MAX16024LTBZ18+T - Maxim Integrated

General Description

The MAX16023/MAX16024 low-power battery-backup cir-

cuits with a regulated output are capable of delivering up

to 100mA output current. The MAX16023/MAX16024

include a low-dropout regulator, a microprocessor (µP)

reset circuit, and a battery switchover circuit. Additional

available features include a manual reset, a power-fail

comparator, and a battery-on indicator. These devices

reduce the number of external components to minimize

board space and improve reliability.

The MAX16023/MAX16024 are ideally suited for provid-

ing power for backing up critical memory such as static

random-access memory (SRAM) or real-time clocks

(RTCs). The regulated output is powered by VCC when it

is present and switches over to the backup power dur-

ing brownout. The MAX16023/MAX16024 accept an

input voltage from 1.53V to 5.5V and provide fixed stan-

dard output voltages of 1.2V, 1.8V, 2.5V, 3.0V, and 3.3V.

The MAX16024 offers the ability to externally set the out-

put voltage using a resistive divider. All outputs are

available with push-pull or open-drain configurations.

The MAX16023 offers a power-fail comparator for monitor-

ing an additional voltage or for providing an early power-

fail warning. Another feature includes a manual-reset input

(MAX16023/MAX16024). The MAX16024 also features

a battery-on indicator and chip-enable gating function.

The MAX16023/MAX16024 are offered in 8- and 10-pin

TDFN packages and are fully specified from -40°C to

+85°C temperature range.

Applications

Main/Backup Power for RTCs/SRAM

Industrial Controls

GPS Systems

Set-Top Boxes

Point-of-Sale Equipment

Portable/Battery Equipment

Features

♦System Monitoring for 5V, 3.3V, 3V, 2.5V, or 1.8V

Power-Supply Voltages

♦100mA Low-Dropout Regulator

♦Factory-Trimmed and Adjustable Output Voltages

♦1.53V to 5.5V Operating Voltage Range

♦Low-Power Consumption: 4µA (typ)

♦Power-Fail Comparators for Monitoring Voltages

Down to 0.6V

♦Battery-On Indicator

♦Battery Freshness Seal

♦On-Board Gating of CE Signals, 1.5ns

Propagation Delay (MAX16024)

♦Debounced Manual-Reset Input

♦145ms (min) Reset Timeout Period

♦Tiny 8-Pin and 10-Pin TDFN Packages

♦UL®Certified to Conform to IEC 60950-1

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

________________________________________________________________

Maxim Integrated Products

19-4249; Rev 0; 8/08

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.

Ordering Information

PART

TEMP RANGE

PIN-PACKAGE

MAX16023_TA_ _ _+T

-40°C to +85°C

8 TDFN-EP*

MAX16024_TB_ _ _+T

-40°C to +85°C

10 TDFN-EP*

The first placeholder “_” designates reset output options. A letter

“L” in this placeholder indicates a push-pull output and letter “P”

indicates an open-drain output. The next placeholder “_” desig-

nates the reset threshold (Table 1). The last two placeholders

“_ _” designate output voltage (Table 2). For the MAX16024 with

adjustable output voltage version, there are no last two place-

holders.

Denotes a lead-free/RoHS-compliant package.

T = Tape and reel.

EP = Exposed pad.

Pin Configurations

8 7 6 5

1 2 3 4

PFO

GND

*EP *EP

*EP = EXPOSED PAD

RESET

OUT

PFI

BATT

VCC

MAX16023

TDFN

10 9 8 7

1 2 3 4

GND

OUT

RESET

CEOUT

BATT

CEIN

VCC

BATT ONSET

MAX16024

TDFN

UL is a registered trademark of Underwriters Laboratories, Inc.

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC = 1.53V to 5.5V, VBATT = 3V, reset not asserted, TA= TJ= -40°C to +85°C, COUT = 10µF, unless otherwise noted. Typical val-

ues are at TA= TJ= +25°C.) (Note 2)

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, BATT, OUT to GND..........................................-0.3V to +6V

RESET, PFO, BATT ON (all open drain)

to GND..................................................................-0.3V to +6V

RESET, PFO, BATT ON (all push-pull)

to GND .................................................-0.3V to (VOUT + 0.3V)

PFI, CEIN, CEOUT to GND.......................-0.3V to (VOUT + 0.3V)

MR to GND .................................................-0.3V to (VCC + 0.3V)

Input Current

VCC Peak Current.....................................................................1A

VCC Continuous Current ...............................................250mA

BATT Peak Current .......................................................500mA

BATT Continuous Current ...............................................70mA

Output Current

OUT Short Circuit to GND Duration ....................................10s

RESET, BATT ON, CEOUT..............................................20mA

Continuous Power Dissipation (TA= +70°C)

8-Pin TDFN (derate 24.4mW/°C above +70°C) .........1951mW

10-Pin TDFN (derate 24.4mW/°C above +70°C) .......1951mW

Thermal Resistance (Note 1)

θJA (8-Pin and 10-Pin TDFN)........................................41°C/W

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°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

VBATT (Note 3) 1.53 5.5 V

LDO = 1.2V 4.3 6

LDO = 1.8V 4.7 7

LDO = 2.5V 5.2 7.5

LDO = 3V 5.5 8

VCC = LDO + 0.5V,

no load

LDO = 3.3V 5.7 8

LDO = 1.2V 16 20

LDO = 1.8V 16 21

LDO = 2.5V 16 18.1

LDO = 3V 17 18.6

Supply Current ICC

VCC = LDO + 0.5V,

IOUT = 20mA

LDO = 3.3V 17 19

µA

Supply Current in Battery-Backup

Mode IBATT VCC = 0, VBATT = 3V,

no dropout, no load 3.5 5.26 µA

BATT Standby Current VCC > VBATT + 0.2V -0.01 +0.01 µA

SET Reference Voltage VSET MAX16024_TB_, VCC = 2.2V 1.144 1.2 1.272 V

SET Input Leakage Current MAX16024_TB_, SET = 1.2V -20 +20 nA

Output Voltage Range VOUT MAX16024_TB_, VCC > VOUT 1.8 5.25 V

LDO = 1.2V 1.145 1.2 1.270

LDO = 1.8V 1.704 1.8 1.900

LDO = 2.5V 2.368 2.5 2.634

LDO = 3V 2.837 3 3.165

Output Voltage Accuracy IOUT = 1mA

LDO = 3.3V 3.114 3.3 3.482

Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-

layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

_______________________________________________________________________________________ 3

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Line Regulation VCC = (VOUT + 1V) to (VOUT + 2V),

IOUT = 1mA 0.2 1.0 %/V

Load Regulation VCC = VOUT + 1V, IOUT = 1mA to 2mA 0.15 1.0 %

LDO = 1.2V 500

LDO = 1.8V 200

LDO = 2.5V 180

LDO = 3V 150

Dropout Voltage IOUT = 50mA

(Note 4)

LDO = 3.3V 150

VCC = 1.6V 75

Output Current Limit VCC ≥ 2V 150 mA

Battery Freshness Leakage

Current VBATT = 5.5V 10 nA

RESET OUTPUT (RESET)

Reset Threshold VTH (See Table 1) V

VCC Falling to Reset Delay tRD VCC falling at 10V/ms 20 µs

Reset Timeout Period tRP VCC rising 145 215 285 ms

VOUT = 3.3V, ISINK = 3.2mA, RESET asserted 0.3

VOUT = 1.8V, ISINK = 1mA, RESET asserted 0.3RESET Output Low Voltage VOL

VOUT = 1.2V, ISINK = 100µA, RESET asserted 0.3

RESET Output High Voltage

(Push-Pull Output) VOH VCC ≥ 1.1 x VTH, ISOURCE = 100µA,

RESET deasserted VOUT - 0.3V V

RESET Output Leakage Current

(Open-Drain Output) V

RESET = 5.5V, reset deasserted 1 µA

POWER-FAIL COMPARATOR (PFI, PFO)

PFI Input Threshold VPFT VPFI falling, 1.6V ≤ VCC ≤ 5.5V 0.570 0.590 0.611 V

PFI Input Hysteresis VPFI-HYS 30 mV

PFI Input Current IPFI -1 +1 µA

VOUT = 1.8V, ISINK = 1mA, PFO asserted 0.3

PFO Output Low Voltage VOUT =1.2V, ISINK = 100µA, PFO asserted 0.3 V

PFO Output High Voltage

(Push-Pull Output) ISOURCE = 100µA, PFO deasserted VOUT - 0.3V V

PFO Leakage Current

(Open-Drain Output) V

PFO = 5.5V, PFO deasserted 1 µA

PFO Delay Time (VPFI + 100mV) to (VPFI - 100mV) 20 µs

MANUAL RESET (MR)

Input Low Voltage VIL 0.3 x VCC

Input High Voltage VIH 0.7 x VCC

Pullup Resistance Pullup resistance to VCC 20 30 kΩ

Glitch Immunity 100 ns

MR to Reset Delay 120 ns

ELECTRICAL CHARACTERISTICS (continued)

(VCC = 1.53V to 5.5V, VBATT = 3V, reset not asserted, TA= TJ= -40°C to +85°C, COUT = 10µF, unless otherwise noted. Typical val-

ues are at TA= TJ= +25°C.) (Note 2)

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(VCC = 1.53V to 5.5V, VBATT = 3V, reset not asserted, TA= TJ= -40°C to +85°C, COUT = 10µF, unless otherwise noted. Typical val-

ues are at TA= TJ= +25°C.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

BATTERY-ON INDICATOR (BATT ON)

VOUT = 1.2V, ISINK = 100µA, BATT ON

deasserted 0.3

VOUT = 1.8V, ISINK = 1mA, BATT ON

deasserted 0.3

Output Low Voltage VOL

VOUT = 3.3V, ISINK = 3.2mA, BATT ON

deasserted 0.3

Output High Voltage

(Push-Pull Output) VOH ISOURCE = 100µA, BATT ON asserted VOUT - 0.3V V

Output Leakage Current

(Open-Drain Output) VCC = 5.5V 1 µA

Output Short-Circuit Current Sink current, VCC = 5V

(Note 6) 60 mA

CE GATING (CEIN, CEOUT)

CEIN Leakage Current Reset asserted, VCC = 0.9 x VTH or 0 -1 +1 µA

CEIN to CEOUT Resistance VCC = 5V, reset deasserted 8 50 Ω

CEOUT Short-Circuit Current Reset asserted, CEOUT = 0 0.75 2 mA

CEIN to CEOUT Propagation

Delay 50Ω source, CLOAD = 50pF, VCC = 4.75V 1.5 7 ns

Output High Voltage VOH ISOURCE = 100µA, reset asserted VOUT - 0.3V V

Reset to CEOUT Delay 12 µs

Note 2: All devices are 100% production tested at TA= +25°C and TA= +85°C. Limits over temperature are guaranteed by design.

Note 3: VBATT can be 0 anytime or VCC can go down to 0 if VBATT is active (except at startup).

Note 4: Dropout voltage is defined as (VIN - VOUT) when VOUT is 2% below the value of VOUT when VIN = VOUT + 1V.

Note 5: CEIN to CEOUT resistance is tested with VCC = 5V and VCEIN = 0 or 5V.

Note 6: Use external current-limiting resistor to limit current to 20mA (max).

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

_______________________________________________________________________________________ 5

VCC SUPPLY CURRENT

vs. VCC SUPPLY VOLTAGE

MAX16023 toc01

VCC SUPPLY VOLTAGE (V)

VCC SUPPLY CURRENT (μA)

3.02.5 4.52.0 3.5 5.04.0

1.5 5.5

MAX16024PTBS25+

VOUT = 2.5V

VTH = 2.93V

VCC SUPPLY CURRENT

vs. TEMPERATURE

MAX16023 toc02

TEMPERATURE (°C)

VCC SUPPLY CURRENT (μA)

6010 35-15

-40 85

MAX16024PTBS25+

VOUT = 2.5V

VTH = 2.93V

BATT SUPPLY CURRENT

vs. VCC SUPPLY VOLTAGE

MAX16023 toc03

VCC SUPPLY VOLTAGE (V)

BATT SUPPLY CURRENT (μA)

1.0 3.00.5 2.52.01.5

0 3.5

MAX16024PTBS25+

VOUT = 2.5V

VTH = 2.93V

VBATT = 3.0V

VBATT = 2.8V

BATTERY SUPPLY CURRENT

vs. TEMPERATURE

MAX16023 toc04

TEMPERATURE (°C)

BATTERY SUPPLY CURRENT (μA)

6010 35-15

-40 85

MAX16024PTBS25+

VBATT = +3.0V

VCC = 0

BATT STANDBY CURRENT

vs. TEMPERATURE

MAX16023 toc05

TEMPERATURE (°C)

BATT STANDBY CURRENT (nA)

6010 35-15

-6

-2

-8

-4

-10

-40 85

VCC = 3.3V

VBATT = 3.0V

RESET OUTPUT VOLTAGE LOW

vs. SINK CURRENT

MAX16023 toc06

SINK CURRENT (mA)

OUTPUT VOLTAGE LOW (V)

168124

0.2

0.4

0.6

0.8

1.0

02014610218

MAX16024PTBS25+

Typical Operating Characteristics

(VCC = 5V, VBATT = 0, IOUT = 0, TA= +25°C, unless otherwise noted.)

Table 1. Reset Threshold Ranges Table 2. Fixed Output Voltage

RESET THRESHOLD RANGES (V)

SUFFIX MIN TYP MAX

L 4.508 4.63 4.906

M 4.264 4.38 4.635

T 2.991 3.08 3.239

S 2.845 2.93 3.080

R 2.549 2.63 2.755

Z 2.243 2.32 2.425

Y 2.117 2.19 2.288

W 1.603 1.67 1.733

V 1.514 1.575 1.639

SUFFIX NOMINAL OUTPUT

VOLTAGE (V)

33 3.3

30 3.0

25 2.5

18 1.8

12 1.2

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VCC = 5V, VBATT = 0, IOUT = 0, TA= +25°C, unless otherwise noted.)

VCC FALLING TO RESET DELAY

vs. TEMPERATURE

MAX16023 toc07

TEMPERATURE (°C)

DELAY (µs)

6010 35-15

100

-40 85

VCC FALLING 10V/ms

RESET TIMEOUT PERIOD

vs. TEMPERATURE

MAX16023 toc08

TEMPERATURE (°C)

RESET TIMEOUT PERIOD (ms)

6035-15 10

185

190

195

200

210

205

215

220

180

-40 85

NORMALIZED RESET THRESHOLD

vs. TEMPERATURE

MAX16023 toc09

TEMPERATURE (°C)

NORMALIZED RESET THRESHOLD

6010 35-15

0.990

1.005

1.015

1.020

0.985

0.995

1.000

1.010

0.980

-40 85

MAX16024PTBS25+

VOUT = 2.5V

MAXIMUM TRANSIENT DURATION

vs. RESET THRESHOLD OVERDRIVE

RESET THRESHOLD OVERDRIVE (mV)

TRANSIENT DURATION (ms)

MAX16023 toc10

0 200 400 600 800 1000

100

125

150

175

200

RESET OCCURS ABOVE THE CURVE

DROPOUT VOLTAGE

vs. LOAD CURRENT

MAX16023 toc11

LOAD CURRENT (mA)

DROPOUT VOLTAGE (mV)

8040 6020

150

350

450

500

100

300

200

250

400

0 1007030 5010 90

MAX16024PTBS25+

OUTPUT VOLTAGE

vs. LOAD CURRENT

MAX16023 toc12

LOAD CURRENT (mA)

OUTPUT VOLTAGE (V)

8040 6020

2.42

2.58

2.66

2.70

2.38

2.54

2.34

2.46

2.50

2.62

2.30

0 1007030 5010 90

MAX16024PTBS25+

VOUT = 2.5V

TA = -40°C

TA = +25°C

TA = +85°C

OUTPUT VOLTAGE

vs. VCC VOLTAGE

MAX16023 toc13

VCC VOLTAGE (V)

OUTPUT VOLTAGE (V)

2.1

2.5

2.7

2.8

2.0

2.4

1.9

1.8

1.7

1.6

2.2

2.3

2.6

1.5

0623 5

MAX16024PTBS25+

IOUT = 0

LOAD-TRANSIENT RESPONSE

MAX16023 toc14

1ms/div

OUT

AC-COUPLED

100mV/div

50mA

IOUT

20mA/div

10mA

MAX16024PTBS25+

COUT = 10µF

STARTUP RESPONSE

MAX16023 toc15

2ms/div

VCC

2V/div

OUT

1V/div

MAX16024PTBS25+

IOUT = 0

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

_______________________________________________________________________________________ 7

MR FALLING TO RESET DELAY

MAX16023 toc16

200ns/div

5V/div

RESET

5V/div

CHIP-ENABLE LOCKING OUT

SIGNAL DURING RESET

MAX16023 toc17

s/div

CEIN

2V/div

CEOUT

2V/div

RESET

5V/div

Typical Operating Characteristics (continued)

(VCC = 5V, VBATT = 0, IOUT = 0, TA= +25°C, unless otherwise noted.)

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

8 _______________________________________________________________________________________

Pin Description

MAX16023 MAX16024 NAME FUNCTION

12V

CC Supply Voltage Input. Bypass VCC to GND with a 0.1µF capacitor.

2 3 BATT

Backup Battery Input. If VCC falls below its reset threshold (VTH), VBATT ≥ VCC, and if

the regulator enters dropout, the regulator is powered from BATT. If VBATT < VCC,

the regulator is powered from VCC. Bypass BATT to GND with a 0.1µF capacitor.

34MR

Active-Low, Manual-Reset Input. RESET asserts when MR is pulled low. RESET

remains low for the duration of reset timeout period after MR transitions from low to

high. Connect MR to OUT or leave unconnected if not used. MR is internally

connected to VCC through a 30kΩ pullup resistor.

4 — PFI

Power-Fail Comparator Input. Connect PFI to a resistive divider to set the desired PFI

threshold. The PFI input is referenced to an internal VPFT threshold. A VPFI-HYS

internal hysteresis provides noise immunity. The power-fail comparator is powered

from OUT.

5—PFO

Active-Low, Power-Fail Comparator Output. PFO goes low when VPFI falls below the

internal VPFT threshold and goes high when VPFI rises above VPFT + VPFI-HYS

hysteresis.

6 7 GND Ground

78RESET

Active-Low Reset Output. RESET asserts when VCC falls below the reset threshold or

MR is pulled low. RESET remains low for the duration of the reset timeout period after

VCC rises above the reset threshold and MR goes high. RESET is available in push-

pull and open-drain options.

8 9 OUT

Linear Regulator Output Voltage. Available in the following factory-fixed voltages of

1.2V, 1.8V, 2.5V, 3.0V, or 3.3V for all devices. The MAX16024 is also available with

an adjustable output voltage (1.8V to 5.25V). Bypass OUT to GND with a 10µF

capacitor.

—1CEIN Chip-Enable Input. The input to CE gating circuitry. Connect to GND or OUT if not

used.

— 5 SET

Set Output Voltage Input. For the fixed output voltage versions (MAX16024_TB_ _ _),

SET is not used. Connect SET to GND. For MAX16024_TB_, connect SET to an

external resistive divider to set the desired output voltage between 1.8V and 5.25V.

— 6 BATT ON Active-High, Battery-On Output. BATT ON goes high when in the battery backup

mode.

—10CEOUT

Active-Low, Chip-Enable Output. CEOUT goes low only when CEIN is low and reset

is not asserted. If CEIN is low when reset is asserted, CEOUT stays low for 12µs (typ)

or until CEIN goes high, whichever occurs first.

——EP

Exposed Pad. Internally connected to GND. Connect EP to a large ground plane to

aid heat dissipation. Do not use EP as the only ground connection for the device.

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

_______________________________________________________________________________________ 9

Functional Diagrams

MAX16023

PFI

PFO

OUT

GND

VCC

RESET DELAY

LOGIC

LDO

REF

OUT

RESET

BATT

DROPOUT

OUT

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

10 ______________________________________________________________________________________

Functional Diagrams (continued)

MAX16024

CEIN CEOUT

GND

VCC

RESET DELAY

LOGIC

LDO

REF

VCC

CE OUTPUT

CONTROL

BATT

DROPOUT

OUT

SET

RESET

BATT ON

Detailed Description

The

Typical Applications Circuit

shows a typical con-

nection using the MAX16024. OUT powers the SRAM. If

VCC is higher than the reset threshold (VTH), or if VCC is

lower than VTH but higher than VBATT, the regulator is

powered from VCC. If VCC < VTH, VCC < VBATT, and the

regulator is in dropout, the regulator is powered from

BATT (see the

Functional Diagrams

). OUT supplies up

to 100mA from VCC.

Backup-Battery Switchover

In a brownout or power failure, it may be necessary to

preserve the contents of the RAM. With a backup-bat-

tery installed at BATT, the MAX16023/MAX16024 auto-

matically switch the RAM to backup power when VCC

falls. The MAX16024 has a BATT ON output that goes

high when in battery-backup mode. Three conditions

must be met for these devices to switch to battery

backup mode:

1) VCC is lower than the reset threshold.

2) VCC is lower than VBATT.

3) The regulator is in dropout (except for the 1.2V out-

put version).

Chip-Enable Signal Gating (MAX16024)

The MAX16024 provides internal gating of CE signals to

prevent erroneous data from being written to CMOS

RAM in the event of a power failure or brownout. During

normal operation, the CE gate enables and passes all

CE transitions. When the reset output asserts, this path

becomes disabled, preventing erroneous data from cor-

rupting the CMOS RAM and CEOUT is pulled up to OUT

through an internal current source. The 1.5ns propaga-

tion delay from CEIN to CEOUT allows the devices to

be used with most µPs and high-speed DSPs.

During normal operation (reset not asserted), CEIN is

connected to CEOUT through a low on-resistance

transmission gate. If CEIN is high when a reset asserts,

CEOUT remains high regardless of any subsequent

transition on CEIN during the reset event.

If CEIN is low when reset asserts, CEOUT is held low for

12µs to allow completion of the read/write operation.

After the 12µs delay expires, CEOUT goes high and

stays high regardless of any subsequent transitions on

CEIN during the reset event. When CEOUT is discon-

nected from CEIN, CEOUT is actively pulled up to OUT.

The propagation delay through the chip-enable circuitry

depends on both the source impedance of the drive to

CEIN and the capacitive loading at CEOUT. Minimize

the capacitive load at CEOUT to minimize propagation

delay, and use a low-output-impedance driver.

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

______________________________________________________________________________________ 11

VCC

RESET THRESHOLD VTH

CEIN

CEOUT

RESET

tRD tRD

tRP tRP

IF CEIN GOES HIGH BEFORE RESET ASSERTS,

CEOUT GOES HIGH WITHOUT DELAY AS

CEIN GOES HIGH.

RESET-TO-CEOUT DELAY (12µs)

Figure 1. Reset and Chip-Enable Timing

MAX16023/MAX16024

Manual-Reset Input

(MAX16023/MAX16024)

Many µP-based products require manual-reset capabili-

ty, allowing the operator, a test technician, or external

logic circuitry to initiate a reset. For the MAX16023/

MAX16024, a logic-low on MR asserts RESET. RESET

remains asserted while MR is low. When MR goes high,

RESET deasserts after a minimum of 145ms (tRP). MR

has an internal 30kΩpullup resistor to VCC. MR can be

driven with TTL/CMOS logic levels or with open-

drain/collector outputs. Connect a normally open

momentary switch from MR to GND to create a manual-

reset function; external debounce circuitry is not

required. If MR is driven from a long cable or the device

is used in a noisy environment, connect a 0.1µF capaci-

tor from MR to GND to provide additional noise immunity.

Battery-On Indicator (MAX16024)

The MAX16024’s BATT ON output goes high when in

battery-backup mode. Use BATT ON to indicate bat-

tery-switchover status.

Battery Freshness Seal

The MAX16023/MAX16024 battery freshness seal dis-

connects the backup battery from internal circuitry and

OUT until VCC is applied. This ensures the backup bat-

tery connected to BATT is fresh when the final product

is used for the first time.

The internal freshness seal latch prevents BATT from

powering OUT until VCC has come up for the first time,

setting the latch. When VCC subsequently turns off,

BATT begins to power OUT.

To reenable the freshness seal (MAX16023/

MAX16024):

1) Connect a battery to BATT.

2) Bring VCC to 0.

3) Drive MR higher than VBATT + 1.2V for at least 3µs.

4) Pull OUT to 0.

Reset Output (MAX16023/MAX16024)

A µP’s reset input starts the µP in a known state. The

MAX16023/MAX16024 µP supervisory circuits assert a

reset to prevent code-execution errors during power-

up, power-down, and brownout conditions. RESET

asserts when VCC is below the reset threshold and

remains low for at least 145ms (tRP) after VCC rises

above the reset threshold. RESET also asserts when

MR is low. RESET is available in both push-pull and

open-drain configurations.

Power-Fail Comparator (MAX16023)

The MAX16023 offers an additional undervoltage com-

parator. The output PFO goes low when the voltage at

PFI falls below its VPFT threshold. Common uses for the

power-fail comparator include monitoring the input of the

power supply (such as a battery) before any voltage reg-

ulation to provide an early power-fail warning, so soft-

ware can conduct an orderly system shutdown. The

power-fail comparator has a typical input hysteresis of

VPFI-HYS and is powered from OUT, making it indepen-

dent of the reset circuit. Connect PFI to GND, if not used.

Regulator Output

Fixed output voltages of 1.2V, 1.8V, 2.5V, 3.0V, and

3.3V are available for all devices. The regulator output

delivers up to 100mA of load current.

The MAX16024 is available with both fixed and

adjustable output-voltage options. Use an external

resistive divider network connected between OUT, SET,

and GND (Figure 2) to set the adjustable output voltage

from 1.8V to 5.25V. Connect SET to GND for parts with

fixed output voltage option.

Battery-Backup Circuits with

Regulated Output Voltage

12 ______________________________________________________________________________________

MAX16024

0.1µF

1.53 TO 5.5V

GND

VCC

RESETTO µP

SET

10µF

1.8V TO 5.25V

VOUT = VSET (1 + R1/R2)

VSET = 1.2V

OUT

Figure 2. Setting the Adjustable Output Voltage (MAX16024

Only)

Applications Information

The MAX16023/MAX16024 are protected for typical

short-circuit conditions of 10s or less. Shorting OUT to

ground for longer than 10s might damage the device.

Bypass VCC and BATT to GND with a 0.1µF capacitor

each. Connect a 10µF low-ESR capacitor from OUT to

GND. All capacitors should be mounted as close as

possible to the device.

Monitoring an Additional Supply

The MAX16023 power-fail comparator can monitor

either positive or negative supplies using a resistive

divider to PFI (Figures 3 and 4). PFO can be used to

generate an interrupt to the µP or to trigger a reset. To

monitor a negative supply, connect the top of the resis-

tive divider to VCC. Connect the bottom of the resistive

divider to the negative voltage to be monitored.

Adding Hysteresis to PFI

The power-fail comparators have a typical input hys-

teresis of VPFI-HYS. This is sufficient for most applica-

tions where a power-supply line is being monitored

through an external voltage-divider (see the

Monitoring

an Additional Supply

section). Figure 5 shows how to

add hysteresis to the power-fail comparator. Select the

ratio of R1 and R2 such that PFI sees VPFT when VIN

falls to the desired trip point (VTRIP). Resistor R3 adds

hysteresis. R3 is typically an order of magnitude greater

than R1 or R2. The current through R1 and R2 should

be at least 100µA to ensure that the 1µA (max) PFI

input current does not shift the trip point. R3 should be

larger than 50kΩto prevent it from loading down PFO.

Capacitor C1 adds additional noise rejection.

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

______________________________________________________________________________________ 13

MAX16023L

0.1µF

GND

PFI

PFO

ADDITIONAL SUPPLY RESET VOLTAGE

RESET

VCC

RESET

µP

V2(RESET) = VPFT x ( )

R1 + R2

Figure 3. Monitoring an Additional Supply by Connecting PFO

to MR

MAX16023

0.1μF

GND

PFI

PFO

VCC

VTRIP = VPFT - (5 - VPFT)

VTRIP IS NEGATIVE

V-

PFO 0

+5V

VTRIP V-

Figure 4. Monitoring a Negative Supply

MAX16023/MAX16024

Operation Without a Backup

Power Source

The MAX16023/MAX16024 provide battery-backup

functions. If a backup power source is not used, con-

nect BATT to GND.

Replacing the Backup Battery

When VCC is above VTH, the backup power source can

be removed without danger of triggering a reset pulse.

The device does not enter battery-backup mode when

VCC stays above the reset threshold voltage.

Negative-Going VCC Transients

The MAX16023/MAX16024 are relatively immune to

short duration, negative-going VCC transients.

Resetting the µP when VCC experiences only small

glitches is usually not desirable. A 0.1µF bypass

capacitor mounted close to the VCC pin provides addi-

tional transient immunity.

Capacitor Selection and

Regulator Stability

For stable operation, connect a low-ESR 10µF (min) out-

put capacitor from OUT to GND. To reduce noise and

improve load-transient response and power-supply rejec-

tion, use larger output capacitor values.

Battery-Backup Circuits with

Regulated Output Voltage

14 ______________________________________________________________________________________

MAX16023

0.1µF

GND

PFI

PFO

VCC

VH = (VPFT + VPFI - HYS)

x ( + + 1)

VL = R1 x ( - ) + VPFT

VPFT

VCC - VPFT

WHERE VPFT IS THE POWER-FAIL

THRESHOLD VOLTAGE.

*OPTIONAL

+5V

VIN

C1*

TO µP

PFO 0

+5V

VTRIP

VLVHVIN

VTRIP = VPFT x ( )

R1 + R2

Figure 5. Adding Hysteresis to the Power-Fail Comparator

Part Number Table

PART OUTPUT

TYPE

R ESET

T H R ESH O L D

VO L T A G E

( V)

REGUL ATED

OU TPU T

VO LTA GE

( V)

PART OUTPUT

TYPE

R ESET

T H R ESH O L D

VO L T A G E

( V)

R EG U L A T ED

O U T PU T

VO L T A G E

( V)

MAX16023LTAL12+T Push-Pull 4.63 1.2 MAX16024LTBL12+T Push-Pull 4.63 1.2

MAX16023LTAL18+T Push-Pull 4.63 1.8 MAX16024LTBL18+T Push-Pull 4.63 1.8

MAX16023LTAL25+T Push-Pull 4.63 2.5 MAX16024LTBL25+T Push-Pull 4.63 2.5

MAX16023LTAL33+T Push-Pull 4.63 3.3 MAX16024LTBL33+T Push-Pull 4.63 3.3

MAX16023LTAM12+T Push-Pull 4.38 1.2 MAX16024LTBM12+T Push-Pull 4.38 1.2

MAX16023LTAM18+T Push-Pull 4.38 1.8 MAX16024LTBM18+T Push-Pull 4.38 1.8

MAX16023LTAM25+T Push-Pull 4.38 2.5 MAX16024LTBM25+T Push-Pull 4.38 2.5

MAX16023LTAM33+T Push-Pull 4.38 3.3 MAX16024LTBM33+T Push-Pull 4.38 3.3

MAX16023LTAT12+T Push-Pull 3.08 1.2 MAX16024LTBT12+T Push-Pull 3.08 1.2

MAX16023LTAT18+T Push-Pull 3.08 1.8 MAX16024LTBT18+T Push-Pull 3.08 1.8

MAX16023LTAT25+T Push-Pull 3.08 2.5 MAX16024LTBT25+T Push-Pull 3.08 2.5

MAX16023LTAS12+T Push-Pull 2.93 1.2 MAX16024LTBS12+T Push-Pull 2.93 1.2

MAX16023LTAS18+T Push-Pull 2.93 1.8 MAX16024LTBS18+T Push-Pull 2.93 1.8

MAX16023LTAS25+T Push-Pull 2.93 2.5 MAX16024LTBS25+T Push-Pull 2.93 2.5

MAX16023LTAR12+T Push-Pull 2.63 1.2 MAX16024LTBR12+T Push-Pull 2.63 1.2

MAX16023LTAR18+T Push-Pull 2.63 1.8 MAX16024LTBR18+T Push-Pull 2.63 1.8

MAX16023LTAR25+T Push-Pull 2.63 2.5 MAX16024LTBR25+T Push-Pull 2.63 2.5

MAX16023LTAZ12+T Push-Pull 2.32 1.2 MAX16024LTBZ12+T Push-Pull 2.32 1.2

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

______________________________________________________________________________________ 15

Part Number Table (continued)

PART OUTPUT

TYPE

R ESET

T H R ESH O L D

VO L T A G E

( V)

REGUL ATED

OU TPU T

VO LTA GE

( V)

PART OUTPUT

TYPE

R ESET

T H R ESH O L D

VO L T A G E

( V)

R EG U L A T ED

O U T PU T

VO L T A G E

( V)

MAX16023LTAZ18+T Push-Pull 2.32 1.8 MAX16024LTBZ18+T Push-Pull 2.32 1.8

MAX16023LTAY12+T Push-Pull 2.19 1.2 MAX16024LTBY12+T Push-Pull 2.19 1.2

MAX16023LTAY18+T Push-Pull 2.19 1.8 MAX16024LTBY18+T Push-Pull 2.19 1.8

MAX16023LTAW12+T Push-Pull 1.67 1.2 MAX16024LTBW12+T Push-Pull 1.67 1.2

MAX16023LTAV12+T Push-Pull 1.575 1.2 MAX16024LTBV12+T Push-Pull 1.575 1.2

MAX16023PTAL12+T Open-Drain 4.63 1.2 MAX16024PTBL12+T Open-Drain 4.63 1.2

MAX16023PTAL18+T Open-Drain 4.63 1.8 MAX16024PTBL18+T Open-Drain 4.63 1.8

MAX16023PTAL25+T Open-Drain 4.63 2.5 MAX16024PTBL25+T Open-Drain 4.63 2.5

MAX16023PTAL33+T Open-Drain 4.63 3.3 MAX16024PTBL33+T Open-Drain 4.63 3.3

MAX16023PTAM12+T Open-Drain 4.38 1.2 MAX16024PTBM12+T Open-Drain 4.38 1.2

MAX16023PTAM18+T Open-Drain 4.38 1.8 MAX16024PTBM18+T Open-Drain 4.38 1.8

MAX16023PTAM25+T Open-Drain 4.38 2.5 MAX16024PTBM25+T Open-Drain 4.38 2.5

MAX16023PTAM33+T Open-Drain 4.38 3.3 MAX16024PTBM33+T Open-Drain 4.38 3.3

MAX16023PTAT12+T Open-Drain 3.08 1.2 MAX16024PTBS12+T Open-Drain 3.08 1.2

MAX16023PTAT18+T Open-Drain 3.08 1.8 MAX16024PTBS18+T Open-Drain 3.08 1.8

MAX16023PTAT25+T Open-Drain 3.08 2.5 MAX16024PTBS25+T O p e n - D r a i n 3.08 2.5

MAX16023PTAS12+T Open-Drain 2.93 1.2 MAX16024PTBT12+T Open-Drain 2.93 1.2

MAX16023PTAS18+T Open-Drain 2.93 1.8 MAX16024PTBT18+T Open-Drain 2.93 1.8

MAX16023PTAS25+T Open-Drain 2.93 2.5 MAX16024PTBT25+T Open-Drain 2.93 2.5

MAX16023PTAR12+T Open-Drain 2.63 1.2 MAX16024PTBR12+T Open-Drain 2.63 1.2

MAX16023PTAR18+T Open-Drain 2.63 1.8 MAX16024PTBR18+T Open-Drain 2.63 1.8

MAX16023PTAR25+T Open-Drain 2.63 2.5 MAX16024PTBR25+T Open-Drain 2.63 2.5

MAX16023PTAZ12+T Open-Drain 2.32 1.2 MAX16024PTBZ12+T Open-Drain 2.32 1.2

MAX16023PTAZ18+T Open-Drain 2.32 1.8 MAX16024PTBZ18+T Open-Drain 2.32 1.8

MAX16023PTAY12+T Open-Drain 2.19 1.2 MAX16024PTBY12+T Open-Drain 2.19 1.2

MAX16023PTAY18+T Open-Drain 2.19 1.8 MAX16024PTBY18+T Open-Drain 2.19 1.8

MAX16023PTAW12+T Open-Drain 1.67 1.2 MAX16024PTBW12+T Open-Drain 1.67 1.2

MAX16023PTAV12+T Open-Drain 1.575 1.2 MAX16024PTBV12+T Open-Drain 1.575 1.2

MAX16024PTBL+T Open-Drain 4.63 Adjustable MAX16024LTBL+T Push-Pull 4.63 Adjustable

MAX16024PTBM+T Open-Drain 4.38 Adjustable MAX16024LTBM+T Push-Pull 4.38 Adjustable

MAX16024PTBT+T Open-Drain 3.08 Adjustable MAX16024LTBT+T Push-Pull 3.08 Adjustable

MAX16024PTBS+T Open-Drain 2.93 Adjustable MAX16024LTBS+T Push-Pull 2.93 Adjustable

MAX16024PTBR+T Open-Drain 2.63 Adjustable MAX16024LTBR+T Push-Pull 2.63 Adjustable

MAX16024PTBZ+T Open-Drain 2.32 Adjustable MAX16024LTBZ+T Push-Pull 2.32 Adjustable

MAX16024PTBY+T Open-Drain 2.19 Adjustable MAX16024LTBY+T Push-Pull 2.19 Adjustable

MAX16024PTBW+T Open-Drain 1.67 Adjustable MAX16024LTBW+T Push-Pull 1.67 Adjustable

MAX16024PTBV+T Open-Drain 1.575 Adjustable MAX16024LTBV+T Push-Pull 1.575 Adjustable

Bold parts denote standard versions. Samples are generally available on standard versions.

Contact factory for availability of nonstandard versions.

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

16 ______________________________________________________________________________________

Typical Applications Circuit

MAX16024L

0.1µF

0.1µF0.1µF

10µF

BATT

GND

SET

PUSHBUTTON

CEIN

CEOUT

BATT ON

OUT

RESET

ADDRESS

DECODE

RTC

RAM

VCC

µP

RST

A0–A15

3.3V

VCC

PART

OUTPUTS

(RESET, PFO,

BATT ON )

RESET MR POWER-FAIL

COMPARATOR

GATE BATT ON REGULATOR

OUTPUT VOLTAGE

MAX16023L Push-Pull √√ √ — — Fixed

MAX16023P Open Drain √√ √ — — Fixed

MAX16024L Push-Pull √√ —√√Fixed/adjustable

MAX16024P Open Drain √√ —√√Fixed/adjustable

Selector Guide

MAX16023/MAX16024

Battery-Backup Circuits with

Regulated Output Voltage

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 ____________________

Package Information

For the latest package outline information and land patterns, go

to www.maxim-ic.com/packages.

PACKAGE TYPE PACKAGE CODE DOCUMENT NO.

8 TDFN T833-2 21-0137

10 TDFN T1033-1 21-0137

Chip Information

PROCESS: BiCMOS

Mouser Electronics

Authorized Distributor

Click to View Pricing, Inventory, Delivery & Lifecycle Information:

Maxim Integrated:

MAX16023LTAL12+T MAX16023LTAL18+T MAX16023LTAL25+T MAX16023LTAL33+T MAX16023LTAM12+T

MAX16023LTAM18+T MAX16023LTAM25+T MAX16023LTAM33+T MAX16023LTAR12+T MAX16023LTAR18+T

MAX16023LTAR25+T MAX16023LTAS12+T MAX16023LTAS18+T MAX16023LTAS25+T MAX16023LTAT12+T

MAX16023LTAT18+T MAX16023LTAT25+T MAX16023LTAV12+T MAX16023LTAW12+T MAX16023LTAY12+T

MAX16023LTAY18+T MAX16023LTAZ12+T MAX16023LTAZ18+T MAX16023PTAL12+T MAX16023PTAL18+T

MAX16023PTAL25+T MAX16023PTAL33+T MAX16023PTAM12+T MAX16023PTAM18+T MAX16023PTAM25+T

MAX16023PTAM33+T MAX16023PTAR12+T MAX16023PTAR18+T MAX16023PTAR25+T MAX16023PTAS12+T

MAX16023PTAS18+T MAX16023PTAS25+T MAX16023PTAT12+T MAX16023PTAT18+T MAX16023PTAT25+T

MAX16023PTAV12+T MAX16023PTAW12+T MAX16023PTAY12+T MAX16023PTAY18+T MAX16023PTAZ12+T

MAX16023PTAZ18+T MAX16024LTBL+T MAX16024LTBL12+T MAX16024LTBL18+T MAX16024LTBL25+T

MAX16024LTBL33+T MAX16024LTBM+T MAX16024LTBM12+T MAX16024LTBM18+T MAX16024LTBM25+T

MAX16024LTBM33+T MAX16024LTBR+T MAX16024LTBR12+T MAX16024LTBR18+T MAX16024LTBR25+T

MAX16024LTBS+T MAX16024LTBS12+T MAX16024LTBS18+T MAX16024LTBS25+T MAX16024LTBT+T

MAX16024LTBT12+T MAX16024LTBT18+T MAX16024LTBT25+T MAX16024LTBV+T MAX16024LTBV12+T

MAX16024LTBW+T MAX16024LTBW12+T MAX16024LTBY+T MAX16024LTBY12+T MAX16024LTBY18+T

MAX16024LTBZ+T MAX16024LTBZ12+T MAX16024LTBZ18+T MAX16024PTBL+T MAX16024PTBL12+T

MAX16024PTBL18+T MAX16024PTBL25+T MAX16024PTBL33+T MAX16024PTBM+T MAX16024PTBM12+T

MAX16024PTBM18+T MAX16024PTBM25+T MAX16024PTBM33+T MAX16024PTBR+T MAX16024PTBR12+T

MAX16024PTBR18+T MAX16024PTBR25+T MAX16024PTBS+T MAX16024PTBS12+T MAX16024PTBS18+T

MAX16024PTBS25+T MAX16024PTBT+T MAX16024PTBT12+T MAX16024PTBT18+T MAX16024PTBT25+T