MAX6458UKD0B+ - Maxim Integrated Products, Inc.

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

oWide Supply Voltage Range, 4V to 28V

oInternal 2.25V ±2.5% Reference

oLow Current (3.5µA, typ at 12V)

oOpen-Drain n-Channel Output (28V Compliant)

oInternal Threshold Hysteresis Options

(0.5%, 5%, 8.3%)

oTwo IN-to-OUT Timeout Period Options

(50µs, 150ms)

oInternal Undervoltage Lockout

oImmune to Short Voltage Transients

oSmall SOT23 Packages

oFew External Components

oFully Specified from -40°C to +125°C

MAX6457–MAX6460

High-Voltage, Low-Current Voltage Monitors in

SOT Packages

________________________________________________________________

Maxim Integrated Products

Ordering Information

5-CELL

Li+

BATTERY

STACK

BATTERY

CHARGER

DC-DC

CONVERTER

LOAD

RPULLUP

SHDN

+21V (NOMINAL)

VCC

GND CLEAR

IN+ OUT

MAX6457

IN OUT

Typical Operating Circuit

19-2534; Rev 4; 3/09

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.

Pin Configurations appear at end of data sheet.

PART TEMP RANGE PIN-PACKAGE

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 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.

Devices are available in both leaded and lead(Pb)-free/RoHS-

compliant packaging. Specify lead(Pb)-free by replacing “-T”

with “+T” when ordering.

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

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 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.

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°C 0.4

Output Voltage Low VOL VCC ≥ 4.0V, ISINK = 1mA, OUT asserted,

TA = -40°C to +125°C 0.4

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

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

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

_______________________________________________________________________________________

OUTPUT SHORT-CIRCUIT SINK CURRENT

vs. TEMPERATURE

MAX6457-60 toc06

TEMPERATURE (

ISC (mA)

1109580655035205-10-25

-40 125

VCC = 12V

VCC = 5V

VCC = 24V

TIMEOUT PERIOD vs. TEMPERATURE

MAX6457-60 toc07

TEMPERATURE (°C)

tTP (ms)

1109580655035205-10-25

0.1

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

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

100

150

200

250

300

11000

OUT ASSERTED LOW

ABOVE THIS LINE

MAX6457-60 toc10

TEMPERATURE (°C)

IIN (nA)

1109580655035205-10-25

-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

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-.

1 1 — 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 for VCC between

1.5V and 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

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

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. 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-:

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

TRIP

REFD

12 1=−

⎛

⎝

⎜⎞

⎠

⎟

VV R

REFD REF

⎛

⎝

⎜⎞

⎠

⎟

RR V

TRIP

12 1=⎛

⎝

⎜⎞

⎠

⎟

High-Voltage, Low-Current Voltage Monitors in

SOT Packages

8 _______________________________________________________________________________________

VCC

IN+

GND

OUT

(OUTA FOR

MAX6459)

VCC

RPULLUP

OUT

(OUTA)

MAX6457–

MAX6460

VTRIP = VTH R1 + R2

Figure 5a. Programming the Trip Voltage

VCC

IN+

REF

IN-

GND

VTRIP

VREFD

RPULLUP

OUTOUT

MAX6460

Figure 5b. Programming the MAX6460 Trip Voltage

VTH+

VTH-

VIN+

VOUT

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

tTP tTP tTP

CLEAR

Figure 7. Timing Diagram (MAX6457)

5-CELL

Li+

BATTERY

STACK

BATTERY

CHARGER

DC-DC

CONVERTER

LOAD

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 (V

TRIP

)

sec-

tion). 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 sup-

ply to the load. When the battery charger restores the volt-

age 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 (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.

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

100kΩ

1µF

R2 RPULLUP

VCC

GND

IN+

OUT

(OUTA FOR

MAX6459)

MAX6457–

MAX6460

VSUPPLY

CLEAR

Figure 9. Overvoltage Shutdown Circuit (with External Pass

MOSFET)

LOAD

VCC

FUSE

GND

IN+ OUT

(OUTA FOR

MAX6459)

MAX6457–

MAX6460

VSUPPLY

SCR

Figure 10. Overvoltage Shutdown Circuit (with SCR Fuse)

VCC

GND

VCC

MAX6458

MAX6459

IN+

IN-

OUT

MAX6458

ONLY

OUTB

MAX6459

ONLY

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

TH TOTAL

TRIPHIGH

31 228 4 2

23 1

223 273

=×=Ω

=Ω

+ (. )(. )

RVR

TH TOTAL

TRIPLOW

23=×

RVR

TH TOTAL

TRIPHIGH

3=×

TRIPLOW TH TOTAL

TRIPHIGH TH TOTAL

⎛

⎝

⎜⎞

⎠

⎟

=⎛

⎝

⎜⎞

⎠

⎟

-23

MAX6457–MAX6460

High-Voltage, Low-Current Voltage Monitors in

SOT Packages

______________________________________________________________________________________ 11

MAX6457–

MAX6460

VMON

VCC

GND

RPULLUP

IN+ OUT

(OUTA FOR

MAX6459)

OUT

(OUTA)

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

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

GND

IN+

15V

OUT

MAX6457

SOT23

TOP VIEW

GND

IN-IN+

16V

5 OUTB

OUTA

MAX6459

SOT23

GND

IN-IN+

15V

OUT

MAX6458

SOT23

GND

IN-IN+

16V

5 REF

OUT

MAX6460

SOT23

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 (V

TRIP

)

section. The moni-

tored voltage (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

NEG

REF

21 =×

RR RR

Mkk

TOTAL

123

4 2 223 273 36 06

3 94067

. . .

=Ω Ω Ω

=Ω

- -

RVR

TH TOTAL

TRIPLOW

1 167 4 2

18 9 223 273

36 06

=×

=ΩΩ

(. )(. )

. Ω

MAX6457–MAX6460

High-Voltage, Low-Current Voltage Monitors in

SOT Packages

14 ______________________________________________________________________________________

Package Information

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

Chip Information

TRANSISTOR COUNT: 785

PROCESS: BiCMOS

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 ____________________

Revision History

REVISION

NUMBER

REVISION

DATE DESCRIPTION PAGES

CHANGED

0 7/02 Initial release —

1 6/03 Updated the Pin Description and Detailed Description sections. 6, 8

2 12/05 Added lead-free notation to Ordering Information.1

3 1/07 Updated the Pin Description and Figures 5a, 9, 12. 6, 8, 10, 11, 13-16

4 3/09 Updated the Programming the Trip Voltage (VTRIP) section. 8