Maxim MAX6460 High-voltage, low-current voltage monitors in sot package Datasheet

19-2534; Rev 4; 3/09
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
Features
o Wide Supply Voltage Range, 4V to 28V
o Internal 2.25V ±2.5% Reference
o Low Current (3.5µA, typ at 12V)
o Open-Drain n-Channel Output (28V Compliant)
o Internal Threshold Hysteresis Options
(0.5%, 5%, 8.3%)
o Two IN-to-OUT Timeout Period Options
(50µs, 150ms)
o Internal Undervoltage Lockout
o Immune to Short Voltage Transients
o Small SOT23 Packages
o Few External Components
o Fully Specified from -40°C to +125°C
Ordering Information
PART
TEMP RANGE
MAX6457UKD_ _-T
-40°C to +125°C
5 SOT23
MAX6458UKD_ _-T
-40°C to +125°C
5 SOT23
MAX6459UT_-T
-40°C to +125°C
6 SOT23
MAX6460UT-T
-40°C to +125°C
6 SOT23
Note: The MAX6457/MAX6458/MAX6459 are available with
factory-trimmed internal hysteresis options. The MAX6457 and
MAX6458 offer two fixed timing options. Select the desired hysteresis and timing options using Table 1 or the Selector Guide at
the end of the data sheet, and enter the corresponding letters
and numbers in the part number by replacing “_ _” or “_”. These
devices are offered in tape-and-reel only and must be ordered in
2500-piece increments.
Devices are available in both leaded and lead(Pb)-free/RoHScompliant packaging. Specify lead(Pb)-free by replacing “-T”
with “+T” when ordering.
Pin Configurations appear at end of data sheet.
Typical Operating Circuit
Applications
Undervoltage Monitoring/Shutdown
Overvoltage Monitoring/Protection
Window Voltage Detection Circuitry
Multicell Battery-Stack Powered Equipment
Notebooks, eBooks
Automotive
Industrial
Telecom
Networking
PIN-PACKAGE
BATTERY
CHARGER
+21V (NOMINAL)
IN
OUT
DC-DC
CONVERTER
SHDN
VCC
MAX6457
R1
5-CELL
Li+
BATTERY
STACK
IN+
RPULLUP
LOAD
OUT
R2
GND
CLEAR
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1
MAX6457–MAX6460
General Description
The MAX6457–MAX6460 high supply voltage, low-power
voltage monitors operate over a 4V to 28V supply voltage
range. Each device includes a precision bandgap reference, one or two low-offset voltage comparators, internal
threshold hysteresis, power-good or reset timeout
options, and one or two high-voltage open-drain outputs.
Two external resistors (three for window detection) set the
trip threshold voltages.
The MAX6457 is a single voltage monitor for undervoltage
or overvoltage detection. A logic-based clear input either
latches the output for overvoltage applications or allows
the device to operate in transparent mode. The MAX6458
includes two comparators (one overvoltage and one
undervoltage) for window detection and a single output to
indicate if the monitored input is within an adjustable voltage window. The MAX6459 includes dual overvoltage/
undervoltage comparators with two independent comparator outputs. Use the MAX6459 as a window comparator with separate undervoltage and overvoltage
outputs or as two independent, single voltage monitors.
The MAX6460 includes a single comparator and an internal reference, and can also accept an external reference.
The inverting and noninverting inputs of the comparator
are externally accessible to support positive or negative
voltage monitors and to configure the device for activehigh or active-low output logic.
The MAX6457/MAX6458 offer fixed timing options as a
voltage detector with a 50µs typical delay or as a reset circuit with a 90ms minimum reset timeout delay. The monitored input must be above the adjusted trip threshold (or
within the adjusted voltage window for the MAX6458) for
the selected timeout period before the output changes
state. The MAX6459/MAX6460 offer only a fixed 50µs
timeout period. Internal threshold hysteresis options (0.5%,
5%, and 8.3% for the MAX6457/MAX6458/MAX6459, and
0.5% for the MAX6460) reduce output chatter in noisesensitive applications. Each device is available in a small
SOT23 package and specified over the extended temperature range of -40°C to +125°C.
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
ABSOLUTE MAXIMUM RATINGS
VCC, OUT, OUTA, OUTB, CLEAR to GND ..........-0.3V to +30.0V
IN+, IN- to GND..........................................-0.3V to (VCC + 0.3V)
REF to GND..............-0.3V to the lower of +6V and (VCC + 0.3V)
Input Currents (VCC, IN+, IN-) ............................................20mA
Sink Current (OUT, OUTA, OUTB) ......................................20mA
Continuous Power Dissipation (TA = +70°C)
5-Pin SOT23 (derate 7.1 mW/°C above +70°C)............571mW
6-Pin SOT23 (derate 8.7 mW/°C above +70°C)............696mW
Junction Temperature ......................................................+150°C
Operating Temperature Range .........................-40°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VCC = 4V to 28V, TA = -40°C to +125°C, unless otherwise specified. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
Operating Voltage Range
VCC
Supply Current
ICC
CONDITIONS
(Note 2)
MIN
2
5
7.5
TA = -40°C to +85°C, VCC ≥ 4V
VIN
rising TA = +85°C to +125°C, VCC ≥ 4V
1.195
TA = -40°C to +85°C
1.180
1.255
TA = +85°C to +125°C
1.155
1.255
TA = -40°C to +85°C
1.133
1.194
1.111
1.194
TA = -40°C to +85°C
1.093
1.151
TA = +85°C to +125°C
1.071
1.151
5
MAX64_ _U_D_C
8.3
VIN
(Note 2)
IN Leakage Current
IIN
VIN = 1.25V, VCC = +28V
tTP
MAX645_UKD0_
MAX6459UT_
MAX6460UT
MAX6457 and MAX6458 only,
D3 option
2
V
%VTH+
0
VCC
V
-55
+55
nA
50
90
VCC rising from GND to VCC ≥ 4V in less than
1µs (Note 3)
150
µs
210
2
VIL
VIH
µA
0.5
MAX64_ _U_D_B
IN Operating Voltage Range
CLEAR Input Logic Voltage
(MAX6457)
12.5
1.255
1.255
MAX64_ _U_D_A
Startup Time
6.5
1.228
1.170
VIN
MAX645_U_D_B
falling
TA = +85°C to +125°C
MAX645_U_D_C
OUT Timeout Period
V
3.5
Threshold Voltage
Threshold Voltage Hysteresis
UNITS
28
VCC = 12V, no load
MAX645_U_D_A
VTH-
MAX
VCC = 5V, no load
VCC = 24V, no load
VTH+
TYP
4
ms
0.4
2
_______________________________________________________________________________________
ms
V
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
MAX6457–MAX6460
ELECTRICAL CHARACTERISTICS (continued)
(VCC = 4V to 28V, TA = -40°C to +125°C, unless otherwise specified. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
Output Voltage Low
SYMBOL
VOL
Output Leakage Current
Output Short-Circuit Sink
ILKG
ISC
CONDITIONS
MIN
TYP
MAX
VCC ≥ 1.5V, ISINK = 250µA, OUT asserted,
TA = -40°C to +85°C
0.4
VCC ≥ 4.0V, ISINK = 1mA, OUT asserted,
TA = -40°C to +125°C
0.4
UNITS
V
VCC = 5V, VOUT = 28V (Note 4)
500
OUT asserted, OUT = VCC
10
nA
mA
MAX6460
Reference Short-Circuit Current
Reference Output Voltage
REF = GND
VREF
7
2.183
2.25
2.303
TA = +85°C to +125°C
2.171
2.25
2.303
Sourcing: 0 ≤ IREF ≤ 100µA,
sinking: 0 ≤ |IREF| ≤ 300nA
Load Regulation
Input Offset Voltage
mA
TA = -40°C to +85°C
VOFFSET
50
-4.5
Input Hysteresis
µV/µA
+4.5
6
Input Bias Current
IBIAS
Input Offset Current
VIN+ = 1.4V, VIN- = 1V
-25
IOFFSET
Common-Mode Voltage Range
CMVR
Common-Mode Rejection Ratio
CMRR
Comparator Power-Supply
Rejection Ratio
PSRR
2
VIN+ = VIN- = 1.4V
mV
mV
+25
0
V
nA
pA
1.4
V
80
dB
80
dB
Note 1: Devices are production tested at TA = +25°C. Overtemperature limits are guaranteed by design.
Note 2: IN voltage monitoring requires that VCC ≥ 4V, but OUT remains asserted in the correct undervoltage lockout state for VCC
down to 1.5V.
Note 3: Startup time is the time required for the internal regulator and reference to reach specified accuracy after the monitor is
powered up from GND.
Note 4: The open-drain output can be pulled up to a voltage greater than VCC but cannot exceed +28V.
_______________________________________________________________________________________
3
Typical Operating Characteristics
(GND = 0, RPULLUP = 10kΩ, and TA = +25°C, unless otherwise noted.)
TA = +25°C
6
4
TA = -40°C
2
1.21
VTH- (FALLING)
1.19
1.17
1.15
10
16
22
28
VTH- (FALLING)
TEMPERATURE (°C)
OUTPUT LOW VOLTAGE
vs. OUTPUT SINK CURRENT
100,000
10,000
TA = +125°C
VTH+ (RISING)
1000
VOL (mV)
1.19
1.17
1.15
1.15
-40 -25 -10 5 20 35 50 65 80 95 110 125
MAX6457-60 toc04
TRIP THRESHOLD VOLTAGE (V)
1.21
1.17
TEMPERATURE (°C)
TRIP THRESHOLD VOLTAGE
vs. TEMPERATURE (8.3% HYSTERESIS)
1.23
VTH+ (RISING)
1.19
-40 -25 -10 5 20 35 50 65 80 95 110 125
VCC (V)
1.25
1.21
1.11
1.11
4
1.23
1.13
1.13
0
MAX6457-60 toc03
1.23
1.25
MAX6457-60 toc05
TA = +125°C
VTH+ (RISING)
TRIP THRESHOLD VOLTAGE (V)
8
MAX6457-60 toc02
10
1.25
TRIP THRESHOLD VOLTAGE (V)
MAX6457-60 toc01
12
TRIP THRESHOLD VOLTAGE
vs. TEMPERATURE (5% HYSTERESIS)
TRIP THRESHOLD VOLTAGE
vs. TEMPERATURE (0.5% HYSTERESIS)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
ICC (µA)
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
TA = +25°C
100
TA = -40°C
10
VTH- (FALLING)
1.13
1
1.11
0.1
VCC = 12V
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
4
0.01
0.1
1
10
100
ISINK (mA)
_______________________________________________________________________________________
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
100
tTP (ms)
MAX6457UKD3
12
VCC = 5V
10
11
1
MAX6457UKD0
10
VCC = 24V
0.1
1800
TA = +125°C
1600
1400
1200
1000
800
600
TA = +25°C
400
9
TA = -40°C
200
0.01
8
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
4
8
12
TEMPERATURE (°C)
MAXIMUM TRANSIENT DURATION
vs. INPUT OVERDRIVE
24
28
10
MAX6457-60 toc10
250
20
INPUT LEAKAGE CURRENT
vs. TEMPERATURE
MAX6457-60 toc09
300
16
VCC (V)
TEMPERATURE (°C)
VIN = 1.25V
8
200
6
IIN (nA)
MAXIMUM TRANSIENT DURATION (µs)
ISC (mA)
13
2000
OUTPUT FALL TIME (ns)
VCC = 12V
MAX6457-60 toc07
14
1000
MAX6457-60 toc06
15
OUTPUT FALL TIME
vs. SUPPLY VOLTAGE
TIMEOUT PERIOD vs. TEMPERATURE
MAX6457-60 toc08
OUTPUT SHORT-CIRCUIT SINK CURRENT
vs. TEMPERATURE
150
100
4
2
OUT ASSERTED LOW
ABOVE THIS LINE
50
0
0
-2
1
10
100
INPUT OVERDRIVE (VTH- - VIN+) (mV)
1000
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
_______________________________________________________________________________________
5
MAX6457–MAX6460
Typical Operating Characteristics (continued)
(GND = 0, RPULLUP = 10kΩ, and TA = +25°C, unless otherwise noted.)
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
Pin Description
PIN
MAX6457
MAX6458
MAX6459
MAX6460
NAME
FUNCTION
MAX6457: Open-Drain Monitor Output. OUT requires an external pullup
resistor. OUT asserts low for VCC between 1.5V and 4V. OUT asserts low
when VIN+ drops below VTH- and goes high after the timeout period (tTP)
when VIN+ exceeds VTH+.
1
1
—
1
OUT
MAX6458: Open-Drain Monitor Output. OUT requires an external pullup
resistor. OUT asserts low for VCC between 1.5V and 4V. OUT asserts low
when VIN+ drops below VTH- or when VIN- exceeds VTH+. OUT goes
high after the timeout period (tTP) when VIN+ exceeds VTH+ and VINdrops below VTH-.
MAX6460: Open-Drain Monitor Output. OUT requires an external pullup
resistor. OUT asserts low for VCC between 1.5V and 4V. OUT asserts low
when VIN+ drops below VIN-. OUT goes high when VIN+ is above VIN-.
—
1
—
OUTA
—
—
5
—
OUTB
Open-Drain Monitor B Overvoltage Output. OUTB requires an external
pullup resistor. OUTB goes low when VIN- exceeds VTH+ and goes high
when VIN- drops below VTH-. OUTB also goes low when VCC drops
below 4V.
2
2
2
2
GND
Ground
3
3
3
3
IN+
Adjustable Undervoltage Monitor Threshold Input. Noninverting input for
MAX6460.
—
4
4
4
IN-
Adjustable Overvoltage Monitor Threshold Input. Inverting input for
MAX6460.
4
6
—
Open-Drain Monitor A Undervoltage Output. OUTA requires an external
pullup resistor. OUTA goes low when VIN+ drops below VTH- and goes
high when VIN+ exceeds VTH+. OUTA also goes low for VCC between
1.5V and 4V.
—
—
—
CLEAR
Clear Input. For VIN+ > VTH+, drive CLEAR high to latch OUT high.
Connect CLEAR to GND to make the latch transparent. CLEAR must be
low when powering up the device. Connect CLEAR to GND when not
used.
—
—
—
5
REF
Reference. Internal 2.25V reference output. Connect REF to IN+ through
a voltage divider for active-low output. Connect REF to IN- through a
voltage divider for active-high output. REF can source up to 100µA and
sink up to 300nA. Leave REF floating when not used. REF output is
stable with capacitive loads from 0 to 50pF or greater than 1µF.
5
5
6
6
VCC
Supply Voltage
_______________________________________________________________________________________
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
VCC
VCC
IN+
MAX6458
UV
MAX6457
TIMEOUT
OPTION
IN+
TIMEOUT
OPTION
LATCH
OUT
HYSTERESIS
OPTION
OUT
INOV
HYSTERESIS
OPTION
1.228V
CLEAR
1.228V
"UV": UNDERVOLTAGE
"OV": OVERVOLTAGE
GND
GND
Figure 2. MAX6458 Functional Diagram
Figure 1. MAX6457 Functional Diagram
VCC
VCC
IN+
MAX6459
OUTA
UV
IN+
OUT
IN-
INOUTB
OV
REF
MAX6460
HYSTERESIS
OPTION
2.25V
1.228V
"UV": UNDERVOLTAGE
"OV": OVERVOLTAGE
GND
GND
Figure 3. MAX6459 Functional Diagram
Figure 4. MAX6460 Functional Diagram
_______________________________________________________________________________________
7
MAX6457–MAX6460
Functional Diagrams
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
Detailed Description
⎛ R4 ⎞
VREFD = VREF ⎜
⎟
⎝ R 3 + R4 ⎠
Each of the MAX6457–MAX6460 high-voltage (4V to
28V), low-power voltage monitors include a precision
bandgap reference, one or two low-offset-voltage comparators, internal threshold hysteresis, internal timeout
period, and one or two high-voltage open-drain outputs.
Programming the Trip Voltage (VTRIP)
Two external resistors set the trip voltage, VTRIP (Figure 5).
VTRIP is the point at which the applied voltage (typically
VCC) toggles OUT. The MAX6457/MAX6458/MAX6459/
MAX6460’s high input impedance allows large-value
resistors without compromising trip-voltage accuracy.
To minimize current consumption, select a value for R2
between 10kΩ and 1MΩ, then calculate R1 as follows:
⎛V
⎞
R1 = R2 ⎜ TRIP - 1⎟
⎝ VTH
⎠
⎛V
⎞
R1= R2 ⎜ TRIP − 1⎟
⎝ VREFD ⎠
where VREF = reference output voltage (2.25V, typ),
VREFD = divided reference, VTRIP = desired trip threshold in (in volts).
For an active-low power-good output, connect the
resistor divider R1 and R2 to the inverting input and the
reference-divider network to the noninverting input.
Alternatively, connect an external reference less than
1.4V to either input.
VTRIP
VCC
VCC
RPULLUP
R1
VCC
RPULLUP
R1
MAX6457–
MAX6460
IN+
R2
OUT
(OUTA FOR
MAX6459)
IN+
OUT
(OUTA)
REF
VREFD
GND
VTRIP = VTH
MAX6460
R3
OUT
OUT
R2
INGND
R4
R1 + R2
R2
Figure 5a. Programming the Trip Voltage
Figure 5b. Programming the MAX6460 Trip Voltage
where VTRIP = desired trip voltage (in volts), VTH =
threshold trip voltage (VTH+ for overvoltage detection
or VTH- for undervoltage detection).
Use the MAX6460 voltage reference (REF) to set the
trip threshold by connecting IN+ or IN- through a voltage divider (within the inputs common-mode voltage
range) to REF. Do not connect REF directly to IN+ or
IN- since this violates the input common-mode voltage
range. Small leakage currents into the comparators
inputs allows use of large value resistors to prevent
loading the reference and affecting its accuracy. Figure
5b shows an active-high power-good output. Use the
following equation to determine the resistor values
when connecting REF to IN-:
8
VHYST
VTH+
VIN+
VTH-
VCC
VOUT
0
tTP
tTP
Figure 6. Input and Output Waveforms (Noninverting Input Varied)
_______________________________________________________________________________________
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
MAX6457–MAX6460
>VTH+
IN+
<VTH-
VCC
CLEAR
0
VCC
OUT
tTP
tTP
tTP
0
Figure 7. Timing Diagram (MAX6457)
Hysteresis
Hysteresis adds noise immunity to the voltage monitors
and prevents oscillation due to repeated triggering
when VIN is near the threshold trip voltage. The hysteresis in a comparator creates two trip points: one for the
rising input voltage (VTH+) and one for the falling input
voltage (VTH-). These thresholds are shown in Figure 6.
The internal hysteresis options of the MAX6457/
MAX6458/MAX6459 are designed to eliminate the need
for adding an external hysteresis circuit.
Timeout Period
The timeout period (tTP) for the MAX6457 is the time
from when the input (IN+) crosses the rising input
threshold (VTH+) to when the output goes high (see
Figures 6 and 7). For the MAX6458, the monitored voltage must be in the “window” before the timeout starts.
The MAX6459 and MAX6460 do not offer the extended
timeout option (150ms). The extended timeout period is
suitable for overvoltage protection applications requiring transient immunity to avoid false output assertion
due to noise spikes.
Latched-Output Operation
The MAX6457 features a digital latch input (CLEAR) to
latch any overvoltage event. If the voltage on IN+ (VIN+)
is below the internal threshold (VTH-), or if VCC is below
BATTERY
CHARGER
+21V
IN
OUT
DC-DC
CONVERTER
SHDN
VCC
MAX6457–
MAX6460
R1
5-CELL
Li+
BATTERY
STACK
IN+
R2
RPULLUP
LOAD
OUT
(OUTA FOR
MAX6459)
GND
Figure 8. Undervoltage Lockout Typical Application Circuit
4V, OUT remains low regardless of the state of CLEAR.
Drive CLEAR high to latch OUT high when VIN+ exceeds
VTH+. When CLEAR is high, OUT does not deassert if
VIN+ drops back below VIN-. Toggle CLEAR to deassert
OUT. Drive CLEAR low to make the latch transparent
(Figure 7). CLEAR must be low when powering up the
MAX6457. To initiate self-clear at power-up, add a 100kΩ
pullup resistor from CLEAR to VCC and a 1µF capacitor
from CLEAR to GND to hold CLEAR low. Connect
CLEAR to GND when not used. See Figure 9.
_______________________________________________________________________________________
9
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
FUSE
VSUPPLY
VSUPPLY
R1
VCC
VCC
LOAD
IN+
100kΩ
MAX6457–
MAX6460
R2
CLEAR
RPULLUP
LOAD
OUT
(OUTA FOR
MAX6459)
GND
Figure 9. Overvoltage Shutdown Circuit (with External Pass
MOSFET)
Applications Information
Undervoltage Lockout
Figure 8 shows the typical application circuit for detecting
an undervoltage event of a 5-cell Li+ battery stack.
Connect OUT of the MAX6457/MAX6458/MAX6460
(OUTA of the MAX6459) to the shutdown input of the DCDC converter to cut off power to the load in case of an
undervoltage event. Select R1 and R2 to set the trip voltage (see the Programming the Trip Voltage (VTRIP) section). When the voltage of the battery stack decreases so
that VIN+ drops below VTH- of the MAX6457–MAX6460,
then OUT (OUTA) goes low and disables the power supply to the load. When the battery charger restores the voltage of the 5-cell stack so that VIN+ > VTH+, OUT (OUTA)
goes high and the power supply resumes driving the load.
GND
Figure 10. Overvoltage Shutdown Circuit (with SCR Fuse)
Window Detection
The MAX6458/MAX6459 include undervoltage and
overvoltage comparators for window detection (Figures
2 and 3). The circuit in Figure 11 shows the typical configuration for this application. For the MAX6458, OUT
asserts high when VCC is within the selected “window.”
When VCC falls below the lower limit of the window
(VTRIPLOW) or exceeds the upper limit (VTRIPHIGH),
OUT asserts low.
The MAX6459 features two independent open-drain
outputs: OUTA (for undervoltage events) and OUTB (for
overvoltage events). When VCC is within the selected
window, OUTA and OUTB assert high. When VCC falls
below V TRIPLOW , OUTA asserts low while OUTB
VCC
Overvoltage Shutdown
The MAX6457–MAX6460 are ideal for overvoltage shutdown applications. Figure 9 shows a typical circuit for
this application using a pass P-channel MOSFET. The
MAX6457–MAX6460 are powered directly from the system voltage supply. Select R1 and R2 to set the trip voltage (see the Programming the Trip Voltage (V TRIP)
section). When the supply voltage remains below the
selected threshold, a low logic level on OUT (OUTB for
MAX6459) turns on the p-channel MOSFET. In the case
of an overvoltage event, OUT (OUTB) asserts high, turns
off the MOSFET, and shuts down the power to the load.
Figure 10 shows a similar application using a fuse and
a silicon-controlled rectifier (SCR). An overvoltage
event turns on the SCR and shorts the supply to
ground. The surge of current through the short circuit
blows the fuse and terminates the current to the load.
Select R3 so that the gate of the SCR is properly biased
when OUT (OUTB) goes high impedance.
10
SCR
OUT
(OUTA FOR
MAX6459)
IN+
R2
1µF
R3
MAX6457–
MAX6460
R1
VCC
VCC
RPULLUP
OUT
MAX6458
ONLY
R1
OUT
VCC
IN+
MAX6458
MAX6459
R2
RPULLUP
INR3
RPULLUP
OUTA
OUTA
OUTB
MAX6459
ONLY
OUTB
GND
Figure 11. Window Detection
______________________________________________________________________________________
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
⎛R
⎞
VTRIPLOW = VTH- ⎜ TOTAL ⎟
⎝ R2 + R3 ⎠
⎛R
⎞
VTRIPHIGH = VTH+ ⎜ TOTAL ⎟
⎝ R3 ⎠
where RTOTAL = R1 + R2 + R3.
Use the following steps to determine the values for R1,
R2, and R3.
1) Choose a value for RTOTAL, the sum of R1, R2, and
R3. Because the MAX6458/MAX6459 have very
high input impedance, RTOTAL can be up to 5MΩ.
2) Calculate R3 based on R TOTAL and the desired
upper trip point:
V
× RTOTAL
R3 = TH+
VTRIPHIGH
3) Calculate R2 based on RTOTAL, R3, and the desired
lower trip point:
Example Calculations for Window
Detection
The following is an example for calculating R1, R2, and
R3 of Figure 11 for window detection. Select the upper
and lower trip points (VTRIPHIGH and VTRIPLOW).
VCC = 21V
VTRIPHIGH = 23.1V
VTRIPLOW = 18.9V
For 5% hysteresis, VTH+ = 1.228 and VTH- = 1.167.
1) Choose RTOTAL = 4.2MΩ = R1 + R2 + R3
2) Calculate R3
R3 =
VTH+ × RTOTAL
(1.228V) (4.2MΩ)
=
VTRIPHIGH
23.1V
= 223.273kΩ
3) Calculate R2
VOUT (UP TO 28V)
VCC (4V TO 28V)
VCC
RPULLUP
V
× RTOTAL
R2 = TH- R3
VTRIPLOW
MAX6457–
MAX6460
OUT/
OUTA/
OUTB
OUT/
OUTA/
OUTB
4) Calculate R1 based on RTOTAL, R3, and R2:
R1 = RTOTAL - R2 - R3
GND
Figure 13. Interfacing to Voltages Other than VCC
VCC
VCC
VMON
VCC
VCC
INRPULLUP
RPULLUP
R1
MAX6457–
MAX6460
IN+
R2
OUT
(OUTA FOR
MAX6459)
MAX6460
OUT
OUT
(OUTA)
OUT
REF
R1
IN+
GND
GND
R2
VNEG
Figure 12. Monitoring Voltages Other than VCC
Figure 14. Monitoring Negative Voltages
______________________________________________________________________________________
11
MAX6457–MAX6460
remains high. When VCC exceeds VTRIPHIGH, OUTB
asserts low while OUTA remains high. VTRIPLOW and
VTRIPHIGH are given by the following equations:
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
Table 1. Factory-Trimmed Internal Hysteresis and Timeout Period Options
PART
SUFFIX
TIMEOUT OPTION
HYSTERESIS OPTION (%)
0A
50µs
0.5
MAX6457UKD_ _ -T
MAX6458UKD_ _ -T
MAX6459UT_ -T
MAX6460UT-T
0B
50µs
5
0C
50µs
8.3
3A
150ms
0.5
3B
150ms
5
3C
150ms
8.3
A
50µs
0.5
B
50µs
5
C
50µs
8.3
N/A
50µs
0.5
Selector Guide
TIMEOUT
PERIOD
PIN
COUNT
LATCHED
OUTPUT
NUMBER OF
OUTPUTS
HYSTERESIS
(%VTH+)
MAX6457UKD0A-T
5
✓
1
0.5
MAX6457UKD3A-T
5
✓
1
0.5
MAX6457UKD0B-T
5
✓
1
5
50µs
AANL
1
MAX6457UKD3B-T
5
✓
1
5
150ms
AANO
1
MAX6457UKD0C-T
5
✓
1
8.3
50µs
AANM
1
MAX6457UKD3C-T
5
✓
1
8.3
150ms
ADZZ
1
MAX6458UKD0A-T
5
—
1
0.5
50µs
AANP
2
MAX6458UKD3A-T
5
—
1
0.5
150ms
AANS
2
MAX6458UKD0B-T
5
—
1
5
50µs
AANQ
2
MAX6458UKD3B-T
5
—
1
5
150ms
AEAB
2
MAX6458UKD0C-T
5
—
1
8.3
50µs
AANR
2
MAX6458UKD3C-T
5
—
1
8.3
150ms
AANT
2
MAX6459UTA-T
6
—
2
0.5
50µs
ABML
2
MAX6459UTB-T
6
—
2
5
50µs
ABEJ
2
MAX6459UTC-T
6
—
2
8.3
50µs
ABMM
2
MAX6460UT-T
6
—
1
0.5
50µs
ABEG
1
PART
12
TOP MARK
COMPARATORS
50µs
AEAA
1
150ms
AANN
1
______________________________________________________________________________________
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
Interfacing to Voltages Other than VCC
The open-drain outputs of the MAX6457–MAX6460
allow the output voltage to be selected independent of
VCC. For systems requiring an output voltage other than
VCC, connect the pullup resistor between OUT, OUTA, or
OUTB and any desired voltage up to 28V (see Figure 13).
VTH- × RTOTAL
- R3
VTRIPLOW
(1.167V) (4.2MΩ)
- 223.273kΩ
18.9V
= 36.06kΩ
=
Monitoring Negative Voltages
4) Calculate R1
Figure 14 shows the typical application circuit for monitoring negative voltages (VNEG) using the MAX6460.
Select a value for R1 between 25kΩ and 1MΩ. Use the
following equation to select R2:
R1 = RTOTAL - R2 - R3
= 4.2MΩ - 223.273kΩ - 36.06kΩ
= 3.94067MΩ
R2 = R1 ×
Monitoring Voltages Other than VCC
The MAX6457–MAX6460 can monitor voltages other than
V CC (Figure 12). Calculate V TRIP as shown in the
Programming the Trip Voltage (VTRIP) section. The monitored voltage (VMON) is independent of VCC. VIN+ must
be within the specified operating range: 0 to VCC.
-VNEG
VREF
where VREF = 2.25V and VNEG < 0. VIN+ must always
be within the specified operating range: 0 to VCC.
Pin Configurations
TOP VIEW
OUT 1
GND 2
5
VCC
MAX6457
IN+ 3
OUT 1
GND 2
4
CLEAR
OUTA 1
GND 2
MAX6459
IN+ 3
SOT23
VCC
4
IN-
6
VCC
5
REF
4
IN-
MAX6458
IN+ 3
SOT23
5
SOT23
6
VCC
OUT 1
5
OUTB
GND 2
4
IN-
MAX6460
IN+ 3
SOT23
______________________________________________________________________________________
13
MAX6457–MAX6460
R2 =
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
Package Information
Chip Information
TRANSISTOR COUNT: 785
PROCESS: BiCMOS
14
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
5 SOT23
U5-1
21-0057
6 SOT23
U5-1
21-0058
______________________________________________________________________________________
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
REVISION
NUMBER
REVISION
DATE
0
7/02
Initial release
1
6/03
Updated the Pin Description and Detailed Description sections.
2
12/05
Added lead-free notation to Ordering Information.
3
1/07
Updated the Pin Description and Figures 5a, 9, 12.
4
3/09
Updated the Programming the Trip Voltage (VTRIP) section.
DESCRIPTION
PAGES
CHANGED
—
6, 8
1
6, 8, 10, 11, 13-16
8
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15
© 2009 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
MAX6457–MAX6460
Revision History