LTC2965
100V Micropower Single
Voltage Monitor
FEATURES
DESCRIPTION
Wide Operating Range: 3.5V to 100V
n Wide Monitoring Range: 3.5V to 98V
n Quiescent Current: 7µA
n Adjustable Threshold Range
n Internal High Value Resistive Dividers
n ±1.4% (Max) Threshold Accuracy Over Temperature
n Polarity Selection
n 100V Rated Outputs
n Selectable Built-In Hysteresis
n 16-Lead MS and 8-Lead 3mm × 3mm DFN Packages
The LTC®2965 is a low current, high voltage single channel voltage monitor. Internal high value resistors sense
the input monitor pin providing a compact and low power
solution for voltage monitoring. Two comparator reference
inputs (INH and INL) are included to allow configuration of
a high and low threshold using an external resistive divider
biased from the on-chip reference. A range selection pin
is provided to set the internal resistive divider for 10x or
40x scaling. The thresholds are scaled according to the
range selection settings. Additionally, either INH or INL
can be grounded to enable built-in hysteresis. Polarity
selection pin allows the output to be inverted. The output
is 100V capable and includes a 500k pull-up resistor to
an internal supply.
n
APPLICATIONS
n
n
n
n
Portable Equipment
Battery-Powered Equipment
Telecom Systems
Automotive/Industrial Electronics
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Analog
Devices, Inc. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Undervoltage Monitor
24V
5V
VIN
OUT
INH
91k
3.5V to 24.5V
10x
14V to 98V
40x
24V UNDERVOLTAGE
5V
SYS
LTC2965
INL
Supply Current vs VIN
12
909k
10
PS
RS GND
8
2965 TA01a
POLARITY AND RANGE SELECTION
IVIN (µA)
THRESHOLD
CONFIGURATION
RANGE SELECTION
100k
REF
200k
VIN MONITOR RANGE
6
4
RISING THRESHOLD
FALLING THRESHOLD
HYSTERESIS
RANGE
20.0V
18.2V
1.8V
10x
0
–45°C
25°C
90°C
125°C
RANGE = 40x
OUT = LOW
IREF = 0µA
2
0
20
40
60
VIN (V)
80
100
2965 TA01b
2965fc
For more information www.linear.com/LTC2965
1
LTC2965
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
Input Voltages
VIN........................................................ –0.3V to 140V
PS, RS...................................................... –0.3V to 6V
INH, INL.................................................... –0.3V to 6V
Output Voltages
OUT...................................................... –0.3V to 140V
Average Currents
VIN....................................................................–20mA
OUT....................................................................±5mA
REF.....................................................................±5mA
INH, INL..............................................................–1mA
Operating Ambient Temperature Range
LTC2965C................................................. 0°C to 70°C
LTC2965I..............................................–40°C to 85°C
LTC2965H........................................... –40°C to 125°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................... 300°C
PIN CONFIGURATION
TOP VIEW
VIN 1
REF 2
INH 3
9
GND
INL 4
TOP VIEW
8
OUT
7
GND
6
RS
5
PS
VIN
NC
NC
NC
NC
REF
INH
INL
OUT
NC
NC
NC
NC
GND
RS
PS
16
15
14
13
12
11
10
9
MS PACKAGE
16-LEAD PLASTIC MSOP
DD PACKAGE
8-LEAD (3mm × 3mm) PLASTIC DFN
TJMAX = 150°C, θJA = 120°C/W
TJMAX = 150°C, θJA = 43°C/W
EXPOSED PAD (PIN 9) PCB GND CONNECTION OPTIONAL
ORDER INFORMATION
1
2
3
4
5
6
7
8
(http://www.linear.com/product/LTC2965#orderinfo)
Lead Free Finish
TUBE
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC2965CDD#PBF
LTC2965CDD#TRPBF
LGMK
8-Lead (3mm × 3mm) Plastic DFN
0°C to 70°C
LTC2965IDD#PBF
LTC2965IDD#TRPBF
LGMK
8-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LTC2965HDD#PBF
LTC2965HDD#TRPBF
LGMK
8-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LTC2965CMS#PBF
LTC2965CMS#TRPBF
2965
16-Lead Plastic MSOP
0°C to 70°C
LTC2965IMS#PBF
LTC2965IMS#TRPBF
2965
16-Lead Plastic MSOP
–40°C to 85°C
LTC2965HMS#PBF
LTC2965HMS#TRPBF
2965
16-Lead Plastic MSOP
–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 nonstandard 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/. Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
2965fc
2
For more information www.linear.com/LTC2965
LTC2965
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 12V, RS = GND, PS = GND,
INH = 1.2V, INL = GND (Notes 1, 2).
SYMBOL
VIN
VMON
IVIN
VUVLO
PARAMETER
Input Supply Operating Range
VIN Monitor Range
VIN Input Supply Current
Undervoltage Lockout
Undervoltage Lockout Hysteresis
Comparator Reference Input: INH, INL
Comparator Common Mode Voltage
VCM
VIN Error Voltage at 96V
VERR
VIN Error Voltage at 24V
VOS
AVERR
VHYS
Comparator Offset Voltage
Internal Resistive Divider Range Error
Comparator Built-in Hysteresis
VHYTH
tPD
Built-in Hysteresis Enable Threshold
VIN to OUT Comparator Propagation Delay
IIN(LKG)
Input Leakage Current (INH, INL)
Reference: REF
Reference Output Voltage
VREF
Noise
Reference Output Noise
Control Inputs: RS, PS
Select Input Threshold
VTH
Input Leakage Current
ILKG
Status Outputs: OUT
Voltage Output Low
VOL
VOH
Voltage Output High
IOH
IO(LKG)
Output Current High
Leakage Current, Output High
CONDITIONS
VIN
l
VIN = 100V, 40x
VIN Rising
VIN Falling
l
MIN
3.5
3.5
3
TYP
7
l
MAX
100
98
15
3
UNITS
V
V
µA
V
mV
V
mV
mV
mV
mV
mV
%
mV
mV
mV
µs
nA
nA
70
Overdrive = 10%, OUT Falling,10x
INH = GND, INL = 1.2V
V = 1.2V, I-Grade
V = 1.2V, H-Grade
l
40
2.45
±1360
±400
±315
±75
±3
±0.4
30
–14
175
80
l
l
±0.1
±0.1
±1
±10
IREF ≤ 100µA, VIN ≥ 3.5V
100Hz to 100kHz
l
2.378
2.402
140
2.426
V
µVRMS
l
0.4
1.4
±100
V
nA
100
400
2.75
4
–5
±250
mV
mV
V
V
µA
nA
l
INH = VREF, 40x
0.35V ≤ INH ≤ 2.4V, 40x
INH = VREF, 10x
0.35V ≤ INH ≤ 2.4V, 10x
INH = 0.35V, 10x
INH = 2.4V, Range = 10x, 40x
INH = GND, INL Rising, VIN = 24V
INL = GND , INH Falling, VIN = 24V
±250
±250
±35
±35
±1.9
l
l
l
l
l
l
l
V = 2.4V
l
VIN = 1.25V, I = 10µA
VIN = 3.5V, I = 500µA
VIN = 3.5V, I = –1µA
VIN ≥ 4.5V, I = –1µA
V = GND, VIN = 3.5V
V = 100V, VIN = 6V
l
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.
0.35
l
l
l
l
l
l
14
–30
100
2
2.8
–15
22
–22
2.375
3
–7.5
Note 2: All currents into pins are positive; all voltages are referenced to
GND unless otherwise noted.
2965fc
For more information www.linear.com/LTC2965
3
LTC2965
TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs VIN
VREF vs Temperature
12
2.412
10
2.408
8
2.404
2.450
I = –10µA
VREF vs Load Current
VIN = 3.5V
6
2.400
–45°C
25°C
90°C
125°C
RANGE = 40x
OUT = LOW
IREF = 0µA
2
0
20
40
60
VIN (V)
100
80
2.375
–45°C
25°C
90°C
125°C
2.392
2.388
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
2965 G01
2.450
2.400
2.396
4
0
VREF (V)
VREF (V)
IVIN (µA)
2.425
2.350
0.4
0
1.2
1.6
0.8
LOAD CURRENT (mA)
2965 G02
VREF vs VIN
2965 G03
Comparator VOS vs Temperature
% Range Error vs Temperature
1500
0.4
25°C
2.0
VINH(L) = 1.2V
1000
2.400
2.375
2.350
2.7
0.2
500
VOS (µV)
RANGE ERROR, AVERR (%)
VREF (V)
2.425
0
0
–500
–0.2
1µA
100µA
1mA
3.0
3.5
3.2
VIN (V)
3.7
–0.4
–50 –25
4.0
0
25 50 75 100 125 150
TEMPERATURE (°C)
2965 G04
50
–45°C
25°C
90°C
125°C
0
0.1
1
10
% OVERDRIVE (%)
100
28
|BUILT-IN HYSTERESIS| VHYS (mV)
PROPAGATION DELAY, tPD (µs)
75
25
0
25 50 75 100 125 150
TEMPERATURE (°C)
2965 G06
Built-In Hysteresis
vs Temperature
VINL = 1.2V
VINH = GND
VIN = 12V
100
–1500
–50 –25
2965 G05
VIN Falling Propagation Delay
vs % Overdrive
125
–1000
10x
40x
VINH(L) = 1.2V
26
24
22
20
18
16
–50
2965 G10
0
50
100
TEMPERATURE (°C)
150
2965 G08
2965fc
4
For more information www.linear.com/LTC2965
LTC2965
TYPICAL PERFORMANCE CHARACTERISTICS
Voltage Output High vs Pull-Down
Current (OUT)
4
Voltage Output Low vs Pull-Up
Current (OUT)
1.50
VIN = 12V
Voltage Output High
vs Input Voltage
3.5
–45°C
25°C
90°C
125°C
1.25
3
3.2
1
0
–45°C
25°C
90°C
125°C
0
–6
–9
–3
PULL-DOWN CURRENT (µA)
–12
2.9
VOH (V)
VOL (V)
VOH (V)
1.00
2
0.75
2.6
0.50
2.3
0.25
2.0
0
I = –1µA
0
1
5
2
3
4
PULL-UP CURRENT (mA)
3
4
5
6
7
8
VIN (V)
2965 G10
2965 G09
1.7
2965 G11
PIN FUNCTIONS
Exposed Pad (DD8 Only): Exposed pad may be left floating
or connected to device ground.
GND: Device Ground.
INH: High Comparator Reference Input. Voltage on this
pin is multiplied by the configured range setting to set
the VIN high or rising threshold. Keep within valid voltage
range, VCM, or tie to GND to configure built-in hysteresis
where high threshold for VIN becomes INL + VHYS scaled
according to the RS pin configuration.
INL: Low Comparator Reference Input. Voltage on this pin
is multiplied by the configured range setting to set the VIN
low or falling threshold. Keep within valid voltage range,
VCM, or tie to GND to configure built-in hysteresis where
low threshold becomes INH – VHYS scaled according to
the RS pin configuration. Otherwise, INH-INL sets the
hysteresis of the comparator. Oscillation will occur if INL
> INH unless built-in hysteresis is enabled.
OUT: Comparator Output. OUT consists of a high voltage
active pull-down and a gated, resistive (500kΩ) pull-up
to an internally generated supply between 3.5V and 5V
depending on input supply voltage. Blocking circuitry at
the pin allows the pin to be resistively pulled up to voltages as high as 100V without back conducting onto the
internal supply of the part. Polarity with respect to the VIN
pin is configured using the polarity select pin, PS. OUT
pulls low when the part is in UVLO.
PS: Polarity Selection. Connect to REF or a voltage >VTH
to configure comparator output to be inverting with respect to VIN. Otherwise connect pin to GND to configure
comparator output to be noninverting with respect to VIN.
REF: Reference Output. VREF with respect to GND. Use a
maximum of 1nF to bypass unless damping resistor is used.
RS: Range Select Input. RS selects 10x or 40x range.
Connect to REF or GND to configure pin. (See Table 1)
VIN: Voltage Monitor and Supply Input. An internal high
value resistive divider is connected to the pin. If VIN falls
below the UVLO threshold minus hysteresis, the output
is pulled low. If VIN < 1.2V, the logic state of the outputs
cannot be guaranteed.
2965fc
For more information www.linear.com/LTC2965
5
LTC2965
BLOCK DIAGRAMS
REF
1X
VIN
VREF
INTERNAL
REGULATOR
GND
70M
VINT
+
–
VHYTH
INH
–+
+
VHYS
VHYS
VINT
–
+–
OUT
INL
VHYTH
500k
–
+
PS
10x/40x
RS
2965 BD
2965fc
6
For more information www.linear.com/LTC2965
LTC2965
OPERATION
A built-in buffered reference gives the monitor flexibility to operate independently from a high voltage supply
without the requirement of additional low voltage biasing.
The reference provides an accurate voltage from which
a resistive divider to ground configures the threshold
voltage for the internal comparator. In addition, the REF
pin can be used as a logic high voltage for the range and
polarity select pins.
The input voltage threshold at VIN is determined by the
voltage on the INH and INL pins which are scaled by the
internal resistive divider. The LTC2965 offers two range
settings to select from, 10x and 40x, using the RS pin.
Use Table 1 to determine the correct configuration for
a desired range setting. The polarity select pin, (PS),
configures the OUT pin to be inverting or noninverting
with respect to VIN allowing the part to be configured for
monitoring overvoltage and undervoltage conditions with
either polarity output.
Table 1.
VIN MONITOR RANGE
RANGE SELECTION
RS
3.5V to 24.5V
10x
L
14V to 98V
40x
H
The INH pin determines the high or rising edge threshold
for VIN. If the monitored voltage connected to VIN rises
to the scaled INH voltage then the OUT pin is pulled high
assuming PS is ground. Likewise, the INL pin determines
the low or falling edge threshold for VIN in each channel.
If VIN falls to the scaled INL voltage then the OUT pin is
pulled low assuming PS is ground. The amount of hysteresis referred to VIN is the difference in voltage between
INH and INL scaled according to the RS pin configuration. INH and INL have an allowable voltage range, VCM.
Figure 1 shows the allowable monitor voltage at VIN for
each range as a function of comparator reference input
voltage (INL/INH).
Typically, an external resistive divider biased from REF is
used to generate the INH and INL pin voltages. A built-in
hysteresis feature requiring only two resistors can be
enabled on either the VIN rising edge by grounding INH
or on the falling edge by grounding INL. For example, it
is appropriate to ground INH to activate rising edge hysteresis if an accurate falling voltage threshold is required
for undervoltage detection. Conversely, it is appropriate
to ground INL for falling edge built-in hysteresis if an accurate overvoltage threshold is required. Do not ground
both INH and INL. Oscillation occurs if VINL > VINH unless
INH built-in hysteresis is enabled.
The high voltage OUT pins have the capability to be pulled
up to a user defined voltage as high as 100V with an
external resistor. The LTC2965 also includes an internal
500k pull-up resistor to an internal voltage between 3.5V
and 5V depending on input voltage. (See VOH in Electrical
Characteristics).
If the VIN pin falls below the UVLO threshold then the OUT
pin is pulled low regardless of the PS pin state.
100
MONITOR THRESHOLD, VIN (V)
The LTC2965 is a micropower single channel voltage
monitor with a 100V maximum operating voltage. Its
channel is comprised of an internal high value resistive
divider and a comparator with a high voltage output. A
reference voltage is provided to allow the thresholds to be
set independently. This configuration has the advantage
of being able to monitor very high voltages with very little
current draw while threshold programming is done using
low value resistors at low voltages. Integration of a resistive divider for high voltage sensing makes the LTC2965
a compact and low power solution for generating voltage
status signals to a monitoring system.
40x
10x
10
1
0.5
1
1.5
2
2.5
COMPARATOR REFERENCE INPUT (INL, INH) (V)
2965 F01
Figure 1. Monitor Threshold
vs Comparator Reference Inputs
2965fc
For more information www.linear.com/LTC2965
7
LTC2965
APPLICATIONS INFORMATION
Threshold Configuration
The closest 1% value is 909kΩ. R2 can be determined from:
The LTC2965 channel monitors the voltage applied to the
VIN input. A comparator senses the VIN pin on one of its
inputs through the internal resistive divider. The other
input is connected to INH/INL that is in turn biased with
external resistive dividers off of the REF pin as shown in
Figure 2a and 2b. The VIN rising and falling thresholds
are determined by:
VIN(RISE) = RANGE • VINH
Where RANGE is the configured range of the internal
resistive divider. In order to set the threshold for the
LTC2965, choose an appropriate range setting for the
desired VIN voltage threshold such that the INH and INL
voltages are within the specified common mode range,
VCM. For example, if a falling threshold of 18V is desired
for monitoring a 24V power supply then a range greater
than 10x is allowed. However, to maximize the accuracy
of the VIN threshold the smallest acceptable range is used,
10x in this case. To implement 2V of hysteresis referred
to VIN this means:
VINH = 2V, VINL = 1.8V
With 10x range the VIN thresholds are:
VIN(RISE) = 20V, VIN(FALL) = 18V
One possible way to configure the thresholds is by using three resistors to set the voltages on INH and INL.
See Figure 2a. The solution for R1, R2 and R3 provides
three equations and three unknowns. Maximum resistor
size is governed by maximum input leakage current. The
maximum input leakage current below 85°C is 1nA. For
a maximum error of 1% due to both input currents, the
resistive divider current should be at least 100 times the
sum of the leakage currents, or 0.2µA.
If in this example, a leakage current error of 0.1% is desired
then the total divider resistance is 1.2MΩ which results in
a current of 2µA through this network. For RSUM = 1.2MΩ
RSUM =R1+R2+R3
=
( VINH •RSUM ) –R1
VREF
(2V •1.2MΩ) – 909kΩ = 90.2kΩ
2.402V
The closest 1% value is 90.9kΩ. R3 can be determined
from RSUM:
R3 = RSUM – R1 – R2 = 1.2MΩ – 909kΩ – 90.9kΩ
= 200.1kΩ
VIN(FALL) = RANGE • VINL
R1=
R2 =
The closest 1% value is 200kΩ. Plugging the standard
values back into the equations yields the design values
for the VINH and VINL voltages:
VINH = 2.002V, VINL = 1.819V
The corresponding threshold voltages are:
VIN(RISE) = 20.01V, VIN(FALL) = 18.19V
Another possible way to configure the thresholds is with
independent dividers using two resistors per threshold to
set the voltages on INH and INL. See Figure 2b. Care must
be taken such that the thresholds are not set too close to
each other, otherwise the mismatch of the resistors may
cause the voltage at INL to be greater than the voltage at
INH which may cause the comparator to oscillate.
As in the previous example, if RSUM = 1.2MΩ is chosen
and the target for VINL is 1.8V:
RSUM =R1+R2
R1=
( VINL •RSUM ) = (1.8V •1.2MΩ) = 899.5kΩ
VREF
2.402V
The closest 1% value is 909kΩ. R2 can be determined by:
R1
VINL
(909kΩ) = 304kΩ
= (2.402V – 1.8V ) •
1.8V
R2 = ( VREF – VINL ) •
( VINL •RSUM ) = (1.8V •1.2MΩ) = 899.5kΩ
VREF
2.402V
2965fc
8
For more information www.linear.com/LTC2965
LTC2965
APPLICATIONS INFORMATION
The closest 1% value is 301kΩ. Plugging the standard
values back into the equation for VINL yields the design
voltage for VINL:
(R1• VREF ) = (909kΩ • 2.402V ) =1.804V
VINL =
(R1+R2) (301kΩ+909kΩ)
At this point in the independent divider example only the
values required to set the voltage at INL have been found.
Repeat the process for the INH input by substituting the
above equations with VINH for VINL, R3 for R1, R4 for R2
and VINH = 2.0V.
VIN
REF
VIN
LTC2965
R3
INH
R1
R2
GND
VIN
LTC2965
R4
INH
PS
R2
INL
RS
REF
INL
R1
R3
VIN(FALL) = RANGE • INL
Figure 3b introduces built-in hysteresis on the falling edge
because INL is pulled to ground. Similarly, a two-resistor
network, R3 and R4, is used to set the voltage on INH using:
R4 VREF
=
–1
R3 VINH
Using built-in hysteresis the VIN thresholds are:
VIN(FALL) = RANGE • (INH – VHYS)
OUT
RS
PS
GND
2965 F02ab
Figure 2a. Three-Resistor
Threshold Configuration
VIN(RISE) = RANGE • (INL + VHYS)
VIN(RISE) = RANGE • INH
VIN
OUT
Using built-in hysteresis, the VINA thresholds are:
Figure 2b.Two-Resistor
Threshold Configuration
Consider VINH = 2V with built-in hysteresis activated on
the falling edge. For 10x range, 1.1% falling hysteresis is
obtained. If a larger percentage of hysteresis is desired then
VINH is alternatively set to 0.5V and the range is selected
to be 40x to obtain the same VIN threshold but with 4.4%
falling hysteresis. The amount of built-in hysteresis is
scaled according to Table 2. If more hysteresis is needed
then it is implemented in the external resistive divider as
described in the Threshold Configuration section.
VIN
Using Built-In Hysteresis
The LTC2965 has the capability of simplifying the threshold
configuration such that only two resistors are required.
The device pins can be configured to select a built-in hysteresis voltage, VHYS, which can be applied to either the
rising or falling threshold depending on whether the INH
or INL pin is grounded. Note that the hysteresis voltage
at each range setting remains at a fixed value. Figure 3
introduces examples of each configuration. For example,
if INH is biased from an external divider and the INL pin is
grounded, then hysteresis is enabled on the low or falling
threshold. The low threshold is then –VHYS relative to the
high threshold determined by INH. Figure 3a introduces
built-in hysteresis on the rising edge because INH is pulled
to ground. A two-resistor network, R1 and R2, is used to
set the voltage on INL using:
REF
R2
VIN
OUT
LTC2965
INH
INL
R1
VIN
REF
R4
OUT
LTC2965
INH
INL
RS
GND
VIN
R3
PS
RS
GND
PS
2965 F03ab
Figure 3a. Rising Edge
Built-In Hysteresis
Figure 3b. Falling Edge
Built-In Hysteresis
Table 2. Built-In Hysteresis Voltage vs Range
RANGE
VIN REFERRED BUILT-IN HYSTERESIS
10x
220mV
40x
880mV
R2 VREF
=
–1
R1
V
INL
2965fc
For more information www.linear.com/LTC2965
9
LTC2965
APPLICATIONS INFORMATION
Error Analysis
The actual VIN falling threshold has an error tolerance of
±216mV or ±1.2%.
VIN thresholds are subject to the following errors:
• REF Voltage Variation (∆VREF)
Improving Threshold Accuracy
• Comparator Offset (VOS)
The biggest threshold error terms are:
• Internal Divider Range Error (AVERR)
• External Resistive Divider Accuracy
• External Resistive Divider Error (AXERR)
• REF Voltage Variation
The effect these errors have on the VIN threshold is
expressed by:
Even using 1% tolerance resistors, external resistive divider
accuracy still accounts for as much as ±2% threshold error
while REF voltage variation accounts for ±1% threshold
error. In order to minimize these threshold error terms,
an external reference can be used to set the thresholds for
INH/INL as shown in Figure 4. An LT6656-2.048 has an
initial accuracy of 0.05% and provides bias via the 0.1%
resistive divider network for INH and INL. It is biased off
of the LTC2965 REF pin. The threshold error tolerance
is calculated using the method described in the Typical
Applications section with ∆VREF = ±1.024mV given the
initial accuracy of the LT6656 2.048V output and using
0.1% tolerance resistors for the external divider.
VINH(L)
VERR =RANGE • ±VOS ±∆VREF •
± VINH(L) • A XERR
VREF
±RANGE • A VERR • VINH(L)
A XERR = 2 •
TOLERANCE VINH(L)
• 1–
VREF
100
External divider error is determined by the percentage tolerance values of the resistors. If 1% tolerance resistors are
used in the external divider then there is a 2% worst-case
voltage error associated with it. The effects of comparator
offset and VREF voltage are uncorrelated with each other.
Therefore, a Root-Sum-Square can be applied to the error
voltage referred to VIN. Using the example from Threshold
Configuration and assuming 1% resistors implement the
external resistive divider, the falling VIN threshold of approximately 18V has an error tolerance of:
V
VERR(REF) = (RANGE) ±∆VREF • INL
VREF
1.8V
= (10) • ±24mV •
=±180mV
2.402V
V
VERR(EXT) = (RANGE) ±VINL • 2 • 0.01• 1– INL
VREF
= (10) • (±1.8V • 0.0005) =±9mV
VERR(VOS) = (RANGE) (±∆VOS ) = (10) • (±3mV ) =±30mV
VERR(RS) = (RANGE) (±A VERR ) (±VINL )
= (10) • (±0.004) • (1.8V ) =±72mV
= (10) • (±1.8V • 0.005) =±90mV
2
2
2
2
+ VERR(EXT)
+ VERR(VOS)
+ VERR(RS)
VERR = VERR(REF)
VERR(VOS) = (RANGE) (±∆VOS ) = (10) • (±3mV ) =±30mV
=
VERR(RS) = (RANGE) (±A VERR ) (±VINL )
2
2
2
2
2
2
=±216mV
10
2
The resulting VIN threshold error is reduced to ±0.44%
from ±1.2% in the previous error analysis example.
2
2
2
2
+ VERR(EXT)
+ VERR(VOS)
+ VERR(RS)
VERR = VERR(REF)
(±180mV ) + (±90mV ) + (±30mV ) + (±72mV )
2
(±9mV ) + (±9mV ) + (±30mV ) + (±72mV )
=±79mV
= (10) • (±0.004) • (1.8V ) =±72mV
=
V
VERR(REF) = (RANGE) ±∆VREF • INL
VREF
1.8V
= (10) • ±1.024mV •
=±9mV
2.048V
V
VERR(EXT) = (RANGE) ±VINL • 2 • 0.001• 1– INL
VREF
2965fc
For more information www.linear.com/LTC2965
LTC2965
APPLICATIONS INFORMATION
VIN
1µF
R3
47.5k
0.1%
R2
200k
0.1%
R1
1.8M
0.1%
LT6656-2.048
OUT
IN
GND
R4
10k
REF
VIN
LTC2965
INH
INL
GND
2965 F04
Figure 4. Reducing VIN Threshold Error
Output Configuration with Polarity Selection
The OUT pin may be used with a wide range of user-defined
voltages up to 100V with an external resistor. Select a
resistor compatible with desired output rise time and load
current specifications. When the status outputs are low,
power is dissipated in the pull-up resistors. An internal
pull-up is present if the OUT pins are left floating or if
low power consumption is required. The internal pull-up
resistor does not draw current if an external resistor pulls
OUT up to a voltage greater than VOH.
If PS is connected to ground, the comparator output is
noninverting. This means that OUT pulls low when VIN
falls below the scaled INL voltages. OUT is released after
VIN rises above the scaled INH voltage. Likewise, if PS is
connected up to REF or a voltage > VTH, the comparator
output is inverting. This means that OUT pulls low when
VIN rises above the scaled INH voltage and is released
when VIN falls below the scaled INL voltage.
If the VIN pin falls below the UVLO threshold minus
hysteresis, the output is pulled to ground. The output is
guaranteed to stay low for VIN ≥ 1.25V regardless of the
output logic configuration.
It is recommended that circuit board traces associated
with the OUT pin be located on a different layer than those
associated with the INH/INL and REF pins where possible
to avoid capacitive coupling.
Hot Swap Events
connected to the input resonant ringing can occur as a
result of series inductance. The peak voltage could rise
to 2x the input supply, but in practice can reach 2.5x if
a capacitor with a strong voltage coefficient is present.
Circuit board trace inductances of as little as 10nH can
produce significant ringing. Ringing beyond the absolute
maximum specification can be destructive to the part and
should be avoided whenever possible. One effective means
to eliminate ringing seen at the VIN pins and to protect the
part is to include a 1kΩ to 5kΩ resistance between the
monitored voltage and the VIN pin as shown in Figure 5.
This provides damping for the resonant circuit. If there is
a decoupling capacitor on the VIN pins the time constant
formed by the RC network should be considered.
VIN
RS
1k
VINA/VINB
LTC2965
GND
2965 F05
Figure 5. Hot Swap Protection
High Voltage Pin Creepage/Clearance Options
Appropriate spacing between component lead traces is
critical to avoid flashover between conductors. There
are multiple industry and safety standards that have
different spacing requirements depending on factors such
as operating voltage, presence of conformal coat, elevation,
etc. The LTC2965 is available in a 16-lead MSOP package
which offers landing clearance of at least 0.79mm (0.031in).
The package incorporates unconnected pins between all
adjacent high voltage and low voltage pins to maximize
PC board trace clearance. For voltages >30V the MSOP
should be used, otherwise the smaller or DFN is sufficient
when clearance is not an issue. For more information, refer
to the printed circuit board design standards described in
IPC2221 and UL60950.
The LTC2965 can withstand high voltage transients up
to 140V. However, when a supply voltage is abruptly
2965fc
For more information www.linear.com/LTC2965
11
LTC2965
APPLICATIONS INFORMATION
Voltage Reference
The REF pin is a buffered reference with a voltage of VREF
referenced to GND. A bypass capacitor up to 1000pF
in value can be driven by the REF pin directly. Larger
capacitances require a series resistance to dampen the
transient response as shown in Figure 6A. If a resistive
divider is already present then the bypass capacitor can
be connected to the INH or INL pin as shown in Figure 6B.
Figure 6C shows the resistor value required for different
capacitor values to achieve critical damping. Bypassing the
reference can help prevent false tripping of the comparators by preventing glitches on the INH/INL pins. Figure 7
shows the reference load transient response. Figure 8
shows the reference line transient response. If there is a
decoupling capacitor on the INH/INL pin the time constant
formed by the RC network should be considered. Use a
capacitor with a compatible voltage rating.
REF
CREF
INL
GND
INL
2965 F07
100µs/DIV
Figure 7. VREF Load Transient
1nF
1µF + 600Ω
VIN
1V/DIV
3.5V
6b
2965 F08
10µs/DIV
Figure 8. VREF Line Transient
100
RESISTANCE VALUE (kΩ)
VREF
GND
2965 F06ab
6a
LOAD CURRENT
10µA
8V
INH
CREF
100µA
VREF
LTC2965
RS
INH
2.4V
50mV/DIV
2.4V
10mV/DIV
REF
LTC2965
RS
1nF
10nF + 4.3kΩ
0.1µF + 1.5kΩ
1µF + 600Ω
10
1
0.1
0.001
0.01
0.1
CAPACITANCE VALUE (µF)
1
2965 F06c
6c
Figure 6. Using Series Resistance to Dampen REF
Transient Response
2965fc
12
For more information www.linear.com/LTC2965
LTC2965
TYPICAL APPLICATIONS
Negative Voltage Monitor with Output Level Shift
Current Sink/Source
Figure 9 illustrates an LTC2965 configured to monitor a
–15V supply with a level-shifted output to a 5V supply. Q1
buffers the digital input of the 5V system from the –15V
supply and prevents UV from going below GND. The
OUT pin drives the base of Q1 through a resistor network
comprised of R3 and R4. Keep R4/R3 ≥0.4 to ensure
there is proper base current to pull UV to ground. If an
exposed pad is present it should be tied to the LTC2965
GND pin or left open.
The LTC2965 can be used as a high voltage current source
or a current sink as shown in Figure 10. The current is
determined by placing a resistive load, RSET, on the REF
pin. The total current is then VREF/RSET + IVA because the
bias current of the part adds a small error term. Part of
the bias current is the internal resistive divider which is
approximately 78MΩ with the RS pin configured to 10x.
5V
–15V MONITOR WITH LEVEL SHIFT
RISING THRESHOLD
FALLING THRESHOLD
HYSTERESIS
RANGE SETTING
R4
510k
–14.5V
–14.2V
–0.3V
10X
R3
1M
LTC2965
INH
R2
976k
DIGITAL
INPUT
UV
Q1
MMBT2907
FAIRCHILD
VIN
REF
R5
200k
OUT
INL
R1
1.43M
PS
RS GND
–15V
2965 F09
Figure 9. Negative Voltage Monitor with Output Level Shift to a 5V Digital Input
Current Sink
ISET = VREF/RSET
Current Source
ISET = VREF/RSET
VIN
ISINK = 1mA
LOAD
VIN
VIN
VIN
REF
REF
LTC2965
LTC2965
RSET
2.4k
INH
OUT
OPEN
INL
PS
RS GND
RSET
2.4k
INH
OUT
OPEN
INL
PS
RS GND
IERROR = (VREF/RSET) – ISUPPLY
LOAD
ISRC = 1mA
2965 F10
Figure 10. LTC2965 Configured as High Voltage Current Source
2965fc
For more information www.linear.com/LTC2965
13
LTC2965
TYPICAL APPLICATIONS
Configure the current to be no greater than 1mA to ensure
that the REF voltage stays within ±1% tolerance. Current
values larger than 1mA exceed the REF buffer’s load
regulation capability and cause the REF voltage to drop
out of regulation.
Shunt Mode Hysteretic Regulator
Figure 11 shows the LTC2965 used as the controller for a
shunt mode hysteretic regulator to manage a battery-based
solar power system. When the battery voltage reaches a
lower float limit of 13.7V Q1 turns off and the solar panel
current passes through to the battery and load. Once
the battery voltage rises to the upper charging limit of
14.7V, Q1 turns on shorting the solar panel to ground
with D1 isolating the battery from the shunt path. The
upper and lower thresholds are generated from the onchip reference as a separate external divider to set INH
and INL and scaled by 10x. The charging thresholds are
temperature compensated by an NTC thermistor over a
0°C to 50°C range.
2965fc
14
For more information www.linear.com/LTC2965
LTC2965
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/product/LTC2965#packaging for the most recent package drawings.
DD Package
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698 Rev C)
0.70 ±0.05
3.5 ±0.05
1.65 ±0.05
2.10 ±0.05 (2 SIDES)
PACKAGE
OUTLINE
0.25 ±0.05
0.50
BSC
2.38 ±0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
PIN 1
TOP MARK
(NOTE 6)
0.200 REF
3.00 ±0.10
(4 SIDES)
R = 0.125
TYP
5
0.40 ±0.10
8
1.65 ±0.10
(2 SIDES)
0.75 ±0.05
4
0.25 ±0.05
1
(DD8) DFN 0509 REV C
0.50 BSC
2.38 ±0.10
0.00 – 0.05
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1)
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 TOP AND BOTTOM OF PACKAGE
2965fc
For more information www.linear.com/LTC2965
15
LTC2965
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/product/LTC2965#packaging for the most recent package drawings.
MS Package
16-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1669 Rev A)
0.889 ±0.127
(.035 ±.005)
5.10
(.201)
MIN
3.20 – 3.45
(.126 – .136)
4.039 ±0.102
(.159 ±.004)
(NOTE 3)
0.50
(.0197)
BSC
0.305 ±0.038
(.0120 ±.0015)
TYP
RECOMMENDED SOLDER PAD LAYOUT
0.254
(.010)
DETAIL “A”
3.00 ±0.102
(.118 ±.004)
(NOTE 4)
4.90 ±0.152
(.193 ±.006)
0° – 6° TYP
0.280 ±0.076
(.011 ±.003)
REF
16151413121110 9
GAUGE PLANE
0.53 ±0.152
(.021 ±.006)
DETAIL “A”
0.18
(.007)
SEATING
PLANE
1.10
(.043)
MAX
0.17 – 0.27
(.007 – .011)
TYP
1234567 8
0.50
(.0197)
BSC
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
0.86
(.034)
REF
0.1016 ±0.0508
(.004 ±.002)
MSOP (MS16) 0213 REV A
2965fc
16
For more information www.linear.com/LTC2965
LTC2965
REVISION HISTORY
REV
DATE
DESCRIPTION
A
09/15
Fixed typos
PAGE NUMBER
B
03/16
Added Absolute Maximum Rating for INH and INL Pins
2
C
08/17
Corrected example error threshold calculations
10
3, 4, 10 – 12
2965fc
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.
For more
information
www.linear.com/LTC2965
17
LTC2965
TYPICAL APPLICATION
D1
B130**
25V
100µF
1A
SOLAR
PANEL
FUSE
2A
1M
LC-P127R2P***
(12V, 7.2Ah)
VIN
REF
Q1
BUK7640-100A*
46.4k
LTC2965
OUT
INH
150k
6.81k
47nF
INL
95.3k
GND RS
*NXP
**DIODES INC
***PANASONIC
****MURATA NCP18WF104JO3RB
100mA MAXIMUM
24 HOUR AVERAGE
LOAD CURRENT
PS
NTC****
100k
2965 F11
Figure 11. Shunt Mode Hysteretic Regulator
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
LTC1440/LTC1441/ Ultralow Power Single/Dual Comparator with Reference
LTC1442
Adjustable Hysteresis, 3mm × 3mm × 0.75mm DFN Package
LTC1726/LTC1727/ Micropower Triple Supply Monitor
LTC1728
Adjustable Reset and Watchdog Timeouts
LTC1985
5-Lead SOT-23 Package
Micropower Triple Supply Monitor with Push-Pull Reset Output
LTC2900/LTC2901/ Programmable Quad Supply Monitor
LTC2902
Adjustable Reset, Watchdog Timer and Tolerance,
10-Lead MSOP and DFN Packages
LTC2903
Precision Quad Supply Monitor
6-Lead SOT-23 and DFN Packages
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/LTC2919
Precision Triple/Dual Input UV, OV and Negative Voltage Monitor
Shunt Regulated VCC Pin, Adjustable Threshold and Reset
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/ Single/Dual/Quad UV and OV Voltage Monitors
LTC2914
Separate VCC Pin, Adjustable Reset Timer
LTC2915/LTC2916
LTC2917/LTC2918
Single Voltage Supervisors with 27 Pin-Selectable Thresholds
Manual Reset and Watchdog Functions, 8- and 10-Lead
TSOT-23, MSOP and DFN Packages
LTC2966
100V Micropower Dual Voltage Monitor
1.75V to 98V Monitoring Range, 3.5V to 100V Operating Range,
7µA Quiescent Current
LTC2960
36V Nano-Current Two Input Voltage Monitor
36V, 850nA Quiescent Current, 2mm × 2mm 8-Lead DFN and
TSOT-23 Packages
LT6700
Micropower Dual Comparator with 400mV Reference
SOT-23, 2mm × 3mm DFN Package
2965fc
18
LT 0817 REV C • PRINTED IN USA
For more information www.linear.com/LTC2965
www.linear.com/LTC2965
LINEAR TECHNOLOGY CORPORATION 2015
工商网监
湘ICP备2023018690号
