LINER LTC1696 Overvoltage protection controller Datasheet

LTC1696
Overvoltage Protection
Controller
FEATURES
DESCRIPTION
±2% Overvoltage Threshold Accuracy
nn Low Profile (1mm) ThinSOT™ Package
nn Gate Drive for SCR Crowbar or External N-Channel
Disconnect MOSFET
nn Monitors Two Output Voltages
nn Senses Output Voltages from 0.8V to 24V
nn Wide Supply Range: 2.7V to 27V
nn Multifunction TIMER/RESET Pin
The LTC®1696 is a standalone power supply overvoltage monitor and protection device designed to protect a
power supply load in the event of an overvoltage fault. It
monitors two adjustable output voltages. If an overvoltage
condition is detected, the output drives either an external
SCR crowbar or turns off external back-to-back N-channel
MOSFETs, thereby, disconnecting the input voltage from
the power supply.
nn
Pin 6 offers three functions. By connecting a capacitor
to this pin, the internal glitch filter time delay can be
programmed. Without the capacitor, the default time
delay is determined by an internal capacitor. This pin also
serves as a reset input to clear the internal latch after an
overvoltage fault condition. By pulling it high, the OUT
pin is activated if the FB1 and FB2 voltages remain below
the trip threshold.
APPLICATIONS
Telecommunication Systems
Computer Systems
nn Industrial Control Systems
nn Notebook Computers
nn
nn
The LTC1696 is available in the low profile (1mm)
ThinSOT package.
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
SCR Crowbar
Overvoltage Response
VOUT2
5V
VOUT1
3.3V
POWER
SUPPLY
VCC
12V
R2
137k
1%
R1
44.2k
1%
1
LTC1696
2
3
SCR
2N6507
TIMER/ 6
RESET
FB1
C2
0.1µF
GND
VCC
FB2
OUT
FB1
0.5V/DIV
R4
232k
1%
C1
1nF
Q1
2N7002
TIMER/RESET
2V/DIV
RESET
5
IOUT
20mA/DIV
R3
44.2k
1%
4
C1 = 1nF
100µs/DIV
1696 TA02
1696 TA01
1696fb
For more information www.linear.com/LTC1696
1
LTC1696
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
Supply Voltage (VCC).................................................28V
Input Voltage
FB1, FB2................................................ – 0.3V to 17V
TIMER/RESET......................................... –0.3V to 17V
Operating Junction Temperature Range (Note 2)
LTC1696E............................................ –40°C to 125°C
LTC1696I............................................ –40°C to 125°C
LTC1696H........................................... –40°C to 150°C
Storage Temperature Range.................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
TOP VIEW
TIMER/
RESET
5 FB2
FB1 1
6
GND 2
VCC 3
4 OUT
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
TJMAX = 150°C, θJA = 192°C/W
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC1696ES6#PBF
LTC1696ES6#TRPBF
LTLT
6-Lead Plastic TSOT-23
–40°C to 125°C
LTC1696IS6#PBF
LTC1696IS6#TRPBF
LTLT
6-Lead Plastic TSOT-23
–40°C to 125°C
LTC1696HS6#PBF
LTC1696HS6#TRPBF
LTLT
6-Lead Plastic TSOT-23
–40°C to 150°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/
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at TA = 25°C. 2.7V ≤ VCC ≤ 27V (Notes 2, 3, 4) unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
UNITS
Supply Voltage Range
Operating Range
●
IVCC
Standby Supply Current
FB1, FB2 < VFB
●
Active Supply Current
FB1, FB2 > VFB, COUT = 1000pF
●
VFB
FB1, FB2 Feedback Threshold
Voltage Going Positive TA ≥ 0°C and TA ≤ 85°C
TA ≥ 0°C and TA ≤ 125°C
TA ≥ 0°C and TA ≤ 150°C
TA < 0°C
●
●
●
●
0.862
0.858
0.853
0.853
IFB
FB1, FB2 Input Current
●
–1
– 0.05
µA
VFBHST
FB1, FB2 Feedback Hysteresis
High-to-Low Transition
12
mV
VLKO
VCC Undervoltage Lockout
Low-to-High Transition
High-to-Low Transition
FB1, FB2 > VFB
VLKH
VCC Undervoltage Lockout Hysteresis
FB1, FB2 > VFB
VRST
TIMER/RESET Reset Low Threshold
FB1, FB2 > VFB
VTIM
TIMER/RESET Timer High Threshold
FB1, FB2 > VFB,
2
●
●
2.7
MAX
VCC
27
V
540
µA
1.1
3.5
mA
0.880
0.880
0.880
0.880
0.898
0.898
0.898
0.907
170
1.75
1.64
2.05
1.94
2.35
2.24
110
TA ≤ 85°C
TA ≤ 125°C
TA ≤ 150°C
V
V
V
V
V
V
mV
●
0.78
0.865
0.95
V
●
●
●
1.11
1.08
1.07
1.185
1.185
1.185
1.26
1.26
1.26
V
V
V
1696fb
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LTC1696
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at TA = 25°C. 2.7V ≤ VCC ≤27V (Notes 2, 3, 4) unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
1.35
1.50
1.65
V
260
650
µA
VTRIG
TIMER/RESET External Trigger High
Threshold
FB1, FB2 < VFB
●
ITRIG
TIMER/RESET External Trigger High
Current
FB1, FB2 < VFB, TIMER/RESET = VTRIG
●
ITIM
TIMER/RESET Timer Current
FB1 = (VFB + 30mV), FB2 < VFB
FB1 = (VFB + 200mV), FB2 < VFB
FB2 = (VFB + 30mV), FB1 < VFB
FB2 = (VFB + 200mV), FB1 < VFB
FB1, FB2 = (VFB + 200mV)
●
●
●
●
●
4
5
4
5
8
10
12
10
12
18
22
26
22
26
40
µA
µA
µA
µA
µA
VOUTH
OUT High Voltage
12V ≤ VCC ≤ 27V, FB1, FB2 > VFB, COUT = 1000pF
VCC = 3.3V, FB1, FB2 > VFB, COUT = 1000pF
●
●
4.8
2.7
6.3
3.2
8.0
3.3
V
V
VOUTL
OUT Low Voltage
FB1, FB2 < VFB, ISINK = 1mA, VCC = 3.3V
●
0.45
V
tOVPD1
OUT Propagation Delay for FB1
FB1 > VFB, FB2 < VFB, TIMER/RESET = Open,
COUT = 1000pF
●
7
28
µs
tOVPD2
OUT Propagation Delay for FB2
FB2 > VFB, FB1 < VFB, TIMER/RESET = Open,
COUT = 1000pF
●
7
28
µs
tOVPD1,2
OUT Propagation Delay for FB1, FB2
FB1, FB2 > VFB, TIMER/RESET = Open
COUT = 1000pF
●
6
24
µs
tr
OUT Rise Time
FB1, FB2 > VFB, COUT = 1000pF
●
0.4
3
µs
IOUTSC
OUT Short-Circuit Current
12V ≤ VCC ≤ 27V, FB1, FB2 > VFB,
VOUT Shorted to GND
●
35
80
160
mA
VCC = 2.7V, FB1, FB2 > VFB, VOUT Shorted to GND
●
2
9
18
mA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: The 1696E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the -40°C to 125°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC1696I is guaranteed
from -40°C to 125°C, and the LTC1696H is guaranteed over the -40°C to
150°C operating junction temperature range. High junction temperatures
degrade operating lifetime; operating lifetime is derated for temperatures
greater than 125°C. The maximum ambient temperature consistent with
these specifications is determined by specific operating conditions in
conjunction with board layout, the package thermal impedance and other
environmental factors. TJ is calculated from the ambient temperature, TA ,
and power dissipation, PD , according to the following formula:
LTC1696S6: TJ = TA + (PD • 192°C/W)
Note 3: All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to device ground unless
otherwise specified.
Note 4: All typical numbers are given for VCC = 12V and TA = 25°C.
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LTC1696
TYPICAL PERFORMANCE CHARACTERISTICS
Standby Supply Current
vs Supply Voltage
210
TA = 25°C
180
200
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
160
140
120
100
80
60
180
170
160
150
140
20
130
0
5
15
20
10
SUPPLY VOLTAGE (V)
25
0
1.1
1.05
1
25 50 75 100 125 150
TEMPERATURE (°C)
0.8814
0.8811
0.8808
0.8805
0.8802
0.8799
0.8796
0
3
6
9 12 15 18 21 24 27 30
SUPPLY VOLTAGE (V)
1.185
1.180
1.175
1.170
1.165
1.160
0
5
10
20
15
SUPPLY VOLTAGE (V)
25
30
1696 G07
4
0.9
VCC = 12V
0.89
0.88
0.87
0.86
0.85
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
1696 G06
TIMER Current vs Supply Voltage
20
VCC = 12V
1.2
1.18
1.16
1.14
–50 –25
TA = 25°C
18
1.22
TIMER CURRENT (µA)
TA = 25°C
TIMER THRESHOLD VOLTAGE (V)
TIMER THRESHOLD VOLTAGE (V)
1.24
30
25
1696 G03
TIMER Threshold Voltage
vs Temperature
1.190
20
15
10
SUPPLY VOLTAGE (V)
5
1696 G05
TIMER Threshold Voltage
vs Supply Voltage
1.195
0
FB1, FB2 Feedback Threshold
Voltage vs Temperature
TA = 25°C
1696 G04
1.200
0.4
0
FB1/FB2 FEEDBACK THRESHOLD VOLTAGE (V)
FB1, FB2 FEEDBACK THRESHOLD VOLTAGE (V)
SUPPLY CURRENT (mA)
1.15
0
0.6
FB1, FB2 Feedback Threshold
Voltage vs Supply Voltage
VCC = 12V
COUT = 1000pF
0.95
–50 –25
0.8
1696 G02
Active Supply Current
vs Temperature
1.2
1.0
25 50 75 100 125 150
TEMPERATURE (°C)
1696 G01
1.25
TA = 25°C
COUT = 1000pF
0.2
120
–50 –25
30
Active Supply Current
vs Supply Voltage
1.2
190
40
0
1.4
VCC = 12V
SUPPLY CURRENT (mA)
200
Standby Supply Current
vs Temperature
FB1 AND FB2 OVERDRIVE = 200mV
16
14
FB1 OR FB2 OVERDRIVE = 200mV
12
10
0
25 50 75 100 125 150
TEMPERATURE (°C)
1696 G08
8
0
5
10
15
20
SUPPLY VOLTAGE (V)
25
30
1696 G09
1696fb
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LTC1696
TYPICAL PERFORMANCE CHARACTERISTICS
TIMER Current
vs Feedback Overdrive
22
20
VCC = 12V
18
FB1 + FB2 OVERDRIVE 200mV
16
FB1 AND FB2 OVERDRIVE
FB1 OR FB2 OVERDRIVE 200mV
12
FB1 OR FB2 OVERDRIVE
12
8
4
10
8
–50 –25
0
0
25 50 75 100 125 150
TEMPERATURE (°C)
0
50
150
200
100
FEEDBACK OVERDRIVE (mV)
FB1 OR FB2 OVERDRIVE
FB1 AND FB2 OVERDRIVE
5
50
150
200
100
FEEDBACK OVERDRIVE (mV)
0
20
15
10
FB1 OR FB2 OVERDRIVE
5
FB1 AND FB2 OVERDRIVE
0
250
0
50
100
150
200
FEEDBACK OVERDRIVE (mV)
1.49
1.485
1.48
1.475
–50 –25
0
250
1.51
25 50 75 100 125 150
TEMPERATURE (°C)
1696 G16
TA = 25°C
1.50
1.49
1.48
1.47
1.46
1.45
1.44
0
20
15
10
SUPPLY VOLTAGE (V)
5
30
RESET Threshold Voltage
vs Temperature
0.88
TA = 25°C
0.866
0.875
0.864
0.87
0.862
0.860
0.858
0.856
0.854
0.852
25
1696 G15
RESET THRESHOLD (V)
RESET THRESHOLD VOLTAGE (V)
EXTERNAL TRIGGER THRESHOLD VOLTAGE (V)
0.868
VCC = 12V
250
1696 G12
RESET Threshold Voltage
vs Supply Voltage
1.495
50
100
150
200
FEEDBACK OVERDRIVE (mV)
1696 G14
External Trigger Threshold
Voltage vs Temperature
1.5
0
External Trigger Threshold
Voltage vs Supply Voltage
1696 G13
1.505
8
4
250
VCC = 12V
TA = 25°C
25
GLITCH FILTER TIMER (µs)
GLITCH FILTER TIMER (µs)
30
VCC = 3.3V
TA = 25°C
10
FB1 OR FB2 OVERDRIVE
10
Glitch Filter Timer
vs Feedback Overdrive
15
0
12
1696 G11
Glitch Filter Timer
vs Feedback Overdrive
20
FB1 AND FB2 OVERDRIVE
6
1696 G10
25
VCC = 3.3V
TA = 25°C
14
EXTERNAL TRIGGER TRESHOLD VOLTAGE (V)
14
16
VCC = 12V
TA = 25°C
16
TIMER CURRENT (µA)
TIMER CURRENT (µA)
20
TIMER Current
vs Feedback Overdrive
TIMER CURRENT (µA)
TIMER Current vs Temperature
VCC = 12V
0.865
0.86
0.855
0.85
0.845
0
5
10
20
15
SUPPLY VOLTAGE (V)
25
30
1696 G17
0.84
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
1696 G18
1696fb
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5
LTC1696
TYPICAL PERFORMANCE CHARACTERISTICS
OUT Pin Active Output Voltage
vs Supply Voltage
6.6
6
5
4
3
2
1
0
0
5
10
20
15
SUPPLY VOLTAGE (V)
25
6.5
6.4
6.3
6.2
6.1
6
5.9
5.8
5.7
–50 –25
30
0
80
VCC = 12V
60
8
–50 –25
VCC = 5V
VCC = 2.7V
0
50
40
30
20
TA = 25°C
VOUT SHORTED TO GND
10
0
5
15
20
10
SUPPLY VOLTAGE (V)
30
25
1696 G21
OUT Pin Active Output Current
vs Output Voltage
100
TA = 25°C
TA = 25°C
90
25
20
VCC = 5V
15
10
VCC = 2.7V
5
80
70
60
50
VCC = 27V
40
30
VCC = 12V
20
10
25 50 75 100 125 150
TEMPERATURE (°C)
1696 G10
6
30
ACTIVE OUTPUT CURRENT (mA)
OUT PIN SHORT-CIRCUIT CURRENT (mA)
VCC = 27V
20
70
60
OUT Pin Active Output Current
vs Output Voltage
VOUT SHORTED TO GND
40
80
1696 G20
OUT Pin Short-Circuit Current
vs Temperature
100
90
0
25 50 75 100 125 150
TEMPERATURE (°C)
1696 G19
120
100
VCC = 12V
COUT = 1000pF
ACTIVE OUTPUT CURRENT (mA)
7
OUT Pin Short-Circuit Current
vs Supply Voltage
OUT PIN SHORT-CIRCUIT CURRENT (mA)
TA = 25°C
COUT = 1000pF
OUT PIN ACTIVE OUTPUT VOLTAGE (V)
OUT PIN ACTIVE OUTPUT VOLTAGE (V)
8
OUT Pin Active Output Voltage
vs Temperature
0
0 0.5 1
1.5 2 2.5 3 3.5 4
OUTPUT VOLTAGE (V)
4.5
5
1696 G23
0
0
1
4
3
2
5
OUTPUT VOLTAGE (V)
6
7
1696 G24
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LTC1696
PIN FUNCTIONS
FB1 (Pin 1): First Feedback Input. FB1 monitors and senses
the first supply output voltage through an external resistor
divider. This voltage is then compared with an internal
reference voltage of 0.88V, which sets the threshold for
an overvoltage fault detection. If the sense voltage exceeds
the threshold level, the output response time at the OUT
pin is dependent on the feedback overdrive above the
threshold level. The higher the feedback overdrive, the
faster will be the response time.
FB2 (Pin 5): S
econd Feedback Input. FB2 monitors and
senses the second supply output voltage through an
external resistor divider. This voltage is then compared
with an internal reference voltage of 0.88V, which sets the
threshold for an overvoltage fault detection. If the sense
voltage exceeds the threshold level, the output response
time at the OUT pin is dependent on the feedback overdrive above the threshold level. The higher the feedback
overdrive, the faster will be the response time.
GND (Pin 2): Power Ground. Return path for all device
currents.
TIMER/RESET (Pin 6): Glitch Filter Timer Capacitor,
Reset and External Trigger Input. The external capacitor
connected to this pin programs the internal glitch filter
time delay. The internal current source used to charge the
timer capacitor is typically 10µA with feedback overdrive
of less than 20mV above the feedback trip threshold from
one feedback input. The current source increases to 12µA
when the feedback overdrive increases to more than
100mV. It further increases to 18µA if larger overdrive
occurs from both feedback inputs. The default glitch filter
time delay without an external timer capacitor is fixed by
an internal capacitor of 5pF with the internal reference
voltage of 1.185V. The delay reduces with increases in
first and second feedback input overdrive. This pin also
serves as a reset input to clear the internal latch during
an overvoltage fault condition. If pulled low, it resets the
active high state of the internal latch. The reset signal to
this pin should be an open drain type. This pin can also be
driven high externally to activate the OUT pin active high
if the FB1 and FB2 voltages remain below the feedback
trip threshold.
VCC (Pin 3): Power Supply. The pin is connected separately
from the power supply output that the chip is monitoring.
Its input range is from 2.7V to 27V. The quiescent current
is typically 100µA in standby mode when the device is
operating at 5V. The quiescent current increases to 170µA
when operating at 12V.
OUT (Pin 4): Output Current Limit Driver. Capable of delivering continuous current, typically 80mA, at high supplies.
The output current decreases with lower supply voltage.
This pin directly drives the SCR crowbar at high supply
voltage. It can also provide gate drive for an N‑channel
MOSFET or the base of an NPN transistor, which drives
the gate of an external SCR at low supply voltage. It is
normally in the inactive low state in the standby mode. In
the event of an overvoltage fault condition, the OUT pin is
latched into the active high state. The latched active high
state is reset by pulling the TIMER/RESET pin low through
an N-channel MOSFET switch or if the supply voltage at
the VCC pin goes below the undervoltage lockout threshold
voltage of 1.94V.
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7
LTC1696
BLOCK DIAGRAM
VCC 3
R4
R3
INTERNAL 5V SUPPLY
R2
+
+
–
VREF
4 OUT
–
R1
2V
UVLO
–
GND 2
1.185V
INTERNAL 5V SUPPLY
FB2 5
+
–
BANDGAP
REFERENCE
0.88V
10µA +
FUNCTION
OF FB1 AND FB2
OVERDRIVE
+
+
+
–
FB1 1
GLITCH
FILTER
LOGIC
+
–
6
TIMER/
RESET
0.865V
1696 BD
8
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LTC1696
APPLICATIONS INFORMATION
Feedback Inputs
VS
The LTC1696 has two feedback inputs that allow monitoring of two output voltages. The trip point of the internal
comparator is set by an internal reference of 0.88V with
± 2% accuracy. The output voltage, VS, is sensed through
an external resistor divider network (Figure 1). The resistors R1 and R2 values are calculated with the typical trip
point of 0.88V.
R1
• V = 0.88
R1+ R2 S
As an example, let’s calculate values for R1 and R2 for a
3.3V supply in which an overvoltage indication is required
at +10% (3.63V). First, a value for R1 is chosen based on
the allowable resistor divider string current. This is determined by power dissipation requirements and possible
sensitivity to noise coupling into the resistor divider. In
this exercise, assume the resistor divider current is 20µA.
R1 is calculated from:
VFB
IDIVIDER
=
LTC1696
FB1
+
R1
–
+
–
VREF = 0.88V
Figure 1
(V − 0.88) • R1
R2 = S
0.88
R1=
R2
0.88V
= 44k
20µA
The chosen values for R1 and R2 yield an overvoltage
threshold of 3.608V (+ 9.3%). With worst-case tolerances
applied, the minimum overvoltage threshold is 3.481V
(+5.5%) and the maximum overvoltage threshold is
3.738V (+13.3%).
Reset Function
In the event of an overvoltage condition, the OUT pin of
the LTC1696 is latched into an active high state. The internal latch is reset by pulling the TIMER/RESET pin low
through an external N-channel MOSFET switch or pulling
VCC voltage below the UVLO trip point of 1.94V.
The nearest 1% value for R1 is 44.2k. Now, calculating
for R2 yields:
44.2k • (3.63v − 0.88V)
R2 =
= 138.1k
0.88V
Choosing the nearest 1% value yields 137k.
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9
LTC1696
APPLICATIONS INFORMATION
Glitch Filter Timer
SCR Crowbar
The LTC1696 has a programmable glitch filter to prevent
the output from entering its active high latched condition
if transients occur on the FB1 or FB2 pins. The filter time
delay is programmed externally by an external capacitor
C1 connected to the TIMER/RESET pin.
The LTC1696 can deliver continuous output current typically 80mA at high supply voltage to trigger an external
SCR crowbar in the event of an overvoltage condition as
shown in the typical application on the front page of the
data sheet. The output current decreases when the supply
voltage reduces. It delivers 25mA at a supply voltage of
5V. At a low supply voltage of 3.3V, the output current
reduces to 10mA and an external NPN emitter follower
is needed to boost the current in order to drive the SCR
crowbar as shown in Figure 2. The power dissipation
due to the high output current at high supply voltage can
potentially exceed the thermal limit of the package. This is
avoided by resetting the device rapidly when the external
SCR crowbar has been triggered, so that the device is not
kept in the active high state for too long.
The time delay is given by: tD =
C1• VINT
ICHG
where VINT is the internal reference voltage of 1.185V and
ICHG is the internal current source charging the external
capacitor C1. The current source ICHG charging the external
timer capacitor is 10µA for small feedback transients and
increases to 12µA for large feedback transients (greater
than 100mV) from one feedback input. The charging
current increases to 18µA for large feedback transients
from both feedback inputs.
R2
54.9k
1%
1
R1
44.2k
1%
Q1
2N3904
R5
470Ω
5%
VOUT2
2.5V
VOUT1
1.8 V
POWER
SUPPLY
VCC
3.3V
R6
22Ω
5%
TIMER/ 6
RESET
FB1
LTC1696
2
GND
FB2
VCC
OUT
R4
93.1k
1%
C1
1nF
3
RESET
5
R3
44.2k
1%
SCR
2N6507
C2
0.1µF
Q2
2N7002
4
1696 F02
Figure 2. External SCR with NPN Emitter Follower with Low Voltage Supplies
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For more information www.linear.com/LTC1696
LTC1696
APPLICATIONS INFORMATION
Back-to-Back N-Channel MOSFET
by the power management controller when the LTC1696
OUT pin is in the low state. The LTC1696 drives the gate
of Q1 high during an overvoltage fault condition. This
pulls the drain of Q1 low and turns off the back-to-back
N-channel MOSFETs.
A power management circuit that uses the LTC1696 to
control ­external back-to-back N-channel MOSFET at low
supply voltage is shown in Figure 3. In standby mode, the
drain of the external N-channel MOSFET, Q1, is pulled high
1.5V
R2
38.3k
1%
1
R1
44.2k
1%
VCC
3.3V
TIMER/ 6
RESET
FB1
LTC1696
2
3
C2
0.1µF
GND
FB2
VCC
OUT
C1
1nF
Q2
2N7002
5
4
R3
R4
44.2k 54.9k
1%
1%
RESET
1.8V
PRIMARY
INPUT
SUPPLY
POWER MANAGEMENT
CONTOLLER
N-CHANNEL
×2
Q1
2N7002
1696 F03
Figure 3. Back-to-Back N-Channel MOSFETs for Low Supply Application
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For more information www.linear.com/LTC1696
11
LTC1696
PACKAGE DESCRIPTION
S6 Package
6-Lead Plastic SOT-23
(LTC DWG # 05-08-1634)
(LTC DWG # 05-08-1636)
2.80 – 3.10
(.110 – .118)
(NOTE 3)
SOT-23
(Original)
SOT-23
(ThinSOT)
A
.90 – 1.45
(.035 – .057)
1.00 MAX
(.039 MAX)
A1
.00 – 0.15
(.00 – .006)
.01 – .10
(.0004 – .004)
A2
.90 – 1.30
(.035 – .051)
.80 – .90
(.031 – .035)
L
.35 – .55
(.014 – .021)
.30 – .50 REF
(.012 – .019 REF)
2.60 – 3.00
(.102 – .118)
1.50 – 1.75
(.059 – .069)
(NOTE 3)
PIN ONE ID
.95
(.037)
REF
.20
(.008)
A
DATUM ‘A’
L
NOTE:
1. CONTROLLING DIMENSION: MILLIMETERS
MILLIMETERS
2. DIMENSIONS ARE IN
(INCHES)
.25 – .50
(.010 – .020)
(6PLCS, NOTE 2)
A2
.09 – .20
(.004 – .008)
(NOTE 2)
1.90
(.074)
REF
A1
S6 SOT-23 0401
3. DRAWING NOT TO SCALE
4. DIMENSIONS ARE INCLUSIVE OF PLATING
5. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
6. MOLD FLASH SHALL NOT EXCEED .254mm
7. PACKAGE EIAJ REFERENCE IS:
SC-74A (EIAJ) FOR ORIGINAL
JEDEC MO-193 FOR THIN
12
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For more information www.linear.com/LTC1696
LTC1696
REVISION HISTORY
REV
DATE
DESCRIPTION
A
06/14
Added "I” and "H” Grade
B
12/14
Changed Equation
from
PAGE NUMBER
R1
• V = 0.88
R1+ R1 S
2–6
to
R1
• V = 0.88
R1+ R2 S
Changed Figure 2 schematic from Q1 to Q2
9
10
1696fb
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 representaof its circuits
as described
herein will not infringe on existing patent rights.
tion that the interconnection
For more
information
www.linear.com/LTC1696
13
LTC1696
TYPICAL APPLICATION
External Triggering
FB1 and FB2 pins are below the trip threshold of the internal comparator. The output is then reset by pulling the
TIMER/RESET pin low. Figure 4 shows a circuit that uses
the external triggering function of the LTC1696
The LTC1696 has a feature which allows the output to
be latched into an active high state by pulling the TIMER/
RESET pin high even if both the feedback voltages at the
5V
R5
6.8k
5%
D1
1N4148
1.5V
R2
38.3k
1%
1
R1
44.2k
1%
VCC
3.3V
C1
1nF
TIMER/ 6
RESET
FB1
LTC1696
2
3
C2
0.1µF
GND
FB2
VCC
OUT
5
Q2
2N7002
R4
54.9k
1%
R3
44.2k
1%
4
RESET
Q3
2N7002
TRIGGER
1.8V
PRIMARY
INPUT
SUPPLY
POWER MANAGEMENT
CONTOLLER
N-CHANNEL
×2
Q1
2N7002
1696 F04
Figure 4. External Triggering
RELATED PARTS
PART NUMBER DESCRIPTION
COMMENTS
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LTC3855
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LTC3875
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0.6V ≤ VOUT ≤ 5V, 4mm x 4mm QFN-24, TSSOP-24E
Value DCR Sensing and Temperature Compensation
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LTC3866
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Forward No Opto Synchronous Controller Chip Set
with Active Clamp Reset
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Adaptive or Manual Delay Control for Zero Voltage Switching,
Adjustable Synchronous Rectification Timing
14 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
For more information www.linear.com/LTC1696
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com/LTC1696
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LT 1214 REV B • PRINTED IN USA
 LINEAR TECHNOLOGY CORPORATION 2001