LTC2915CDDB-1-TRPBF [Linear]
Voltage Supervisor with 27 Selectable Thresholds; 电压监控器， 27个可选择阈值
| 型号： | LTC2915CDDB-1-TRPBF |
| 厂家： | 
Linear |
| 描述： | Voltage Supervisor with 27 Selectable Thresholds |
| 文件： | 总12页 (文件大小：143K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC2915/LTC2916
Voltage Supervisor with
27 Selectable Thresholds
FEATURES
DESCRIPTION
The LTC®2915/LTC2916 are low voltage single-supply
monitors with selectable thresholds. The parts operate
from 1.5V to 5.5V and consume a quiescent current of
only 30μA.
n
9 Selectable Supply Voltages
12V, 5V, 3.3V, 2.5V, 1.8V
1.5V, 1.2V, 1.0V, +ADJ (0.5V)
n
3 Selectable Tolerances
–5%, –10%, –15% (LTC2915)
Two three-state inputs select one of nine internally pro-
grammedthresholdswithouttheneedforexternalresistors.
FortheLTC2915,anadditionalthree-stateinputdetermines
the tolerance (–5%, –10%, –15%). The tolerance for the
LTC2916isfixedat–5%.Thresholdaccuracyisguaranteed
at 1.5% over the entire operating temperature range.
Glitch filtering ensures reliable reset operation without
false triggering.
n
Manual Reset Input (LTC2916)
n
1.5V to 5.5V Supply Operation
n
6.2V Shunt Regulator for High Voltage Operation
n
Guaranteed Operation to 125˚C
n
Guaranteed Threshold Accuracy: 1.5%
n
Low Quiescent Current: 30μA Typical
n
Power Supply Glitch Immunity
n
Guaranteed RST for V ≥ 0.8V
CC
Low Profile (1mm) 8-Lead TSOT-23 (ThinSOTTM) and
n
The reset timeout may be set to 200ms or adjusted using
an external capacitor. A separate manual reset input on the
LTC2916 allows a simple push button interface.
(3mm × 2mm) DFN Packages
APPLICATIONS
Operation to 125°C makes the LTC2915 and LTC2916
suitable for automotive applications.
L, LT, LTC and LTM 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.
n
Handheld Devices
n
Cell Phone Base Stations
n
Automotive Control Systems
Network Servers
n
n
Optical Networking Systems
TYPICAL APPLICATION
1.8V, –5% Tolerance Supply Monitor
Monitor Selection Table
1.8V
NOMINAL VOLTAGE
SEL1
SEL2
12V
5V
V
V
V
V
CC
CC
CC
CC
0.1μF
V
Open
GND
CC
10k
V
CC
μP
RESET
3.3V
LTC2916
RST
VM
RT
2.5V
Open
Open
Open
GND
GND
GND
V
CC
SEL1
SEL2
1.8V
Open
GND
t
= 200ms
RST
29156 TA01
1.5V
MR
GND
1.2V
V
CC
1V
Open
GND
ADJ (0.5V)
29156fa
1
LTC2915/LTC2916
(Notes 1, 2)
ABSOLUTE MAXIMUM RATINGS
Terminal Voltages
Operating Temperature Range
V
(Note 3).......................................... –0.3V to 5.7V
LTC2915C/LTC2916C ............................... 0°C to 70°C
LTC2915I/LTC2916I.............................. –40°C to 85°C
LTC2915H/LTC2916H......................... –40°C to 125°C
Storage Temperature Range................... –65°C to 150°C
TS8 Lead Temperature (Soldering, 10 sec)........... 300°C
CC
SEL1, SEL2, TOL, MR, RST .................. –0.3V to 7.5V
VM......................................................... –0.3V to 15V
RT.............................................–0.3V to (V + 0.3)V
CC
Terminal Currents
V
(Note 3)....................................................... 5mA
CC
PIN CONFIGURATION
TOP VIEW
TOP VIEW
GND
TOL/MR
SEL1
1
2
3
4
8
7
6
5
RST
RT
VM 1
SEL1 2
TOL/MR 3
GND 4
8 V
CC
7 SEL2
6 RT
9
SEL2
VM
V
CC
5 RST
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
DDB PACKAGE
8-LEAD (3mm s 2mm) PLASTIC DFN
TOL FOR LTC2915
MR FOR LTC2916
TOL FOR LTC2915
T
= 150°C, θ = 250°C/W
JMAX
JA
MR FOR LTC2916
T
= 150°C, θ = 76°C/W
JMAX
JA
EXPOSED PAD (PIN 9) PCB GND CONNECTION OPTIONAL
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC2915CTS8-1#PBF
LTC2915ITS8-1#PBF
LTC2915HTS8-1#PBF
LTC2915CDDB-1#PBF
LTC2915IDDB-1#PBF
LTC2915HDDB-1#PBF
LTC2915CTS8-1#TRPBF
LTC2915ITS8-1#TRPBF
LTC2915HTS8-1#TRPBF
LTC2915CDDB-1#TRPBF
LTC2915IDDB-1#TRPBF
LTC2915HDDB-1#TRPBF
LTCVQ
LTCVQ
LTCVQ
LCVR
LCVR
LCVR
8-Lead TSOT-23
8-Lead TSOT-23
8-Lead TSOT-23
8-Lead (3mm × 2mm) Plastic DFN
8-Lead (3mm × 2mm) Plastic DFN
8-Lead (3mm × 2mm) Plastic DFN
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC2916CTS8-1#PBF
LTC2916ITS8-1#PBF
LTC2916HTS8-1#PBF
LTC2916CDDB-1#PBF
LTC2916IDDB-1#PBF
LTC2916HDDB-1#PBF
LTC2916CTS8-1#TRPBF
LTC2916ITS8-1#TRPBF
LTC2916HTS8-1#TRPBF
LTC2916CDDB-1#TRPBF
LTC2916IDDB-1#TRPBF
LTC2916HDDB-1#TRPBF
LTDCW
LTDCW
LTDCW
LDCX
LDCX
LDCX
8-Lead TSOT-23
8-Lead TSOT-23
8-Lead TSOT-23
8-Lead (3mm × 2mm) Plastic DFN
8-Lead (3mm × 2mm) Plastic DFN
8-Lead (3mm × 2mm) Plastic DFN
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard 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/
29156fa
2
LTC2915/LTC2916
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 2.5V, unless otherwise noted. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
l
l
l
V
V
V
Supply Voltage for Guaranteed RST Low RST Driven Low
0.8
V
V
V
CC(MIN)
Supply Undervoltage Lockout
1.5
7.0
CC(UVLO)
CC(SHUNT)
Shunt Regulation Voltage
Pin Current
I
= 0.5mA
5.7
6.2
VCC
l
l
I
CC
V
SEL1, SEL2, TOL, MR = Open
30
45
50
80
μA
μA
CC
SEL1, SEL2, TOL = GND (LTC2915)
MR = V (LTC2916)
CC
Monitor Input (VM)
l
l
l
V
V
V
V
V
V
V
V
V
12V, 5% Reset Threshold
12V, 10% Reset Threshold
12V, 15% Reset Threshold
11.04
10.44
9.84
11.22
10.62
10.02
11.40
10.80
10.20
V
V
V
MT120
MT50
MT33
MT25
MT18
MT15
MT12
MT10
MTADJ
l
l
l
5V, 5% Reset Threshold
5V, 10% Reset Threshold
5V, 15% Reset Threshold
4.600
4.350
4.100
4.675
4.425
4.175
4.750
4.500
4.250
V
V
V
l
l
l
3.3V, 5% Reset Threshold
3.3V, 10% Reset Threshold
3.3V, 15% Reset Threshold
3.036
2.871
2.706
3.086
2.921
2.756
3.135
2.970
2.805
V
V
V
l
l
l
2.5V, 5% Reset Threshold
2.5V, 10% Reset Threshold
2.5V, 15% Reset Threshold
2.300
2.175
2.050
2.338
2.213
2.088
2.375
2.250
2.125
V
V
V
l
l
l
1.8V, 5% Reset Threshold
1.8V, 10% Reset Threshold
1.8V, 15% Reset Threshold
1.656
1.566
1.476
1.683
1.593
1.503
1.710
1.620
1.530
V
V
V
l
l
l
1.5V, 5% Reset Threshold
1.5V, 10% Reset Threshold
1.5V, 15% Reset Threshold
1.380
1.305
1.230
1.403
1.328
1.253
1.425
1.350
1.275
V
V
V
l
l
l
1.2V, 5% Reset Threshold
1.2V, 10% Reset Threshold
1.2V, 15% Reset Threshold
1.104
1.044
0.984
1.122
1.062
1.002
1.140
1.080
1.020
V
V
V
l
l
l
1V, 5% Reset Threshold
1V, 10% Reset Threshold
1V, 15% Reset Threshold
0.920
0.870
0.820
0.935
0.885
0.835
0.950
0.900
0.850
V
V
V
l
l
l
ADJ (0.5V), 5% Reset Threshold
ADJ (0.5V), 10% Reset Threshold
ADJ (0.5V), 15% Reset Threshold
460.0
435.0
410.0
467.5
442.5
417.5
475.0
450.0
425.0
mV
mV
mV
l
l
R
VM Input Impedance (Note 4)
ADJ Input Current
Fixed Threshold Modes
VM = 0.5V
0.5
8
MΩ
VM
I
15
nA
VM(ADJ)
Three-State Inputs (SEL1, SEL2), (TOL, LTC2915)
l
l
V
Low Level Input Voltage
High Level Input Voltage
Pin Voltage when Open
Allowable Leakage in Open State
Pin Input Current
0.5
V
V
TPIN,LOW
V
1.4
TPIN,HIGH
V
TPIN,Z
I
= 0μA
0.9
V
TPIN
l
l
I
I
5
μA
μA
TPIN,Z
V
= 0V, V
CC
20
TPIN,H/L
TPIN
29156fa
3
LTC2915/LTC2916
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 2.5V, unless otherwise noted. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Reset Timer Control (RT)
l
l
l
l
I
I
I
RT Pull-Up Current
V
RT
V
RT
V
RT
V
RT
= 0.25V
= 1.1V
–2
2
–3
3
–4
4
μA
μA
RT(UP)
RT Pull-Down Current
RT(DOWN)
RT(INT)
Internal RT VCC Detect Current
RT Internal Timer Threshold
= V
1
8
μA
CC
V
Rising, Referenced to V
–100
–160
–300
mV
RT(INT,LH)
CC
Reset Output (RST)
l
l
l
t
t
t
Internal Reset Timeout Period
Adjustable Reset Timeout Period
V
C
= V
CC
150
16
200
20
260
25
ms
ms
μs
RST(INT)
RST(EXT)
UV
RT
= 2.2nF
RT
VM Undervoltage Detect to RST
Asserted
VM Less Than Reset Threshold
10
80
150
V
by More Than 5%
MTX
l
l
l
V
Output Voltage Low RST
V
CC
V
CC
V
CC
= 3.3V, I = 2.5mA
RST
0.15
0.15
0.05
0.4
0.3
0.2
V
V
V
OL
= 1V, I
= 100μA
RST
= 0.8V, I
= 15μA
RST
l
I
RST Output Voltage High Leakage
RST = V
1
μA
OH(RST)
CC
Manual Reset Input (LTC2916)
l
l
l
l
V
V
Input Low Voltage
Input High Voltage
Pull Up Resistance
Pulsewidth
0.2 • V
150
V
V
IL
CC
0.8 • V
50
IH
CC
R
100
kΩ
ns
PU
t
250
PW
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 3: V maximum pin voltage is limited by input current. Since the
CC
V
CC
pin has an internal 6.2V shunt regulator, a low impedance supply
which exceeds 5.7V may exceed the rated terminal current. Operation
from higher voltage supplies requires a series dropping resistor. See
Applications Information.
Note 2: All currents into pins are positive; all voltages are referenced to
GND unless otherwise noted.
Note 4: Input impedance is dependent on the configuration of the SEL
pins.
TIMING DIAGRAM
Monitor Input Timing
V
MTx
VM
t
t
RST
UV
RST
1V
29156 TD01
29156fa
4
LTC2915/LTC2916
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C unless otherwise noted.
Threshold Voltage vs
Temperature
Quiescent Supply Current vs
Temperature
Allowable Glitch Duration vs
Magnitude
1.5
1.0
0.5
0
300
250
200
150
100
50
40
35
30
25
SEL1 = 0V
SEL2 = 2.5V
TOL = OPEN
V
V
= 5.5V
= 2.5V
CC
CC
V
V
RESET OCCURS
ABOVE CURVE
MTADJ
V
MT25
–0.5
–1.0
–1.5
V
= 1.5V
CC
MT120
20
0
50
TEMPERATURE (°C)
100 125
–50 –25
0
25
75
–50 –25
0
25
50
75 100 125
0.1
1
10
100
TEMPERATURE (°C)
GLITCH PERCENTAGE PAST THRESHOLD (%)
29156 G01
29156 G02
29156 G03
Internal Reset Timeout Period vs
Temperature
Shunt Regulation Voltage vs
Temperature
Shunt Regulation Voltage vs
Supply Current
6.4
6.3
6.2
6.1
250
230
210
190
170
150
7.0
6.8
6.6
6.4
6.2
6.0
RT = V
CC
I
= 5mA
CC
I
= 1mA
CC
I
CC
= 100μA
–50 –25
0
25
50
75 100 125
0.01
0.1
1
10
100
–50 –25
0
25
50
75 100 125
TEMPERATURE (°C)
TEMPERATURE (°C)
SUPPLY CURRENT, I (mA)
CC
29156 G05
29156 G06
29156 G04
RST Output Voltage vs VCC
RST Pull-Down Current vs VCC
RST VOL vs IRST
6
5
1.0
0.8
0.6
6
5
100k PULL-UP TO V
CC
NO PULL-UP R
= 2.5V
SEL1 = SEL2 = TOL = 0V
V
CC
V
M
= 0.5V
T
= 125°C
= –40°C
A
4
3
4
3
RST AT 150mV
RST AT 50mV
T
= 25°C
A
0.4
0.2
0
2
1
0
2
1
0
T
A
0
1
2
3
4
5
0
2
4
6
8
10
0
1
2
3
4
5
SUPPLY VOLTAGE, V (V)
SUPPLY VOLTAGE, V (V)
I
(mA)
CC
CC
RST
29156 G07
29156 G09
29156 G08
29156fa
5
LTC2915/LTC2916
PIN FUNCTIONS (TSOT/DFN)
GND (Pin 4/Pin 1): Device Ground.
TOL (Pin 3/Pin 2) (LTC2915 only): Three-State Input
for Supply Tolerance Selection (–5%, –10% or –15%).
Controls the tolerance band at which the VM supply is
MR (Pin 3/Pin 2) (LTC2916 only): Manual Reset Input
(Active Low). A low level on the MR input causes the part
to issue a reset, which is released one reset timeout after
the input goes high. The pin has an internal 100k pull-up
monitored. Connect to V , GND, or leave unconnected
CC
in open state. (See Table 2).
to V , and thus may interface directly to a momentary
V
(Pin 8/Pin 5): Power Supply Input. Bypass this pin
CC
CC
pushbutton. Leave open if unused.
to ground with a 0.1μF ceramic capacitor. A minimum of
1.5V on V ensures that the part is out of under voltage
CC
RST (Pin 5/Pin 8): Open Drain RST Output. Asserts low
when VM is below the threshold selected by SEL1, SEL2
and TOL input pins. Held low for an adjustable timeout
after VM input is above threshold.
lockout and that the voltage thresholds are accurate.
Operates as a direct supply input for voltages up to 5.5V.
Operates as a shunt regulator for supply voltages greater
than 5.7V and should have a resistor between this pin and
RT (Pin 6/Pin 7): Reset Timeout Control Pin. Attach an
the supply to limit V input current to no greater than
CC
external Capacitor (C ) to GND to set a reset timeout of
5mA. When used without a current-limiting resistor, pin
RT
9ms/nF. Floating RT generates a reset timeout of approxi-
voltage must not exceed 5.7V.
mately 400μs. Tie RT to V to generate a reset timeout
CC
VM (Pin 1/Pin 4): Voltage Monitor Input to RST Compara-
tor. SEL1, SEL2 and TOL inputs select the exact threshold
that asserts the RST output.
of approximately 200ms.
SEL1, SEL2 (Pins 2, 7/Pins 3, 6): Monitor Voltage Select
Three-State Inputs. SEL1 and SEL2 control the nominal
Exposed Pad (Pin 9, DFN Only): Exposed Pad may be left
open or connected to device ground.
thresholdvoltagethatVMissettomonitor.ConnecttoV ,
CC
GND or leave unconnected in open state. (See Table 1).
BLOCK DIAGRAM
LTC2915
TOL
LTC2916
SEL1
SEL2
MR
RT
V
CC
3 STATE
DECODE
V
CC
V
CC
V
CC
DETECT
100k
6.2V
MONITOR
DIVIDER
MATRIX
VM
INTERNAL
200ms TIMER
RST
–
+
RESET
DRIVER LOGIC
REFERENCE
DIVIDER
MATRIX
GND
+
0.5V
ADJUSTABLE
RESET TIMER
–
29156 BD
29156fa
6
LTC2915/LTC2916
APPLICATIONS INFORMATION
Supply Monitoring
The SEL1 and SEL2 three-state input pins should be con-
nected to GND, V or left unconnected during normal
CC
The LTC2915/LTC2916 are low voltage single supply
monitorswithselectablethresholds.Twothree-stateinputs
select one of nine internally programmed thresholds. For
theLTC2915, athirdthree-stateinputselectsthetolerance
at which the supply connected to the VMpin is monitored
(–5%, –10%, –15%). The tolerance for the LTC2916 is
fixed at –5%. Threshold accuracy is guaranteed at 1.5%
over the entire operating temperature range.
operation. Notethatwhenleftunconnected, themaximum
leakage allowable from the pin to either GND or V is
CC
5μA.
The tolerance at which the monitored supply is measured
is set by the TOL pin (LTC2915 only), as shown in Table 2.
If desired (e.g. for margining purposes), the TOL pin may
be driven by a three-state buffer. That three-state buffer
must have a V and V which meet the V and V of
OL
OH
IL
IH
The LTC2915/LTC2916 asserts the RST output low when
the TOL pin specified in the Electrical Characteristics, and
VM is below the programmed threshold, and for a reset
maintain less than 5μA of leakage in the open state.
timeout(t )afterVMgoesabovethethreshold.Thereset
RST
timeout can be configured to use an internal timer with no
external components, or an adjusted timer programmed
by placing an external capacitor from RT to ground.
Threshold Accuracy
The trip threshold for VM is selected by configuring the
three-stateinputpins. Whenusingtheadjustableinput, an
external resistive divider sets the trip threshold, allowing
the user complete control over the trip point. Selection of
this trip voltage is crucial to the reliability of the system.
Power-Up
V
powers the drive circuits for the RST pin. Therefore,
CC
as soon as V reaches 0.8V during power up, the RST
CC
output asserts low.
Table 1. Voltage Threshold Settings
Until V reaches the undervoltage lockout threshold
NOMINAL VOLTAGE
SEL1
SEL2
CC
(guaranteed less than 1.5V), RST is held low regardless
12V
V
V
V
V
CC
CC
CC
CC
of the state of VM.
5V
Open
GND
3.3V
Once V is above the under voltage lockout threshold
CC
2.5V
Open
Open
Open
GND
GND
GND
V
and VM is above the programmed threshold, the reset
CC
timer is started. After the reset timeout (t ), the open
1.8V
Open
GND
RST
drain pull-down releases RST and the external pull-up
1.5V*
resistor pulls high.
1.2V*
V
CC
1V*
Open
GND
Power-Down
ADJ* (0.5V)
On power-down, once VM drops below its threshold or
CC
logic low.
*Require a separate supply for V
CC
V
drops below the undervoltage lockout, RST asserts
Table 2. System Voltage Tolerance Settings
TOLERANCE
–5%
TOL
Monitor Threshold Control
V
CC
The monitor threshold on the VM pin is controlled by
the SEL1, SEL2 and TOL three-state pins. The SEL1 and
SEL2 pins select one of nine preset nominal voltages
(including one externally adjustable threshold) as shown
in Table 1.
–10%
Open
GND
–15%
29156fa
7
LTC2915/LTC2916
APPLICATIONS INFORMATION
Any power supply has some tolerance band within which
it is expected to operate (e.g. 5V 10%). It is generally
undesirablethatasupervisorissuearesetwhenthepower
supply is inside this tolerance band. Such a “nuisance”
reset reduces reliability by preventing the system from
functioning under normal conditions.
period, the timer resets and begins again when the supply
next becomes valid.
While the reset timeout is useful at preventing toggling
of the reset output in most cases, it is not effective at
preventing nuisance resets due to short glitches (due to
load transients or other effects) on a valid supply.
Topreventnuisanceresets,thesupervisorthresholdmust
be guaranteed to lie outside the power supply tolerance
band. To ensure that the threshold lies outside the power
supplytolerancerange,thenominalthresholdmustlieout-
side that range by the monitor’s accuracy specification.
Toreducesensitivitytotheseshortglitches,thecomparator
hasadditionalanti-glitchcircuitry.Anytransientattheinput
of the comparator needs to be of sufficient magnitude and
duration t before it can change the monitor state.
UV
The combination of the reset timeout and anti-glitch cir-
cuitry prevents spurious changes in output state without
sacrificing threshold accuracy.
All 27 of the selectable thresholds have the same relative
threshold accuracy of 1.5% of the programmed nominal
input voltage (over the full operating temperature range).
Considertheexampleofmonitoringa5Vsupplywitha10%
tolerance. The nominal threshold internal to the LTC2915
is 11.5% below the 5V input at 4.425V. With 1.5% ac-
curacy, the trip threshold range is 4.425V 75mV over
temperature(i.e. 10%to13%below5.0V). Themonitored
system must thus operate reliably down to 4.35V or 13%
below 5.0V over temperature.
Adjustable Input
When the monitor threshold is configured as ADJ, the
internal comparator input is connected to the pin without
a resistive divider, and the pin is high-impedance. Thus,
any desired threshold may be chosen by attaching VM to
a tap point on an external resistive divider between the
monitored supply and ground, as shown in Figure 1.
Glitch Immunity
The reference input of the comparator is controlled by the
tolerance pin. The external resistive divider should make
the voltage at VM = 0.5V when the supply is at nominal
value. The actual threshold of VM accounts for the sup-
ply tolerance of 1.5% guaranteed over the full operating
temperature range. The resulting tolerances are –6.5%,
–11.5%, –16.5% which correspond to 0.468V, 0.443V,
0.418V repectively.
The above discussion is concerned only with the DC
value of the monitored supply. Real supplies also have
relatively high-frequency variation, from sources such as
loadtransients,noise,andpickup.Thesevariationsshould
not be considered by the monitor in determining whether
a supply voltage is valid or not. The variations may cause
spurious outputs at RST, particularly if the supply voltage
is near its trip threshold.
V
MON
Twotechniquesareusedtocombatspuriousresetwithout
sacrificing threshold accuracy. First, the timeout period
helps prevent high-frequency variation whose frequency
R2
VM
–
+
R1
is above 1/ t
from appearing at the RST output.
RST
When the voltage at VM goes below the threshold, the
RST pin asserts low. When the supply recovers past
the threshold, the reset timer starts (assuming it is not
disabled), and RST does not go high until it finishes. If
the supply becomes invalid any time during the timeout
+
0.5V
–
29156 F01
Figure 1. Setting the Trip Point Using the Adjustable Threshold
29156fa
8
LTC2915/LTC2916
APPLICATIONS INFORMATION
Typically, the user will pick a value of R1 based on accept-
able current draw. Current used by the resistor divider will
be approximately
Leaving RT open with no external capacitor generates a
reset timeout of approximately 400μs. Shorting RT to V
generates a reset timeout of approximately 200ms.
CC
0.5V
I
⎛
⎞
RST Output Characteristics
R1=
⎜
⎝
⎟
⎠
The DC characteristics of the RST pull-down strength
are shown in the Typical Performance Characteristics
section. RST is an open-drain pin and thus requires an
external pull-up resistor to the logic supply. RST may be
Recommended range of R1 is 1k to 1M. Higher values
of resistance exacerbate the degradation of threshold
accuracy due to leakage currents.
pulled above V , providing the voltage limits of the pin
CC
If the nominal value of the supply being monitored is
are observed.
V
, then
NOM
The open-drain of the RST pin allows for wired-OR con-
nection of several LTC2915/LTC2916s.
R2 = R1(2V
– 1)
NOM
Resistor tolerances must be taken into account when
determining the overall accuracy.
As noted in the discussion of power up and power down,
the circuits that drive RST are powered by V . During a
CC
fault condition, V of at least 1V ensures that RST pulls
CC
Selecting the Reset Timing Capacitor
low.
The reset timeout period can be set to one of two fixed
internal timers or set with a capacitor in order to accom-
modate a variety of applications. Connecting a capacitor,
Manual Reset (LTC2916 Only)
The LTC2916 includes the MR pin for applications where
a manual reset is desired. MR is internally pulled up, al-
lowing it to interface with a push button with no external
componentsrequired.AssertingMRlowwhenRSTishigh,
initiates a reset, resulting in RST being asserted low for
the set reset timeout.
C , between the RT pin and ground sets the reset timeout
RT
period,t .Thefollowingformulaapproximatesthevalue
RST
of capacitor needed for a particular timeout:
C
= t
• 110 [pF/ms]
RT
RST
For example, using a standard capacitor value of 2.2nF
would give 20ms delay.
Shunt Regulator
Figure 2 shows the reset timeout period as a function of
the value of the timer capacitor.
The LTC2915 and LTC2916 contain an internal 6.2V shunt
regulator on the V pin to allow operation from a high
CC
voltage supply. To operate the part from a supply higher
10000
1000
100
10
than 5.7V, the V pin must have a series resistor, R , to
CC
CC
the supply. This resistor should be sized according to the
following equation:
VS(MAX) −5.7V
VS(MIN) −7V
250μA
≤RCC ≤
5mA
where V
and V
are the operating minimum
S(MIN)
S(MAX)
1
and maximum of the supply.
As an example, consider operation from an automobile
battery which might dip as low as 10V or spike to 60V. We
must then pick a resistance between 10.86k and 12k.
0.1
0.001 0.01
0.1
1
10
100 1000
RT PIN CAPACITANCE, C (nF)
RT
29156 F02
Figure 2. Reset Timeout Period vs RT Capacitance
29156fa
9
LTC2915/LTC2916
TYPICAL APPLICATIONS
12V Supply Monitor Powered from 12V, Utilizing
Internal Shunt Regulator with 3.3V Logic Out
5V, –10% Tolerance Supply Monitor with
200ms Internal Reset Timeout
3.3V
12V
3.3V
C
BYPASS
R
R
PU
10k
R
CC
PU
0.1μF
11k
10k
C
V
BYPASS
CC
0.1μF
V
V
CC
CC
V
CC
LTC2915
μP
LTC2915
μP
VM
5V
RST
RST
VM
RST
RST
3.3V
SEL1
SEL2
TOL
GND
SEL1
SEL2
TOL
GND
29156 TA03
29156 TA02
GND
RT
3.3V
GND
RT
C
RT
9V, –15% Tolerance Supply Monitor with 3.3V Logic Out
1V, –15% Tolerance Supply Monitor with 90ms Timeout
3.3V
3.3V
9V
C
BYPASS
C
BYPASS
0.1μF
R
R
PU
PU
0.1μF
10k
10k
R2
866k
V
CC
V
CC
V
CC
V
CC
LTC2915
μP
LTC2915
μP
VM
RST
RST
RST
VM
1V
RST
SEL1
SEL2
TOL
GND
SEL1
SEL2
TOL
GND
29156 TA04
29156 TA05
R1
51.1k
GND
RT
GND
RT
C
C
RT
RT
0.01μF
1.5V Supply Monitor with Tolerance Control for Margining,
–5% Operation with –15% Margining
1.8V, –5% Supply Monitor with Manual Reset
1.8V
3.3V
C
BYPASS
C
BYPASS
R
R
PU
PU
0.1μF
0.1μF
10k
10k
V
CC
V
CC
V
CC
LTC2916
μP
V
CC
VM
RST
RST
LTC2915
μP
SEL1
GND
1.5V
VM
RST
RST
I/O
29156 TA07
SEL2
MR
SEL1
SEL2
GND
–15% –5%
29156 TA08
GND
RT
10k*
GND
RT
MANUAL RESET
PUSHBUTTON
C
RT
C
RT
*OPTIONAL RESISTOR RECOMMENDED TO EXTEND ESD TOLERANCE
29156fa
10
LTC2915/LTC2916
PACKAGE DESCRIPTION
TS8 Package
8-Lead Plastic TSOT-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
DDB Package
8-Lead Plastic DFN (3mm × 2mm)
(Reference LTC DWG # 05-08-1702 Rev B)
0.61 0.05
(2 SIDES)
R = 0.115
0.40 0.10
8
3.00 0.10
(2 SIDES)
TYP
5
R = 0.05
TYP
0.70 0.05
2.55 0.05
1.15 0.05
2.00 0.10
PIN 1 BAR
TOP MARK
PIN 1
(2 SIDES)
R = 0.20 OR
(SEE NOTE 6)
0.25 × 45°
PACKAGE
OUTLINE
0.56 0.05
(2 SIDES)
CHAMFER
4
1
(DDB8) DFN 0905 REV B
0.25 0.05
0.25 0.05
0.75 0.05
0.200 REF
0.50 BSC
2.20 0.05
(2 SIDES)
0.50 BSC
2.15 0.05
(2 SIDES)
0 – 0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING CONFORMS TO VERSION (WECD-1) IN JEDEC PACKAGE OUTLINE M0-229
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
29156fa
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
LTC2915/LTC2916
TYPICAL APPLICATION
Dual Supply Monitor (1.8V and 12V) with Manual Reset and 200ms Reset Timeout
1.8V
C
BYPASS
0.1μF
R
PU
10k
V
CC
V
CC
V
CC
LTC2916
LTC2915
μP
VM
RST
12V
VM
RST
RST
SEL1
SEL2
MR
SEL1
SEL2
TOL
GND
29156 TA10
1.8V
GND
RT
1.8V
GND
RT
1.8V
MANUAL RESET
PUSHBUTTON
RELATED PARTS
PART NUMBER
LTC690
DESCRIPTION
COMMENTS
5V Supply Monitor, Watchdog Timer and Battery Backup
3.3V Supply Monitor, Watchdog Timer and Battery Backup
4.65V Threshold
2.9V Threshold
LTC694-3.3
LTC1232
5V Supply Monitor, Watchdog Timer and Push-Button Reset 4.37V/4.62V Threshold
Micro Power Precision Triple Supply Monitor 4.725V, 2.363V, 3.118V, 1V Threshold ( 0.75%)
Micro Power Triple Supply Monitor for 2.5V/5V, 3.3V and ADJ Adjustable RESET and Watchdog Time-Outs
LTC1326
LTC1726
LTC1727
Micro Power Triple Supply Monitor with Open-Drain Reset
Micro Power Triple Supply Monitor with Open-Drain Reset
Micro Power Triple Supply Monitor with Push-Pull Reset
Programmable Quad Supply Monitor
Individual Monitor Outputs in MSOP
LTC1728
5-Lead SOT-23 Package
LTC1985-1.8
LTC2900
5-Lead SOT-23 Package
Adjustable RESET, 10-Lead MSOP and 3mm × 3mm 10-Lead DFN
Adjustable RESET and Watchdog Timer, 16-Lead SSOP Package
Adjustable RESET and Tolerance, 16-Lead SSOP Package, Margining
6-Lead SOT-23 Package, Ultra Low Voltage Reset
Adjustable RESET and Tolerance, 8-Lead SOT-23 Package
LTC2901
Programmable Quad Supply Monitor
LTC2902
Programmable Quad Supply Monitor
LTC2903
Precision Quad Supply Monitor
LTC2904/LTC2905 3-State Programmable Precision Dual Supply Monitor
LTC2906
LTC2907
LTC2908
LTC2909
LTC2910
LTC2912
Precision Dual Supply Monitor 1 Selectable and 1 Adjustable Separate V Pin, RST/RST Outputs
CC
Precision Dual Supply Monitor 1 Selectable and 1 Adjustable Separate V Pin, Adjustable Reset Timer
CC
Precision Six Supply Monitor (Four Fixed and 2 Adjustable)
Precision Triple/Dual Input UV, OV Monitor
8-Lead SOT-23 and DDB Packages
2 ADJ Inputs, Monitors Negative Voltages
16-Lead SSOP and 5mm × 3mm DFN Packages
8-Lead TSOT and 3mm × 2mm DFN Packages
Octal Positive/Negative Voltage Monitor
Single UV/OV Voltage Monitor, Adjustable UV and OV Trip
Values
LTC2913
LTC2914
Dual UV/OV Voltage Monitor
10-Lead MOSP and 3mm × 3mm DFN Packages
16-Lead SSOP and 5mm × 3mm DFN Packages
Qual UV/OV Positive/Negative Voltage Monitor
29156fa
LT 0108 REV A • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
12
●
●
© LINEAR TECHNOLOGY CORPORATION 2007
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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