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 refer-
ence, 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 volt-
age window. The MAX6459 includes dual overvoltage/
undervoltage comparators with two independent com-
parator outputs. Use the MAX6459 as a window com-
parator with separate undervoltage and overvoltage
outputs or as two independent, single voltage monitors.
The MAX6460 includes a single comparator and an inter-
nal 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 active-
high 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 cir-
cuit with a 90ms minimum reset timeout delay. The moni-
tored 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 noise-
sensitive applications. Each device is available in a small
SOT23 package and specified over the extended temper-
ature range of -40°C to +125°C.
Applications
Undervoltage Monitoring/Shutdown
Overvoltage Monitoring/Protection
Window Voltage Detection Circuitry
Multicell Battery-Stack Powered Equipment
Notebooks, eBooks
Automotive
Industrial
Telecom
Networking
Features
♦Wide Supply Voltage Range, 4V to 28V
♦Internal 2.25V ±2.5% Reference
♦Low Current (3.5µA, typ at 12V)
♦Open-Drain N-Channel Output (28V Compliant)
♦Internal Threshold Hysteresis Options
(0.5%, 5%, 8.3%)
♦Two IN-to-OUT Timeout Period Options
(50µs, 150ms)
♦Internal Undervoltage Lockout
♦Immune to Short Voltage Transients
♦Small SOT23 Packages
♦Few External Components
♦Fully Specified from -40°C to +125°C
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
5-CELL
Li+
BATTERY
STACK
BATTERY
CHARGER
DC-DC
CONVERTER
LOAD
R1
R2
RPULLUP
SHDN
+21V (NOMINAL)
VCC
GND CLEAR
IN+ OUT
MAX6457
IN OUT
Typical Operating Circuit
19-2534; Rev 1; 6/03
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Pin Configurations appear at end of data sheet.
PART TEMP RANGE PIN-PACKAGE
MAX6457UKD_ _-T -40°C to +125°C 5 SOT23-5
MAX6458UKD_ _-T -40°C to +125°C 5 SOT23-5
MAX6459UT_-T -40°C to +125°C 6 SOT23-6
MAX6460UT-T -40°C to +125°C 6 SOT23-6
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 hys-
teresis 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.
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = 4V to 28V, TA= -40°C to +125°C, unless otherwise specified. Typical values are at TA= +25°C.) (Note 1)
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.
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
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Operating Voltage Range VCC (Note 2) 4 28 V
VCC = 5V, no load 2 5
VCC = 12V, no load 3.5 7.5Supply Current ICC
VCC = 24V, no load 6.5 12.5
µA
TA = -40°C to +85°C, VCC ≥ 4V 1.195 1.228 1.255
VTH+ VIN
rising TA = +85°C to +125°C, VCC ≥ 4V 1.170 1.255
TA = -40°C to +85°C 1.180 1.255
MAX645_U_D_A TA = +85°C to +125°C 1.155 1.255
TA = -40°C to +85°C 1.133 1.194
MAX645_U_D_B TA = +85°C to +125°C 1.111 1.194
TA = -40°C to +85°C 1.093 1.151
Threshold Voltage
VTH- VIN
falling
MAX645_U_D_C TA = +85°C to +125°C 1.071 1.151
V
MAX64_ _U_D_A 0.5
MAX64_ _U_D_B 5Threshold Voltage Hysteresis
MAX64_ _U_D_C 8.3
%VTH+
IN Operating Voltage Range VIN (Note 2) 0 VCC V
IN Leakage Current IIN VIN = 1.25V, VCC = +28V -55 +55 nA
MAX645_UKD0_
MAX6459UT_
MAX6460UT
50 µs
OUT Timeout Period tTP
MAX6457 and MAX6458 only,
D3 option 90 150 210 ms
Startup Time VCC rising from GND to VCC ≥ 4V in less than
1µs (Note 3) 2ms
VIL 0.4
CLEAR Input Logic Voltage
(MAX6457) VIH 2V
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
_______________________________________________________________________________________ 3
Note 1: Devices are production tested at +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.
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 SYMBOL CONDITIONS MIN TYP MAX UNITS
VCC ≥ 1.5V, ISINK = 250µA, OUT asserted,
TA = -40°C to +85°C0.4
Output Voltage Low VOL VCC ≥ 4.0V, ISINK = 1mA, OUT asserted,
TA = -40°C to +125°C0.4
V
Output Leakage Current ILKG VCC = 5V, VOUT = 28V (Note 4) 500 nA
Output Short-Circuit Sink ISC OUT asserted, OUT = VCC 10 mA
MAX6460
Reference Short-Circuit Current REF = GND 7 mA
TA = -40°C to +85°C 2.183 2.25 2.303
Reference Output Voltage VREF TA = +85°C to +125°C 2.171 2.25 2.303 V
Load Regulation Sourcing: 0 ≤ IREF ≤ 100µA,
sinking: 0 ≤ |IREF| ≤ 300nA 50 µV/µA
Input Offset Voltage VOFFSET -4.5 +4.5 mV
Input Hysteresis 6mV
Input Bias Current IBIAS VIN+ = 1.4V, VIN- = 1V -25 +25 nA
Input Offset Current IOFFSET 2pA
Common-Mode Voltage Range CMVR 0 1.4 V
Common-Mode Rejection Ratio CMRR 80 dB
Comparator Power-Supply
Rejection Ratio PSRR VIN+ = VIN- = 1.4V 80 dB
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
4 _______________________________________________________________________________________
Typical Operating Characteristics
(GND = 0, RPULLUP = 10kΩ, and TA= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX6457-60 toc01
VCC (V)
ICC (µA)
221610
2
4
6
8
10
12
0
428
TA = +25°C
TA = +125°C
TA = -40°C
TRIP THRESHOLD VOLTAGE
vs. TEMPERATURE (0.5% HYSTERESIS)
MAX6457-60 toc02
TEMPERATURE (°C)
TRIP THRESHOLD VOLTAGE (V)
1109580655035205-10-25
1.13
1.15
1.17
1.19
1.21
1.23
1.25
1.11
-40 125
VTH+ (RISING)
VTH- (FALLING)
TRIP THRESHOLD VOLTAGE
vs. TEMPERATURE (5% HYSTERESIS)
MAX6457-60 toc03
TEMPERATURE (°C)
TRIP THRESHOLD VOLTAGE (V)
1109580655035205-10-25
1.13
1.15
1.17
1.19
1.21
1.23
1.25
1.11
-40 125
VTH+ (RISING)
VTH- (FALLING)
TRIP THRESHOLD VOLTAGE
vs. TEMPERATURE (8.3% HYSTERESIS)
MAX6457-60 toc04
TEMPERATURE (°C)
TRIP THRESHOLD VOLTAGE (V)
1109580655035205-10-25
1.13
1.15
1.17
1.19
1.21
1.23
1.25
1.11
-40 125
VTH+ (RISING)
VTH- (FALLING)
OUTPUT LOW VOLTAGE
vs. OUTPUT SINK CURRENT
MAX6457-60 toc05
ISINK (mA)
VOL (mV)
1010.1
1
10
100
1000
10,000
100,000
0.1
0.01 100
TA = +125°C
TA = +25°C
TA = -40°C
VCC = 12V
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
_______________________________________________________________________________________ 5
OUTPUT SHORT-CIRCUIT SINK CURRENT
vs. TEMPERATURE
MAX6457-60 toc06
TEMPERATURE (°C)
ISC (mA)
1109580655035205-10-25
9
10
11
12
13
14
15
8
-40 125
VCC = 12V
VCC = 5V
VCC = 24V
TIMEOUT PERIOD vs. TEMPERATURE
MAX6457-60 toc07
TEMPERATURE (°C)
tTP (ms)
1109580655035205-10-25
0.1
1
10
100
1000
0.01
-40 125
MAX6457UKD3
MAX6457UKD0
OUTPUT FALL TIME
vs. SUPPLY VOLTAGE
MAX6457-60 toc08
VCC (V)
OUTPUT FALL TIME (ns)
242016128
200
400
600
800
1000
1200
1400
1600
1800
2000
0
428
TA = +125°C
TA = -40°C
TA = +25°C
MAXIMUM TRANSIENT DURATION
vs. INPUT OVERDRIVE
MAX6457-60 toc09
INPUT OVERDRIVE (VTH- - VIN+) (mV)
MAXIMUM TRANSIENT DURATION (µs)
10010
50
100
150
200
250
300
0
11000
OUT ASSERTED LOW
ABOVE THIS LINE
MAX6457-60 toc10
TEMPERATURE (°C)
IIN (nA)
1109580655035205-10-25
0
2
4
6
8
10
-2
-40 125
VIN = 1.25V
INPUT LEAKAGE CURRENT
vs. TEMPERATURE
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
6 _______________________________________________________________________________________
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+.
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 VIN-
drops below VTH-.
11—1 OUT
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
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 when VCC drops
below 4V.
—— 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
3333IN+
Adjustable Undervoltage Monitor Threshold Input. Noninverting input for
MAX6460.
—4 4 4 IN- Adjustable Overvoltage Monitor Threshold Input. Inverting input for
MAX6460.
4———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.
5566V
CC Supply Voltage
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
_______________________________________________________________________________________ 7
MAX6458
VCC
IN+
IN-
GND
OUT
1.228V
UV
OV
HYSTERESIS
OPTION
TIMEOUT
OPTION
"UV": UNDERVOLTAGE
"OV": OVERVOLTAGE
MAX6457
HYSTERESIS
OPTION
TIMEOUT
OPTION LATCH
VCC
IN+
GND
OUT
1.228V CLEAR
MAX6459
VCC
IN+
IN-
GND
1.228V
UV
OV
HYSTERESIS
OPTION
"UV": UNDERVOLTAGE
"OV": OVERVOLTAGE
OUTA
OUTB
MAX6460
VCC
IN+
IN-
REF
GND
2.25V
OUT
Functional Diagrams
Figure 1. MAX6457 Functional Diagram Figure 2. MAX6458 Functional Diagram
Figure 3. MAX6459 Functional Diagram Figure 4. MAX6460 Functional Diagram
MAX6457–MAX6460
Detailed Description
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 com-
parators, 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 10kΩand 1MΩ, then calculate R1 as follows:
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 volt-
age divider (within the inputs common-mode voltage
range) to REF. Small leakage currents into the com-
parators inputs allows use of large value resistors to
prevent loading the reference and affecting its accura-
cy. Figure 5b shows an active-high power-good output.
Use the following equation to determine the resistor val-
ues when connecting REF to IN-:
where VREF = reference output voltage (2.25V, typ),
VREFD = divided reference, VTRIP = desired trip thresh-
old 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.
RR V
V
TRIP
REFD
12 1=−
VV R
RR
REFD REF
=+
4
34
RR V
V
TRIP
TH
12 1=
-
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
8 _______________________________________________________________________________________
VCC
IN+
GND
OUT
(OUTB FOR
MAX6459)
R1
VCC
R2
RPULLUP
OUT
(OUTB)
MAX6457–
MAX6460
VTRIP = VTH R1 + R2
R2
Figure 5a. Programming the Trip Voltage
VCC
IN+
REF
IN-
GND
R1
VTRIP
VREFD
R2
R3
R4
RPULLUP
OUTOUT
MAX6460
Figure 5b. Programming the MAX6460 Trip Voltage
VTH+
VTH-
VIN+
VOUT
0
VCC
VHYST
tTP tTP
Figure 6. Input and Output Waveforms (Noninverting Input Varied)
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 hystere-
sis 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 volt-
age 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 requir-
ing 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
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.
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
_______________________________________________________________________________________ 9
IN+
OUT
>VTH+
<VTH-
VCC
VCC
0
0
tTP tTP tTP
CLEAR
Figure 7. Timing Diagram (MAX6457)
5-CELL
Li+
BATTERY
STACK
BATTERY
CHARGER
DC-DC
CONVERTER
LOAD
R1
R2
RPULLUP
IN OUT
+21V
VCC
GND
IN+ OUT
(OUTA FOR
MAX6459)
MAX6457–
MAX6460
SHDN
Figure 8. Undervoltage Lockout Typical Application Circuit
MAX6457–MAX6460
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 DC-
DC converter to cut off power to the load in case of an
undervoltage event. Select R1 and R2 to set the trip volt-
age (see the Programming the Trip Voltage 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.
Overvoltage Shutdown
The MAX6457–MAX6460 are ideal for overvoltage shut-
down applications. Figure 9 shows a typical circuit for
this application using a pass P-channel MOSFET. The
MAX6457–MAX6460 are powered directly from the sys-
tem voltage supply. Select R1 and R2 to set the trip volt-
age (see the Programming the Trip Voltage 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 over-
voltage 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.
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 con-
figuration 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 VTRIPLOW, OUTA asserts low while OUTB
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
10 ______________________________________________________________________________________
LOAD
R1
100kΩ
1µF
R2 RPULLUP
VCC
GND
IN+
OUT
(OUTB FOR
MAX6459)
MAX6457–
MAX6460
VSUPPLY
CLEAR
Figure 9. Overvoltage Shutdown Circuit (with External Pass
MOSFET)
LOAD
R1
R3
R2
VCC
FUSE
GND
IN+ OUT
(OUTB FOR
MAX6459)
MAX6457–
MAX6460
VSUPPLY
SCR
Figure 10. Overvoltage Shutdown Circuit (with SCR Fuse)
VCC
VCC
VCC
GND
VCC
R1
R2
R3
MAX6458
MAX6459
IN+
IN-
OUT
OUT
MAX6458
ONLY
OUTB
MAX6459
ONLY
RPULLUP
RPULLUP
RPULLUP
OUTA OUTA
OUTB
Figure 11. Window Detection
remains high. When VCC exceeds VTRIPHIGH, OUTB
asserts low while OUTA remains high. VTRIPLOW and
VTRIPHIGH are given by the following equations:
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 RTOTAL and the desired
upper trip point:
3) Calculate R2 based on RTOTAL, R3, and the desired
lower trip point:
4) Calculate R1 based on RTOTAL, R3, and R2:
R1 = RTOTAL - R2 - R3
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
3) Calculate R2
RVR
V
VM
V
k
TH TOTAL
TRIPHIGH
31 228 4 2
23 1
223 273
=×=Ω
=Ω
+ (. )(. )
.
.
RVR
VR
TH TOTAL
TRIPLOW
23=×
--
RVR
V
TH TOTAL
TRIPHIGH
3=×
+
VV
R
RR
VV
R
R
TRIPLOW TH TOTAL
TRIPHIGH TH TOTAL
=+
=
+
-23
3
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
______________________________________________________________________________________ 11
MAX6457–
MAX6460
VMON
VCC
VCC
R1
R2
GND
RPULLUP
IN+ OUT
(OUTB FOR
MAX6459)
OUT
(OUTB)
Figure 12. Monitoring Voltages Other than VCC
MAX6457–
MAX6460
VCC
GND
RPULLUP
OUT/
OUTA/
OUTB
OUT/
OUTA/
OUTB
VCC (4V TO 28V) VOUT (UP TO 28V)
Figure 13. Interfacing to Voltages Other than VCC
MAX6460
VCC
VCC
R1
R2
GND
VNEG
RPULLUP
IN+
REF
IN-
OUT OUT
Figure 14. Monitoring Negative Voltages
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
12 ______________________________________________________________________________________
PART SUFFIX TIMEOUT OPTION HYSTERESIS OPTION (%)
0A 50µs 0.5
0B 50µs 5
0C 50µs 8.3
3A 150ms 0.5
3B 150ms 5
MAX6457UKD_ _ -T
MAX6458UKD_ _ -T
3C 150ms 8.3
A 50µs 0.5
B 50µs 5MAX6459UT_ -T
C 50µs 8.3
MAX6460UT-T N/A 50µs 0.5
PART PIN
COUNT
LATCHED
OUTPUT
NUMBER OF
OUTPUTS
HYSTERESIS
(%VTH+)
TIMEOUT
PERIOD TOP MARK COMPARATORS
MAX6457UKD0A-T 5 ✓1 0.5 50µs AEAA 1
MAX6457UKD3A-T 5 ✓1 0.5 150ms AANN 1
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
Selector Guide
Table 1. Factory-Trimmed Internal Hysteresis and Timeout Period Options
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
______________________________________________________________________________________ 13
Chip Information
TRANSISTOR COUNT: 785
PROCESS: BiCMOS
GND
IN+
15V
CC
OUT
MAX6457
SOT23
TOP VIEW
2
34
GND
IN-IN+
16V
CC
5 OUTB
OUTA
MAX6459
SOT23
2
34
GND
IN-IN+
15V
CC
OUT
MAX6458
SOT23
2
34
GND
IN-IN+
16V
CC
5 REF
OUT
MAX6460
SOT23
2
34
CLEAR
Pin Configurations
4) Calculate R1
Monitoring Voltages Other than VCC
The MAX6457–MAX6460 can monitor voltages other than
VCC (Figure 12). Calculate VTRIP as shown in the
Programming the Trip Voltage section. The monitored volt-
age (VMON) is independent of VCC. VIN+ must be within
the specified operating range: 0 to VCC.
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).
Monitoring Negative Voltages
Figure 14 shows the typical application circuit for moni-
toring negative voltages (VNEG) using the MAX6460.
Select a value for R1 between 25kΩand 1MΩ. Use the
following equation to select R2:
where VREF = 2.25V and VNEG < 0. VIN+ must always
be within the specified operating range: 0 to VCC.
RRV
V
NEG
REF
21 =×
-
RR RR
Mkk
M
TOTAL
123
4 2 223 273 36 06
3 94067
. . .
.
=
=Ω Ω Ω
=Ω
- -
- -
RVR
VR
VM
Vk
k
TH TOTAL
TRIPLOW
23
1 167 4 2
18 9 223 273
36 06
=×
=ΩΩ
=
--
-
(. )(. )
..
. Ω
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
14 ______________________________________________________________________________________
SOT-23 5L .EPS
E
1
1
21-0057
PACKAGE OUTLINE, SOT-23, 5L
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX6457–MAX6460
High-Voltage, Low-Current Voltage Monitors in
SOT Packages
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
© 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
6LSOT.EPS
F
1
1
21-0058
PACKAGE OUTLINE, SOT-23, 6L
