset Input
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 power-
failoutput(PFO), whosethresholdisabovetheconfigured
n
n
n
Compact 8-Lead, 2mm × 2mm DFN and
TSOT-23 (ThinSOT™) Packages
reset threshold. Supervisory circuits monitor V and
CC
pull RST low when V drops below the configured reset
APPLICATIONS
CC
threshold. When V is rising from an under-threshold
CC
n
Portable Equipment
condition, aninternalresettimerisstartedafterexceeding
the reset threshold by 5%. A 200ms reset timeout delays
the return of the RST output to a high state. A pushbut-
ton 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.
n
Battery-Powered Equipment
n
Security Systems
n
Point-of-Sale Devices
n
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.
TYPICAL APPLICATION
Falling ꢅhreshold Selection ꢅable
Configurable Low Power Voltage Monitor
LꢅC2935-±/LꢅC2935-2
RESEꢅ POWER-FAIL
LꢅC2935-3/LꢅC2935-4
RESEꢅ POWER-FAIL
V
IN
ꢅHRESHOLD ꢅHRESHOLD ꢅHRESHOLD ꢅHRESHOLD
V
CC
ꢁVx
ꢁVx
ꢁVx
ꢁVx
S2
S±
S0
S2
S1
S0
PFO
RST
0.1μF
3.30
3.15
3.00
2.85
2.70
2.55
2.40
2.25
3.45
3.30
3.15
3.00
2.85
2.70
2.55
2.40
2.44
2.32
2.20
2.08
1.96
1.84
1.72
1.60
2.56
2.44
2.32
2.20
2.08
1.96
1.84
1.72
Low Low Low
Low Low High
Low High High
Low High Low
High High Low
High Low Low
High Low High
High High High
BATTERY
POWERED
SYSTEM
LOGIC
LTC2935-2
GND
MR
2935 TA01a
2935fa
1
LTC2935
ABSOLUTE MAXIMUM RATINGS
ꢁNotes ±, 2x
Operating Ambient Temperature Range
Input Voltages
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)
V ........................................................... –0.3V to 6V
CC
S2, S1, S0, MR.........................–0.3V to (V + 0.3V)
CC
Output Voltages (PFO, RST)
LTC2935-1/LTC2935-3............................. –0.3V to 6V
TSOT-23 Package.............................................. 300°C
LTC2935-2/LTC2935-4..............–0.3V to (V + 0.3V)
CC
RMS Currents
PFO, RST .......................................................... 5mA
PIN CONFIGURATION
TOP VIEW
TOP VIEW
1
2
3
4
8
7
6
5
S2
V
CC
S2 1
S1 2
S0 3
8 V
CC
MR
RST
PFO
S1
9
7 MR
6 RST
5 PFO
S0
GND
GND 4
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
= 125°C, θ = 195°C/W
DC PACKAGE
8-LEAD (2mm s 2mm) PLASTIC DFN
T
JMAX
JA
T
= 125°C, θ = 102°C/W
JA
EXPOSED PAD (PIN 9), PCB GND CONNECTION OPTIONAL
JMAX
ORDER INFORMATION
Lead Free Finish
ꢅAPE AND REEL ꢁMINIx
LTC2935CTS8-1#TRMPBF
LTC2935ITS8-1#TRMPBF
LTC2935CTS8-2#TRMPBF
LTC2935ITS8-2#TRMPBF
LTC2935CTS8-3#TRMPBF
LTC2935ITS8-3#TRMPBF
LTC2935CTS8-4#TRMPBF
LTC2935ITS8-4#TRMPBF
LTC2935CDC-1#TRMPBF
LTC2935IDC-1#TRMPBF
LTC2935CDC-2#TRMPBF
LTC2935IDC-2#TRMPBF
LTC2935CDC-3#TRMPBF
LTC2935IDC-3#TRMPBF
LTC2935CDC-4#TRMPBF
LTC2935IDC-4#TRMPBF
ꢅAPE AND REEL
PARꢅ MARKING*
LTDPW
LTDPW
LTDQB
LTDQB
LTFHV
LTFHV
LTFHX
LTFHX
LDPX
PACKAGE DESCRIPꢅION
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
8-Lead Plastic TSOT-23
ꢅEMPERAꢅURE RANGE
0°C to 70°C
LTC2935CTS8-1#TRPBF
LTC2935ITS8-1#TRPBF
LTC2935CTS8-2#TRPBF
LTC2935ITS8-2#TRPBF
LTC2935CTS8-3#TRPBF
LTC2935ITS8-3#TRPBF
LTC2935CTS8-4#TRPBF
LTC2935ITS8-4#TRPBF
LTC2935CDC-1#TRPBF
LTC2935IDC-1#TRPBF
LTC2935CDC-2#TRPBF
LTC2935IDC-2#TRPBF
LTC2935CDC-3#TRPBF
LTC2935IDC-3#TRPBF
LTC2935CDC-4#TRPBF
LTC2935IDC-4#TRPBF
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
8-Lead (2mm × 2mm) Plastic DFN
8-Lead (2mm × 2mm) Plastic DFN
8-Lead (2mm × 2mm) Plastic DFN
8-Lead (2mm × 2mm) Plastic DFN
8-Lead (2mm × 2mm) Plastic DFN
8-Lead (2mm × 2mm) Plastic DFN
8-Lead (2mm × 2mm) Plastic DFN
8-Lead (2mm × 2mm) Plastic DFN
LDPX
–40°C to 85°C
0°C to 70°C
LDQC
LDQC
–40°C to 85°C
0°C to 70°C
LFHW
LFHW
–40°C to 85°C
0°C to 70°C
LFHY
LFHY
–40°C to 85°C
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/
2935fa
2
LTC2935
ELECTRICAL CHARACTERISTICS ꢅhe l denotes the specifications which applꢃ oꢄer the full operating
temperature range, otherwise specifications are at ꢅA = 25°C, VCC = 316V, unless otherwise noted1 ꢁNote 2x
SYMBOL PARAMEꢅER
CONDIꢅIONS
MIN
ꢅYP
MAX UNIꢅS
l
l
V
V
V
Input Supply Voltage
Input Supply Current
5.5
V
CC
CC
CC
I
CC
225
500
1000
nA
Reset ꢅhresholds ꢁLꢅC2935-±/LꢅC2935-2x
l
l
l
l
l
l
l
l
l
l
V
V
V
V
V
V
V
V
Reset Threshold 1 (V Falling)
S2 = Low : S1 = Low : S0 = Low
S2 = Low : S1 = Low : S0 = High
S2 = Low : S1 = High : S0 = High
S2 = Low : S1 = High : S0 = Low
S2 = High : S1 = High : S0 = Low
S2 = High : S1 = Low : S0 = Low
S2 = High : S1 = Low : S0 = High
S2 = High : S1 = High : S0 = High
(Note 3)
3.251
3.103
2.955
2.808
2.660
2.512
2.364
2.217
142
3.300
3.150
3.000
2.850
2.700
2.550
2.400
2.250
150
3.349
3.197
3.045
2.892
2.740
2.588
2.436
2.283
158
V
V
RTF1
RTF2
RTF3
RTF4
RTF5
RTF6
RTF7
RTF8
CC
Reset Threshold 2 (V Falling)
CC
Reset Threshold 3 (V Falling)
V
CC
Reset Threshold 4 (V Falling)
V
CC
Reset Threshold 5 (V Falling)
V
CC
Reset Threshold 6 (V Falling)
V
CC
Reset Threshold 7 (V Falling)
V
CC
Reset Threshold 8 (V Falling)
V
CC
Reset Threshold Differential V
– V
mV
%
ms
ΔV
RTF(N+1)
RTF(N)
RTF
RT(HYST)
UVR
V
Reset Threshold Hysteresis (V Rising)
Relative to Any Selected Reset Threshold
4.5
5
6
CC
t
Undervoltage Detect to RST Falling
V
Below Threshold by 1% (Note 3)
1
CC
Reset ꢅhresholds ꢁLꢅC2935-3/LꢅC2935-4x
l
l
l
l
l
l
l
l
l
l
V
V
V
V
V
V
V
V
Reset Threshold 1 (V Falling)
S2 = Low : S1 = Low : S0 = Low
S2 = Low : S1 = Low : S0 = High
S2 = Low : S1 = High : S0 = High
S2 = Low : S1 = High : S0 = Low
S2 = High : S1 = High : S0 = Low
S2 = High : S1 = Low : S0 = Low
S2 = High : S1 = Low : S0 = High
S2 = High : S1 = High : S0 = High
(Note 3)
2.404
2.286
2.167
2.049
1.931
1.813
1.695
1.576
112
2.440
2.320
2.200
2.080
1.960
1.840
1.720
1.600
120
2.476
2.354
2.233
2.111
1.989
1.867
1.745
1.624
128
V
V
RTF1
RTF2
RTF3
RTF4
RTF5
RTF6
RTF7
RTF8
CC
Reset Threshold 2 (V Falling)
CC
Reset Threshold 3 (V Falling)
V
CC
Reset Threshold 4 (V Falling)
V
CC
Reset Threshold 5 (V Falling)
V
CC
Reset Threshold 6 (V Falling)
V
CC
Reset Threshold 7 (V Falling)
V
CC
Reset Threshold 8 (V Falling)
V
CC
Reset Threshold Differential V
– V
mV
%
ms
ΔV
RTF(N+1)
RTF(N)
RTF
RT(HYST)
UVR
V
Reset Threshold Hysteresis (V Rising)
Relative to Any Selected Reset Threshold
4.5
5
6
CC
t
Undervoltage Detect to RST Falling
V
Below Threshold by 1% (Note 3)
1
CC
Power-Fail ꢅhresholds ꢁLꢅC2935-±/LꢅC2935-2x
l
l
Power-Fail Threshold Differential V
Power-Fail Threshold Hysteresis
– V
Any Selected Reset Threshold (V Falling)
100
2
150
2.5
200
3.5
mV
%
ΔV
PFT(N)
RTF(N)
CC
PFT
V
Relative to Any Selected Power-Fail Threshold
(V Rising)
CC
PFT(HYST)
t
Undervoltage Detect to PFO Falling
V
Below Threshold by 1% (Note 3)
CC
1
ms
UVP
Power-Fail ꢅhresholds ꢁLꢅC2935-3/LꢅC2935-4x
l
l
Power-Fail Threshold Differential V
Power-Fail Threshold Hysteresis
– V
Any Selected Reset Threshold (V Falling)
70
2
120
2.5
170
3
mV
%
ΔV
PFT(N)
RTF(N)
CC
PFT
V
Relative to Any Selected Power-Fail Threshold
(V Rising)
CC
PFT(HYST)
t
Undervoltage Detect to PFO Falling
V
Below Threshold by 1% (Note 3)
CC
1
ms
UVP
Control Inputs: MR, S2, S±, S0
l
l
V
Control Input Threshold
S2, S1, S0
MR
0.3 • V
0.4
0.7 • V
1.4
V
V
IN(TH)
CC
CC
l
l
l
l
t
t
Input Pulse Width
MR
20
2
μs
μs
PW
PD
Propagation Delay to RST Falling
Internal Pull-Up Resistance
Input Leakage Current
Manual Reset Falling
5
900
1
20
R
MR
600
1200
10
kΩ
PU
I
S2, S1, S0 = V or GND
nA
LK
CC
2935fa
3
LTC2935
ELECTRICAL CHARACTERISTICS ꢅhe l denotes the specifications which applꢃ oꢄer the full operating
temperature range, otherwise specifications are at ꢅA = 25°C, VCC = 316V, unless otherwise noted1 ꢁNote 2x
SYMBOL PARAMEꢅER
CONDIꢅIONS
MIN
ꢅYP
MAX UNIꢅS
Reset and Power-Fail Outputs: RST, PFO
l
l
V
Voltage Output Low
V
V
= 1V, 200μA Pull-Up Current
= 3V, 3mA Pull-Up Current
25
50
100
150
mV
mV
OL
CC
CC
S2, S1, S0 = Low
l
l
l
V
Voltage Output High (LTC2935-2)
Current Output High, Leakage (LTC2935-1)
Reset Timeout Period
–200μA Pull-Down Current
0.7 • V
140
V
nA
OH
CC
I
t
V , V = 3.6V
RST PFO
1
10
OH
RST
200
260
ms
Note ±: 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 21 All currents into pins are positive, all voltages are referenced to
GND unless otherwise noted.
Note 31 Guaranteed by design. Characterized, but not production tested.
TYPICAL PERFORMANCE CHARACTERISTICS ꢅA = 25°C, unless otherwise noted1
Normalized Reset and Power-Fail
ꢅhresholds ꢄs ꢅemperature
Comparator Underꢄoltage
Glitch Immunitꢃ
Supplꢃ Current ꢄs Supplꢃ Voltage
1000
800
600
400
200
0
1.015
1.010
1.005
1.000
0.995
0.990
0.985
3.0
2.5
2.0
1.5
1.0
0.5
0
S0 = S1 = S2 = GND
V
= 3.6V
CC
85°C
COMPARATORS PULL DOWN
ABOVE CURVE
25°C
–40°C
0
2
3
4
5
6
–50
0
25
50
75
100
1
–25
0.1
1
10
100
V
(V)
TEMPERATURE (°C)
CC
COMPARATOR OVERDRIVE (%)
2935 G01
2935 G02
2935 G03
Reset ꢅimeout Period
ꢄs ꢅemperature
Voltage Output Low ꢄs Pull-Up
Voltage Output High ꢄs Pull-Down
Current ꢁRST, PFOx
Current ꢁRST, PFOx
260
240
220
200
180
160
140
3.6
3.5
100
80
60
40
20
0
V
= 3.6V
LTC2935-2
V
= 3V
CC
CC
85°C
V
= 3.6V
CC
25°C
–40°C
25°C
–40°C
3.4
3.3
3.2
85°C
–50
0
25
50
75
100
–25
0
–0.4
–0.6
–0.8
–1
–0.2
0
2
3
4
5
1
TEMPERATURE (°C)
PULL-DOWN CURRENT (mA)
PULL-UP CURRENT (mA)
2935 G04
2935 G06
2935 G05
2935fa
4
LTC2935
TYPICAL PERFORMANCE CHARACTERISTICS ꢅA = 25°C, unless otherwise noted1
Supplꢃ Current ꢄs S0, S±, S2
Input Voltage
Supplꢃ Current ꢄs MR Input Voltage
250
200
150
100
50
5
4
3
2
1
0
V
= 3.6V
V
= 3.6V
CC
CC
0
1
1.5
2
2.5
3
4
1
1.5
2
2.5
3
4
0
0.5
3.5
0
0.5
3.5
S0, S1, S2 INPUT VOLTAGE (V)
MR INPUT VOLTAGE (V)
2935 G07
2935 G08
PIN FUNCTIONS
EꢂposedPadꢁDFNOnlꢃx:ExposedPadmaybeleftfloating
or connected to device ground.
RST:ResetOutput.RSTpullslowwhenV fallsbelowthe
CC
reset threshold. RST is released 200ms after V exceeds
CC
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.
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,
S2, S±, S0: Threshold Selection Inputs. Tie to GND or
V
forrequiredresetthreshold. SeetheFallingThreshold
CC
RST returns high after 200ms. Tie to V if unused.
CC
Selection Table on page 1 for settings.
PFO: Power-Fail Output. PFO pulls low when V falls
CC
V : Power Supply and Monitored Voltage Input. Bypass
CC
below the power-fail threshold. The power-fail thresh-
V
CC
with a 0.1μF capacitor to GND.
old is above the configured falling reset threshold by a
pre-determined margin. PFO is released when V rises
CC
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.
2935fa
5
LTC2935
BLOCK DIAGRAM
LTC2935-2/LTC2935-4
MR
V
CC
900k
V
CC
RST
RC
–
+
RESET
DELAY
S0
S1
S2
LTC2935-2/LTC2935-4
V
CC
0.4V
PC
PFO
+
–
GND
2935 BD
TIMING DIAGRAM
V
PFT
V
RTF
V
CC
PFO
RST
MR
t
t
RST
RST
2935 TD
t
PD
2935fa
6
LTC2935
APPLICATIONS INFORMATION
VOLꢅAGE MONIꢅORING
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.
Unmanaged power can cause various system problems.
Atpower-up,voltagefluctuationaroundcriticalthresholds
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 dem-
onstrates the transient amplitude and width required to
switch the comparators.
Few, if any external components are necessary for reliable
operation. However, a decoupling capacitor between V
and ground is recommended (0.01μF minimum).
CC
ꢅhreshold Configuration
The LTC2935 monitors and compares the V voltage
CC
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. Thelowerthreshold(reset)isthelevelatwhichthe
RST output pulls low. Use system requirements to choose
the appropriate reset threshold from Table 1.
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 volt-
age) does not add to the loading problem. When voltage
ꢅable ±1 Falling ꢅhreshold Selection
LꢅC2935-±/LꢅC2935-2
LꢅC2935-3/LꢅC2935-4
is initially applied to V , RST and PFO pull low once there
CC
RESEꢅ POWER-FAIL
RESEꢅ POWER-FAIL
is enough voltage to turn on the pull-down devices (1V
ꢅHRESHOLD ꢅHRESHOLD ꢅHRESHOLD ꢅHRESHOLD
ꢁVx
ꢁVx
ꢁVx
ꢁVx
S2 S± S0
Low Low Low
Low Low High
Low High High
Low High Low
High High Low
High Low Low
High Low High
High High High
maximum).
3.30
3.15
3.00
2.85
2.70
2.55
2.40
2.25
3.45
3.30
3.15
3.00
2.85
2.70
2.55
2.40
2.44
2.32
2.20
2.08
1.96
1.84
1.72
1.60
2.56
2.44
2.32
2.20
2.08
1.96
1.84
1.72
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 V rises
CC
above the power-fail threshold plus 2.5% hysteresis. PFO
is typically used in signal preparation for controlled shut-
down. 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.
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.
If the monitored voltage drops below the reset threshold,
RSTpullslowuntilV risesabovetheresetthresholdplus
CC
5% hysteresis. This may occur through battery charging
2935fa
7
LTC2935
APPLICATIONS INFORMATION
Selecting Output Logic Stꢃle
undeterminedvoltageswhenconnectedtohighimpedance
(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
fromoutputtogroundissatisfactoryformostapplications.
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.
The LTC2935 status outputs are available in two op-
tions: 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 V (5.5V maximum),
CC
which is not always possible with inferior battery supervi-
sors, due to internal clamps. When the status outputs are
low, power is dissipated in the pull-up resistors. Recom-
mended resistor values lie in the range between 10k and
470k.Figure1demonstratestypicalLTC2935-1/LTC2935-3
RST output behavior.
Manual Reset Input
When V is above its reset threshold, and the manual
CC
resetinput(MR)ispulledlow,theRSToutputisforcedlow.
RST remains low for 200ms after the manual reset input is
released and pulled high. The manual reset input is pulled
The active pull-up options (LTC2935-2/LTC2935-4) elimi-
nate the need for external pull-up resistors on the status
outputs. Integrated pull-up devices pull the outputs up to
up internally through 900k to V . If external leakage cur-
CC
rents have the ability to pull down the manual reset input
below its logic threshold, a lower value pull-up resistor,
V . Actively pulled up outputs may not be driven above
CC
placed between V and MR will fix the problem.
V .
CC
CC
Input MR is often pulled down through a pushbutton
switch requiring human contact. If extended ESD toler-
ance is required, series resistance between the switch and
the input is recommended. For most applications, a 10k
resistor provides sufficient current limiting.
Some applications require the RST and/or PFO outputs to
be valid with V down to ground. Active pull-up handles
CC
this requirement with the addition of an external resistor
from the output to ground. The resistor provides a path
forleakagecurrents,preventingtheoutputfromfloatingto
3.5
3.5
LTC2935-1
LTC2935-2
S2 = GND
S2 = GND
3.0
3.0
S1 = S0 = V
CC
S1 = S0 = V
CC
2.5
2.5
2.0
1.5
1.0
0.5
2.0
1.5
1.0
0.5
0
0
1
1.5
V
2
2.5
3
3.5
0
0.5
1
1.5
V
2
2.5
3
3.5
0
0.5
(V)
2935 F01
(V)
2935 F02
CC
CC
Figure ±1 RST ꢄs VCC with ±0k Pull-Up
Figure 21 RST ꢄs VCC
2935fa
8
LTC2935
TYPICAL APPLICATIONS
Batterꢃ Monitor with Interface to Low Voltage Logic
3μA LDO
1.8V
IN
SHDN GND
OUT
ADJ
LT3009
1.18M
590k
1μF
100k
100k
V
V
DD
CC
+
S0
S1
S2
PFO
RST
NMI
Li-Ion
0.1μF
LTC2935-1
GND
μP
R
*
ESD
10k
MR
RST
MANUAL
PB1
RESET
2935 TA02
POWER FAIL FALLING THRESHOLD = 3.15V
RESET FALLING THRESHOLD = 3.00V
PUSHBUTTON
*OPTIONAL RESISTOR FOR ADDED ESD PROTECTION
Alkaline Cell Stack Voltage Monitor
V
MR
PFO
CC
+
+
+
S0
S2
S1
LOW BATTERY
SYSTEM RESET
1.5V
1.5V
1.5V
0.1μF
LTC2935-2
GND
RST
2935 TA03
POWER FAIL FAIL THRESHOLD = 2.55V
RESET THRESHOLD = 2.40V
Coin Cell Voltage Monitor
V
MR
PFO
CC
+
S2
S1
S0
LOW BATTERY
SYSTEM RESET
CR2032
0.1μF
LTC2935-2
GND
RST
2935 TA04
POWER FAIL FAIL THRESHOLD = 2.70V
RESET THRESHOLD = 2.55V
2935fa
9
LTC2935
PACKAGE DESCRIPTION
DC Package
8-Lead Plastic DFN ꢁ2mm × 2mmx
(Reference LTC DWG # 05-08-1719 Rev Ø)
0.70 0.05
2.55 0.05
0.64 0.05
1.15 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 = 0.115
TYP
5
8
R = 0.05
TYP
0.40 0.10
PIN 1 NOTCH
2.00 0.10 0.64 0.10
(4 SIDES)
(2 SIDES)
R = 0.20 OR
0.25 × 45°
CHAMFER
PIN 1 BAR
TOP MARK
(SEE NOTE 6)
(DC8) DFN 0106 REVØ
4
1
0.23 0.05
0.45 BSC
0.75 0.05
0.200 REF
1.37 0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
0.00 – 0.05
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
ꢅS8 Package
8-Lead Plastic ꢅSOꢅ-23
(Reference LTC DWG # 05-08-1637)
2.90 BSC
(NOTE 4)
0.52
MAX
0.65
REF
1.22 REF
1.50 – 1.75
(NOTE 4)
2.80 BSC
1.4 MIN
3.85 MAX 2.62 REF
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
DATUM ‘A’
0.01 – 0.10
1.00 MAX
0.30 – 0.50 REF
1.95 BSC
0.09 – 0.20
(NOTE 3)
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
11
LTC2935
TYPICAL APPLICATION
Portable Deꢄice Batterꢃ Monitor
3μA LDO
1.8V
IN
SHDN GND
OUT
ADJ
LT3009
V
CC
MR
1.18M
590k
100k
+
S0
Li-Ion
0.1μF
1μF
S1
S2
RST
LTC2935-1
GND
100k
LOW BATTERY
EARLY WARNING
PFO
2935 TA05
POWER FAIL FALLING THRESHOLD = 3.15V
RESET FALLING THRESHOLD = 3.00V
RELATED PARTS
PARꢅ NUMBER
LTC690
DESCRIPꢅION
COMMENꢅS
5V Supply Monitor, Watchdog Timer and Battery Backup
3.3V Supply Monitor, Watchdog Timer and Battery Backup
5V Supply Monitor, Watchdog Timer and Pushbutton Reset
Micropower Triple Supply Monitor for 5V/2.5V, 3.3V and ADJ
Micropower Triple Supply Monitor for 2.5V/5V, 3.3V and ADJ
Micropower Triple Supply Monitor with Open-Drain Reset
Micropower Triple Supply Monitor with Open-Drain Reset
Micropower Triple Supply Monitor with Push-Pull Reset Output
Programmable Quad Supply Monitor
4.65V Threshold
LTC694-3.3
LTC1232
LTC1326
LTC1726
LTC1727
LTC1728
LTC1985
LTC2900
LTC2901
LTC2902
LTC2903
2.9V Threshold
4.37V/4.62V Threshold
4.725V, 3.118V, 1V Threshold ( 0.75%) and ADJ
Adjustable Reset and Watchdog Timeouts
Individual Monitor Outputs in MSOP
5-Lead SOT-23 Package
5-Lead SOT-23 Package
Adjustable Reset, 10-Lead MSOP and DFN Packages
Adjustable Reset and Watchdog Timer
Adjustable Reset and Tolerance
Programmable Quad Supply Monitor
Programmable Quad Supply Monitor
Precision Quad Supply Monitor
6-Lead SOT-23 Package
LTC2904/LTC2905/ Three-State Programmable Precision Dual Supply Monitor
LTC2906/LTC2907
8-Lead SOT-23 and DFN Packages
LTC2908
LTC2909
Precision Six-Supply Monitor (Four Fixed and Two Adjustable)
8-Lead TSOT-23 and DFN Packages
Precision Triple/Dual Input UV, OV and Negative Voltage Monitor Shunt Regulated V Pin, Adjustable Threshold and Reset,
CC
8-Lead SOT-23 and DFN Packages
LTC2910
Octal Positive/Negative Voltage Monitor
Separate V Pin, Eight Inputs, Up to Two Negative Monitors
CC
Adjustable Reset Timer, 16-Lead SSOP and DFN Packages
LTC2912/LTC2913/ Single/Dual/Quad UV and OV Voltage Monitors
LTC2914
Separate V Pin, Adjustable Reset Timer
CC
LTC2915/LTC2916/ Single Voltage Supervisors with 27 Pin-Selectable Thresholds
LTC2917/LTC2918
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
LT 0609 REV A • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
12
●
●
© LINEAR TECHNOLOGY CORPORATION 2008
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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