LTC2912
Single UV/OV
Voltage Monitor
FEATURES
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DESCRIPTION
The LTC
®
2912 voltage monitor is designed to detect power
supply undervoltage and overvoltage events. The VL and
VH monitor inputs include filtering to reject brief glitches,
thereby ensuring reliable reset operation without false or
noisy triggering. An adjustable timer defines the duration of
the overvoltage and undervoltage reset outputs which func-
tion independently. While the LTC2912 operates directly
from 2.3V to 6V supplies, an internal V
CC
shunt regulator
coupled with low supply current demand allows operation
from higher voltages such as 12V, 24V or 48V.
Three output configurations are available: the LTC2912-
1 has a latch control for the
OV
output; the LTC2912-2
has an
OV
and
UV
output disable feature for margining
applications; the LTC2912-3 is identical to the LTC2912-1
but with a noninverting,
OV
output.
The LTC2912 provides a precise, versatile, space-conscious
micropower solution for voltage monitoring.
, 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.
Monitors Single Voltage
Adjustable UV and OV Trip Values
Guaranteed Threshold Accuracy: ±1.5%
Power Supply Glitch Immunity
Adjustable Reset Timeout with Timeout Disable
29μA Quiescent Current
Open-Drain
OV
and
UV
Outputs
Guaranteed
OV
and
UV
for V
CC
≥ 1V
Available in 8-Lead ThinSOT
TM
and (3mm × 2mm)
DFN Packages
APPLICATIONS
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Desktop and Notebook Computers
Network Servers
Core, I/O Voltage Monitors
TYPICAL APPLICATION
Single OV/UV Supply Monitor, 3.3V ±10% Tolerance
POWER
SUPPLY
3.3V
0.1μF
UV/OV TIMEOUT PERIOD, t
UOTO
(ms)
Reset Time-Out Period vs Capacitance
10000
1000
27.4k
VH
1k
VL
4.53k
GND
V
CC
LTC2912-1
OV
UV
SYSTEM
100
10
LATCH
TMR
22nF
2912 TA01a
TIMEOUT = 200ms
1
0.1
1
10
100
TMR PIN CAPACITANCE, C
TMR
(nF)
1000
2912 G08
2912fa
1
LTC2912
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Terminal Voltages
V
CC
(Note 3)............................................. –0.3V to 6V
OV, UV, OV
............................................ –0.3V to 16V
TMR ..........................................–0.3V to (V
CC
+ 0.3V)
VH, VL,
LATCH,
DIS .............................. –0.3V to 7.5V
Terminal Currents
I
VCC
....................................................................10mA
I
UV
, I
OV
, I
OV
........................................................10mA
Operating Temperature Range
LTC2912C ................................................ 0°C to 70°C
LTC2912I.............................................. –40°C to 85°C
LTC2912H .......................................... –40°C to 125°C
Storage Temperature Range
TSOT.................................................. –65°C to 125°C
DFN.................................................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
TSOT................................................................. 300°C
PACKAGE/ORDER INFORMATION
TOP VIEW
TOP VIEW
LATCH
1
UV
2
OV
3
GND 4
8 V
CC
7 VH
6 VL
5 TMR
V
CC
1
VH 2
VL 3
TMR 4
9
8
LATCH
7
UV
6
OV
5 GND
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
T
JMAX
= 150°C,
θ
JA
= 195°C/W
DDB PACKAGE
8-LEAD (3mm × 2mm) PLASTIC DFN
T
JMAX
= 150°C,
θ
JA
= 76°C/W
EXPOSED PAD (PIN 9) IS GND, CONNECTION TO PCB OPTIONAL
ORDER PART NUMBER
LTC2912CTS8-1
LTC2912ITS8-1
LTC2912HTS8-1
TOP VIEW
DIS 1
UV
2
OV
3
GND 4
TS8 PART MARKING*
LTCJW
LTCJW
LTCJW
ORDER PART NUMBER
LTC2912CDDB-1
LTC2912IDDB-1
LTC2912HDDB-1
TOP VIEW
V
CC
1
VH 2
VL 3
TMR 4
9
DDB PART MARKING*
LCJZ
LCJZ
LCJZ
8 DIS
7
UV
6
OV
5 GND
8 V
CC
7 VH
6 VL
5 TMR
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
T
JMAX
= 150°C,
θ
JA
= 195°C/W
DDB PACKAGE
8-LEAD (3mm × 2mm) PLASTIC DFN
T
JMAX
= 150°C,
θ
JA
= 76°C/W
EXPOSED PAD (PIN 9) IS GND, CONNECTION TO PCB OPTIONAL
ORDER PART NUMBER
LTC2912CTS8-2
LTC2912ITS8-2
LTC2912HTS8-2
TOP VIEW
LATCH
1
UV
2
OV 3
GND 4
TS8 PART MARKING*
LTCJX
LTCJX
LTCJX
ORDER PART NUMBER
LTC2912CDDB-2
LTC2912IDDB-2
LTC2912HDDB-2
TOP VIEW
V
CC
1
VH 2
VL 3
TMR 4
9
DDB PART MARKING*
LCKB
LCKB
LCKB
8
LATCH
7
UV
6 OV
5 GND
8 V
CC
7 VH
6 VL
5 TMR
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
T
JMAX
= 150°C,
θ
JA
= 195°C/W
DDB PACKAGE
8-LEAD (3mm × 2mm) PLASTIC DFN
T
JMAX
= 150°C,
θ
JA
= 76°C/W
EXPOSED PAD (PIN 9) IS GND, CONNECTION TO PCB OPTIONAL
ORDER PART NUMBER
LTC2912CTS8-3
LTC2912ITS8-3
LTC2912HTS8-3
TS8 PART MARKING*
LTCJY
LTCJY
LTCJY
ORDER PART NUMBER
LTC2912CDDB-3
LTC2912IDDB-3
LTC2912HDDB-3
DDB PART MARKING*
LCKC
LCKC
LCKC
2912fa
Order Options
Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking:
http://www.linear.com/leadfree/
*The temperature grade is identified by a label on the shipping container.
2
LTC2912
ELECTRICAL CHARACTERISTICS
SYMBOL
V
SHUNT
ΔV
SHUNT
V
CC
V
CCR(MIN)
V
CC(UVLO)
ΔV
CC(UVHYST)
I
CC
V
UOT
t
UOD
I
VHL
t
UOTO
V
LATCH(VIH)
V
LATCH(VIL)
I
LATCH
I
DIS
V
DIS(VIH)
V
DIS(VIL)
I
TMR(UP)
I
TMR(DOWN)
V
TMR(DIS)
V
OH
V
OL
PARAMETER
V
CC
Shunt Regulator Voltage
V
CC
Shunt Regulator Load Regulation
Supply Voltage (Note 3)
Minimum V
CC
Output Valid
Supply Undervoltage Lockout
Supply Undervoltage Lockout Hysteresis
Supply Current
Undervoltage/Overvoltage Threshold
Undervoltage/Overvoltage Threshold to
Output Delay
VH, VL Input Current
–40°C < T
A
< 125°
UV/OV Time-Out Period
OV Latch Clear Input High
OV Latch Clear Input Low
LATCH
Input Current
DIS Input Current
DIS Input High
DIS Input Low
TMR Pull-Up Current
TMR Pull-Down Current
Timer Disable Voltage
Output Voltage High
UV/OV/OV
Output Voltage Low
UV/OV/OV
V
TMR
= 0V
–40°C < T
A
< 125°
V
TMR
= 1.6V
–40°C < T
A
< 125°
Referenced to V
CC
V
CC
= 2.3V, I
UV/OV
= –1μA
V
CC
= 2.3V, I
UV/OV
= 2.5mA
V
CC
= 1V, I
UV
= 100μA
V
LATCH
> 0.5V
V
DIS
> 0.5V
C
TMR
= 1nF
–40°C < T
A
< 125°
V
Hn
= V
UOT
– 5mV or V
Ln
= V
UOT
+ 5mV
DIS = 0V
DIS = 0V, V
CC
Rising
DIS = 0V
V
CC
= 2.3V to 6V
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 3.3V, VL = 0.45V, VH = 0.55V,
LATCH
= V
CC
unless otherwise
noted. (Note 2)
CONDITIONS
I
CC
= 5mA
–40°C < T
A
< 125°
I
CC
= 2mA to 10mA
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
MIN
6.2
6.2
2.3
1.9
5
492
50
TYP
6.6
6.6
200
MAX
7.2
7.3
300
V
SHUNT
1
UNITS
V
V
mV
V
V
V
mV
μA
mV
μs
nA
nA
ms
ms
V
V
μA
μA
V
V
μA
μA
μA
μA
mV
V
2
25
29
500
125
2.1
50
70
508
500
±15
±30
6
6
1.2
8.5
8.5
12.5
14
0.8
±1
1
1.2
2
3.3
0.8
–1.3
–1.2
1.3
1.2
–180
1
–2.1
–2.1
2.1
2.1
–270
0.10
0.01
–2.8
–2.8
2.8
2.8
0.30
0.15
V
V
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
All currents into pins are positive; all voltages are referenced to
GND unless otherwise noted.
Note 3:
V
CC
maximum pin voltage is limited by input current. Since the
V
CC
pin has an internal 6.5V shunt regulator, a low impedance supply that
exceeds 6V may exceed the rated terminal current. Operation from higher
voltage supplies requires a series dropping resistor. See Applications
Information.
2912fa
3
LTC2912
TIMING DIAGRAMS
VH Monitor Timing
VH
V
UOT
t
UOD
UV
1V
2912 TD01
VL Monitor Timing
VL
V
UOT
t
UOD
OV
1V
2912 TD02
t
UOTO
t
UOTO
VH Monitor Timing (TMR Pin Strapped to V
CC
)
VH
V
UOT
t
UOD
UV
1V
2912 TD03
VL Monitor Timing (TMR Pin Strapped to V
CC
)
VL
V
UOT
t
UOD
OV
1V
2912 TD04
t
UOD
t
UOD
TYPICAL PERFORMANCE CHARACTERISTICS
Input Threshold Voltage
vs Temperature
0.505
0.504
THRESHOLD VOLTAGE, V
UOT
(V)
0.503
0.502
I
CC
(μA)
0.501
0.500
0.499
0.498
0.497
0.496
0.495
–50
–25
25
50
0
TEMPERATURE (°C)
75
100
2912 G01
Supply Current vs Temperature
45
40
V
CC
= 5V
35
30
25
V
CC
= 2.3V
20
15
–50
V
CC
= 3.3V
V
CC
(V)
6.6
6.5
6.4
6.3
6.8
6.7
V
CC
Shunt Voltage
vs Temperature
10mA
5mA
2mA
1mA
200μA
–25
0
25
50
TEMPERATURE (°C)
75
100
2912 G02
6.2
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
2912 G03
V
CC
Shunt Voltage vs I
CC
6.75
TYPICAL TRANSIENT DURATION (μs)
700
600
500
400
300
200
100
Typical Transient Duration vs
Comparator Overdrive
0.8
UV
Output Voltage vs V
CC
6.65
V
CC
(V)
6.55
UV
VOLTAGE (V)
RESET OCCURS
ABOVE CURVE
0.6
V
CC
0.4
UV
WITH
10k PULL-UP
0.2
UV
WITHOUT
PULL-UP
0
0
0.2
0.6
0.8
0.4
SUPPLY VOLTAGE, V
CC
(V)
1
2912 G06
6.45
–40°C
6.35
25°C
85°C
6.25
–2
0
2
6
4
I
CC
(mA)
8
10
12
V
CC
= 6V
V
CC
= 2.3V
50
0.1
1
10
100
COMPARATOR OVERDRIVE PAST THRESHOLD (%)
2912 G05
2912 G04
2912fa
4
LTC2912
TYPICAL PERFORMANCE CHARACTERISTICS
UV
Output Voltage vs V
CC
5
UV/OV TIMEOUT PERIOD, t
UOTO
(ms)
VH = 0.55V
SEL = V
CC
10000
PULL-DOWN CURRENT, I
UV
(mA)
Reset Time-Out Period
vs Capacitance
5
UV,
I
SINK
vs V
CC
VH = 0.45V
SEL = V
CC
UV
AT 150mV
3
4
UV
VOLTAGE (V)
1000
4
3
100
2
2
UV
AT 50mV
1
1
10
0
0
1
3
4
2
SUPPLY VOLTAGE, V
CC
(V)
5
2912 G07
1
0.1
0
1
10
100
TMR PIN CAPACITANCE, C
TMR
(nF)
1000
2912 G08
0
1
3
4
2
SUPPLY VOLTAGE, V
CC
(V)
5
2912 G09
UV/OV,
Voltage Output Low
vs Output Sink Current
1.0
85°C
0.8
UV/OV,
V
OL
(V)
–40°C
0.6
25°C
UV/OV TIMEOUT PERIOD, t
OUTO
(ms)
12
11
10
9
8
7
Reset Timeout Period
vs Temperature
C
TMR
= 1nF
0.4
0.2
0
0
5
10
15
20
I
UV/OV
(mA)
25
30
1912 G10
6
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
2912 G11
PIN FUNCTIONS
(DFN/TSOT Packages)
DIS (Pin 8/Pin 1, LTC2912-2):
Output Disable Input.
Disables the
OV
and
UV
output pins. When DIS is pulled
high, the
OV
and
UV
pins are not asserted except during a
UVLO condition. Pin has a weak (2μA) internal pull-down
to GND. Leave pin open if unused.
Exposed Pad (Pin 9, DDB Package):
Exposed Pad may
be left open or connected to device ground.
GND (Pin 5/Pin 4):
Device Ground.
LATCH
(Pin 8/Pin 1, LTC2912-1, LTC2912-3):
OV/OV
Latch Clear/Bypass Input. When pulled high, OV/OV latch
is cleared. While held high, OV/OV has a similar delay and
output characteristic as
UV.
OV
(Pin 6/Pin 3, LTC2912-1, LTC2912-2):
Overvoltage
Logic Output. Asserts low when the VL input voltage is
above threshold. Latched low (LTC2912-1). Held low for
programmed delay time after VL input is valid (LTC2912-2).
Pin has a weak pull-up to V
CC
and may be pulled above V
CC
using an external pull-up. Leave pin open if unused.
2912fa
5
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