Rainbow Electronics MAX6781 User Manual

General Description

The MAX6775–MAX6781 low-power, 1%-accurate battery monitors are available in the ultra-small µDFN package (1.0mm x 1.5mm) and SC70 packages. These low-power devices are ideal for monitoring single lithium-ion (Li+) cells, or multicell alkaline/NiCd/NiMH power sources. These devices offer single (MAX6775/ MAX6776/MAX6777/MAX6778) or dual (MAX6779/ MAX6780/MAX6781) low-battery outputs and feature fixed or resistor-adjustable hysteresis. Hysteresis eliminates the output chatter sometimes associated with battery voltage monitors, usually due to input-voltage noise or battery terminal voltage recovery after load removal.

These devices are available in several versions: with single- or dual-voltage monitors, and with fixed or adjustable hysteresis. The MAX6775/MAX6776 offer a single battery monitor and factory-set hysteresis of

0.5%, 5%, or 10%. The MAX6779/MAX6780/MAX6781 have two battery monitors in a single package and factory-set hysteresis of 0.5%, 5%, or 10%. The MAX6777/ MAX6778 offer a single battery monitor with external inputs for the rising and falling thresholds, allowing external hysteresis control.

For convenient interface with system power circuitry or microprocessors, both open-drain and push-pull outputs are available. The single-channel devices are available with open-drain or push-pull outputs. The dual-channel devices are available with both outputs open-drain, both outputs push-pull, or one of each (see the Selector Guide). This family of devices is offered in small 5-pin SC70 and ultra-small 6-pin µDFN packages, and is fully specified over the -40°C to +85°C extended temperature range.

Applications

Battery-Powered Systems (Single-Cell Li+ or Multicell NiMH, NiCd, Alkaline)

Cell Phones/Cordless Phones

Pagers

Portable Medical Devices

PDAs

Electronic Toys

MP3 Players

Features

♦ 1.0%-Accurate Threshold Specified Over

Temperature

♦ Single/Dual, Low-Battery Output Options

♦ Low 3µA Battery Current

♦ Open-Drain or Push-Pull Low-Battery Outputs

♦ Fixed or Adjustable Hysteresis

♦ Low-Input Leakage Current Allows Use of Large

Resistors

♦ Guaranteed Valid Low-Battery-Output Logic State

Down to V

BATT

= 1V

♦ Immune to Short Battery Transients

♦ Fully Specified from -40°C to +85°C

♦ Small 5-Pin SC70 or Ultra-Small 6-Pin µDFN

(1mm x 1.5mm) Package

MAX6775–MAX6781

Low-Power, 1%-Accurate Battery

Monitor in µDFN and SC70 Packages

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

LBI

3.6V

LBO

BATT

MAX6775

SHDN OUT

DC-DC

CONVERTER

Typical Operating Circuit

19-3774; Rev 0; 8/05

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.

Ordering Information continued at end of data sheet.

+Denotes lead-free package.

*Future product—contact factory for availability. MAX6775/MAX6776/MAX6779/MAX6780/MAX6781 are available with factory-trimmed hysteresis. Specify trim by replacing “_” with “A” for 0.5%, “B” for 5%, or “C” for 10% hysteresis.

Pin Configurations appear at end of data sheet.

PART TEMP RANGE PIN-PACKAGE

MAX6775XK_+T -40°C to +85°C 5 SC70-5

MAX6775LT_+T* -40°C to +85°C 6 µDFN-6

MAX6776XK_+T* -40°C to +85°C 5 SC70-5

MAX6776LT_+T* -40°C to +85°C 6 µDFN-6

MAX6777XK+T -40°C to +85°C 5 SC70-5

MAX6777LT+T* -40°C to +85°C 6 µDFN-6

MAX6775–MAX6781

Low-Power, 1%-Accurate Battery Monitor in µDFN and SC70 Packages

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

BATT

= 1.6V to 5.5V, TA= -40°C to +85°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.

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

LBI, LBL, LBH, LBI1, LBI2 to GND ...............-0.3V to minimum of

((V

BATT

+ 0.3V) and +6V)

LBO, LBO1, LBO2 to GND (open-drain) .................-0.3V to +6V

LBO, LBO1, LBO2 to GND (push-pull).........-0.3V to minimum of

((V

BATT

+ 0.3V) and +6V)

Input Current (all pins) ........................................................20mA

Output Current (all pins) .....................................................20mA

Continuous Power Dissipation (T

= +70°C)

5-Pin SC70 (derate 3.1mW/°C above +70°C)..............247mW

6-Pin µDFN (derate 2.1mW°C above +70°C) ..............168mW

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

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

PARAMETER

CONDITIONS MIN TYP MAX

UNITS

TA = 0°C to +70°C 1.0 5.5

Operating Voltage Range (Note 2)

TA = -40°C to +85°C 1.2 5.5

BATT

= 3.7V, no load 4 7

Supply Current I

BATT

= 1.8V, no load 3.2 6

µA

FIXED HYSTERESIS (MAX6775/MAX6776/MAX6779/MAX6780/MAX6781)

0.5% hysteresis version

5% hysteresis version

LBI, LBI_ Falling Threshold (Note 3)

LBIF

10% hysteresis version

LBI Rising Threshold V

LBIR

1.222

LBI Input Leakage Current 0.2V ≤ V

LBI

≤ V

BATT

- 0.2V -5 +5 nA

ADJUSTABLE HYSTERESIS (MAX6777/MAX6778)

LBL, LBH Threshold V

BATT

= 1.8V to 5.5V

1.222

LBL, LBH Input Leakage Current

BATT

- 0.2V ≥ V

LBL/LBH

≥ 0.2V -5 +5 nA

SYMBOL

BATT

1.2037 1.2159 1.2280

1.1493 1.1609 1.1725

1.0888 1.0998 1.1108

1.2098

1.2342

MAX6775–MAX6781

Low-Power, 1%-Accurate Battery

Monitor in µDFN and SC70 Packages

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

BATT

= 1.6V to 5.5V, TA= -40°C to +85°C, unless otherwise specified. Typical values are at TA= +25°C.) (Note 1)

Note 1: Devices are tested at T

= +25°C and guaranteed by design for TA=T

MIN

to T

MAX

, as specified.

Note 2: Operating range ensures low-battery output is in the correct state. Minimum battery voltage for electrical specification is 1.6V. Note 3: The rising threshold is guaranteed to be higher than the falling threshold.

PARAMETER

SYMBOL

CONDITIONS MIN TYP MAX

UNITS

LOW-BATTERY OUTPUTS (LBO, LBO1, LBO2)

Propagation Delay t

LBI_

+ 100mV to V

LBI_

- 100mV 9 µs

Startup Time V

BATT

rising above 1.6V 3 ms

BATT

≥ 1.2V, I

SINK

= 100µA 0.3

BATT

≥ 2.7V, I

SINK

= 1.2mA 0.3

Output Low (Push-Pull or Open-Drain)

BATT

≥ 4.5V, I

SINK

= 3.2mA 0.3

BATT

≥ 1.6V, I

SOURCE

= 100µA

0.8 x

BATT

≥ 2.7V, I

SOURCE

= 500µA

0.8 x

Output High (Push-Pull ) V

BATT

≥ 4.5V, I

SOURCE

= 800µA

0.8 x

Output Leakage Current (Open-Drain)

Output not asserted, V

LBO_

= 5.5V -100 +100 nA

Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

SUPPLY CURRENT

vs. TEMPERATURE

MAX6775 toc01

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

603510-15

3.0

3.5

4.0

4.5

5.0

5.5

6.0

2.5

-40 85

BATT

= 5V

BATT

= 3.6V

BATT

= 3V

BATT

= 2.4V

BATT

= 1.6V

PROPAGATION DELAY

vs. TEMPERATURE

MAX6775 toc02

TEMPERATURE (°C)

PROPAGATION DELAY (µs)

603510-15

-40 85

BATT

= 5V

100mV OVERDRIVE

BATT

= 1.6V

MAXIMUM TRANSIENT DURATION

vs. THRESHOLD OVERDRIVE

MAX6775 toc03

THRESHOLD OVERDRIVE VTH - VCC (mV)

MAXIMUM TRANSIENT DURATION (µs)

10010

1 1000

OUTPUT ASSERTED ABOVE THIS LINE

BATT

MAX6775–MAX6781

Low-Power, 1%-Accurate Battery Monitor in µDFN and SC70 Packages

4 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(TA = +25°C, unless otherwise noted.)

NORMALIZED THRESHOLD VOLTAGES

vs. TEMPERATURE, MAX67__A

MAX6775 toc04

TEMPERATURE (°C)

THRESHOLD VOLTAGE (mV)

603510-15

-4

-3

-2

-1

-5

-40 85

NORMALIZED AT TA = +25°C

RISING

FALLING

NORMALIZED THRESHOLD VOLTAGES

vs. TEMPERATURE, MAX67__B

MAX6775 toc05

TEMPERATURE (°C)

THRESHOLD VOLTAGE (mV)

603510-15

-3

-2

-1

-4

-40 85

NORMALIZED AT TA = +25°C

RISING

FALLING

NORMALIZED THRESHOLD VOLTAGES

vs. TEMPERATURE, MAX67__C

MAX6775 toc06

TEMPERATURE (°C)

THRESHOLD VOLTAGE (mV)

603510-15

-2

-1

-3

-40 85

NORMALIZED AT TA = +25°C

RISING

FALLING

LBO OUTPUT VOLTAGE

vs. SINK CURRENT

MAX6775 toc07

SINK CURRENT (mA)

OUTPUT VOLTAGE (V)

12963

0.1

0.2

0.3

0.4

0.5

015

BATT

= 5.0V

BATT

= 1.8V

BATT

= 3.3V

LBO OUTPUT VOLTAGE vs. SOURCE CURRENT

MAX6775 toc08

SOURCE CURRENT (mA)

OUTPUT VOLTAGE (V)

4321

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

1.0 05

BATT

= 5.0V

BATT

= 3.3V

BATT

= 1.8V

MAX6775–MAX6781

Low-Power, 1%-Accurate Battery

Monitor in µDFN and SC70 Packages

_______________________________________________________________________________________ 5

Pin Description

MAX6775/

MAX6776

MAX6777/

MAX6778

MAX6779/

µDFN

NAME FUNCTION

11—— — GND2

Reserved. Must be connected to GND. Do not use as the only GND connection.

2222 2 GND Ground

33—— — LBI

Low-Battery Input. Connect to the resistive divider to set the trip level.

4444 — LBO

Low-Battery Output, Active-Low. When V

LBI/VLBL

falls below

the falling threshold, LBO asserts. LBO deasserts when V

LBI/VLBH

exceeds the rising threshold voltage.

5—5— — N.C. No Connection. Not internally connected.

6565 6 BATT Battery Input. Power supply to the device.

——1 1 — LBH

Rising-Trip-Level Input. Connect to a resistive divider to set the rising trip level.

——3 3 — LBL

Falling-Trip-Level Input. Connect to a resistive divider to set the falling trip level.

———— 1 LBI2

Low-Battery Input 2. Connect to a resistive divider to set the trip level.

———— 3 LBI1

Low-Battery Input 1. Connect to a resistive divider to set the trip level.

———— 4 LBO1

Low-Battery Output 1, Active-Low. When V

LBI1

falls below the

falling threshold voltage, LBO1 asserts. LBO1 deasserts when V

LBI1

exceeds the rising threshold voltage. LBO1 is push-pull

on the MAX6781 and open-drain for the MAX6779/MAX6780.

———— 5 LBO2

Low-Battery Output 2, Active-Low. When V

LBI2

falls below the

falling threshold voltage, LBO2 asserts. LBO2 deasserts when

LBI2

exceeds the rising threshold voltage. LBO2 is open-drain.

SC70 µDFN SC70

MAX6780/

MAX6781

MAX6775–MAX6781

Detailed Description

These battery monitors have an active-low output that asserts when the input falls below a set voltage. They also offer hysteresis for noise immunity, and to remove the possibility of output chatter due to battery terminal voltage recovery after load removal. They are available with one or two monitors per package, with push-pull or open-drain outputs, and with internally set or externally adjustable hysteresis (dual-channel devices offer only internally fixed hysteresis). Figures 1, 2, and 3 show block diagrams and typical connections. See the Selector Guide for details.

Low-Battery Output

All devices are offered with either push-pull or opendrain outputs (see the Selector Guide). The MAX6781 has one push-pull output and one open-drain output, configured as in Table 1.

On all devices with open-drain outputs an external pullup resistor is required. The open-drain pullup resistor can connect to an external voltage up to +6V, regardless of the voltage at BATT.

Low-Power, 1%-Accurate Battery Monitor in µDFN and SC70 Packages

6 _______________________________________________________________________________________

Table 1. MAX6781 Outputs

DEVICE LBO1 LBO2

MAX6781 Push-Pull Open-Drain

Figure 2. Dual-Channel Fixed-Hysteresis Block Diagram

LBI

LBO

BATT

GND

REF

BATT

MAX6775 MAX6776

HYSTERESIS

CONTROL

Figure 1. Single-Channel Fixed-Hysteresis Block Diagram

LBL

LBO

LBH

BATT

GND

HYST

REF

BATT

MAX6777 MAX6778

Figure 3. Single-Channel Adjustable-Hysteresis Block Diagram

BATT

LBI1

HYSTERESIS

CONTROL

LBI2

GND

BATT

MAX6779 MAX6780 MAX6781

REF

LBO1

LBO2

MAX6775–MAX6781

Low-Power, 1%-Accurate Battery

Monitor in µDFN and SC70 Packages

_______________________________________________________________________________________ 7

The MAX6779, MAX6780, and MAX6781 monitor two battery levels or two independent voltages. A common application for this type of dual-battery monitor is to use one output as an early warning signal and the other as a dead-battery indicator.

Hysteresis

Input hysteresis defines two thresholds, separated by a small voltage (the hysteresis voltage), configured so the output asserts when the input falls below the falling threshold, and deasserts only when the input rises above the rising threshold. Figure 4 shows this graphically. Hysteresis removes, or greatly reduces, the possibility of the output changing state in response to noise or battery terminal voltage recovery after load removal.

Fixed Hysteresis

The MAX6775/MAX6776/MAX6779/MAX6780/MAX6781 have factory-set hysteresis for ease of use, and reduce component count. For these devices, the absolute hysteresis voltage is a percentage of the internally generated reference. The amount depends on the device option. “A” devices have 0.5% hysteresis, “B” devices have 5% hysteresis, and “C” devices have 10% hysteresis. Table 2 presents the threshold voltages for devices with internally fixed hysteresis.

Adjustable Hysteresis

The MAX6777/MAX6778 offer external hysteresis control through the resistive divider that monitors battery voltage. Figure 3 shows the connections for external hysteresis. See the Calculating an External Hysteresis Resistive Divider section for more information.

Applications Information

Resistor-Value Selection

Choosing the proper external resistors is a balance between accuracy and power use. The input to the voltage monitor, while high impedance, draws a small current, and that current travels through the resistive divider, introducing error. If extremely high resistor values are used, this current introduces significant error. With extremely low resistor values, the error becomes negligible, but the resistive divider draws more power from the battery than necessary and shortens battery life. Figure 1 calculates the optimum value for RHusing:

where eAis the maximum acceptable absolute resistive divider error (use 0.01 for 1%), V

BATT

is the battery volt-

age at which LBO should activate, and ILis the worstcase LBI leakage current. For example, with 0.5% accuracy, a 2.8V battery minimum, and 5nA leakage, RH= 2.80MΩ.

Calculate RLusing:

where V

LBIF

is the falling threshold voltage from Table 2.

Continuing the above example, select V

LBIF

= 1.0998V

(10% hysteresis device) and RL= 1.81MΩ.

VxR

LBIF H

LBIF BATT

= −

−

exV

A BATT

BATT

LBO

LBIR

LBIF

HYST

MAX6775 MAX6776

Figure 4. Hysteresis

Table 2. Typical Falling and Rising Thresholds for MAX6775/MAX6776/MAX6779/MAX6780/MAX6781

DEVICE OPTION

PERCENT

FALLING THRESHOLD

LBIF

) (V)

RISING THRESHOLD

LBIR

) (V)

HYSTERESIS VOLTAGE

HYST

) (mV)

A 0.5 1.2159 1.222 6.11

B5 1.1609 1.222 61.1

C10 1.0998 1.222 122

HYSTERESIS (%)

MAX6775–MAX6781

Low-Power, 1%-Accurate Battery Monitor in µDFN and SC70 Packages

8 _______________________________________________________________________________________

Selector Guide

PART LBO OUTPUT OUTPUT TYPE HYSTERESIS PIN-PACKAGE

MAX6775XK_+T Single Push-Pull Fixed 5 SC70-5

MAX6775LT_+T Single Push-Pull Fixed 6 µDFN-6

MAX6776XK_+T Single Open-Drain Fixed 5 SC70-5

MAX6776LT_+T Single Open-Drain Fixed 6 µDFN-6

MAX6777XK+T Single Push-Pull Adjustable 5 SC70-5

MAX6777LT+T Single Push-Pull Adjustable 6 µDFN-6

MAX6778XK+T Single Open-Drain Adjustable 5 SC70-5

MAX6778LT+T Single Open-Drain Adjustable 6 µDFN-6

MAX6779LT_+T Dual Push-Pull Fixed 6 µDFN-6

MAX6780LT_+T Dual Open-Drain Fixed 6 µDFN-6

MAX6781LT_+T Dual Mixed Fixed 6 µDFN-6

Calculating an External

Hysteresis Resistive Divider

Setting the hysteresis externally requires calculating three resistor values, as indicated in Figure 3. First calculate RHusing:

and RL0using:

(as in the above example). Where RL0equals RL+ R

HYST

, determine the total resistor-divider current,

TOTAL

, at the trip voltage using:

Then, determine R

HYST

using:

where V

HYST

is the required hysteresis voltage.

Finally, determine RLusing:

RL= RL0- R

HYST

Monitoring a Battery Voltage Higher

Than the Allowable V

BATT

For monitoring higher voltages, supply power to BATT that is within the specified supply range, and power the input resistive divider from the high voltage to be monitored. Do not exceed the Absolute Maximum Ratings.

Adding External Capacitance to

Reduce Noise and Transients

If monitoring voltages in a noisy environment, add a bypass capacitor of 0.1µF from BATT to GND as close as possible to the device. For systems with large transients, additional capacitance may be required. A small capacitor (<1nF) from LBI_ to GND may provide additional noise immunity.

HYST

TOTAL

BATT

VxR

LBIR H

LBIR BATT

−

exV

A BATT

MAX6775–MAX6781

Low-Power, 1%-Accurate Battery

Monitor in µDFN and SC70 Packages

_______________________________________________________________________________________ 9

Top Marks

PART TOP MARK

MAX6775XKA+T ASA

MAX6775XKB+T ASB

MAX6775XKC+T ASC

MAX6775LTA+T BU

MAX6775LTB+T BW

MAX6775LTC+T BX

MAX6776XKA+T ASJ

MAX6776XKB+T ASK

MAX6776XKC+T ASL

MAX6776LTA+T BY

MAX6776LTB+T BZ

MAX6776LTC+T CA

Ordering Information (continued)

PART TEMP RANGE PIN-PACKAGE

MAX6778XK+T* -40°C to +85°C 5 SC70-5

MAX6778LT+T* -40°C to +85°C 6 µDFN-6

MAX6779LT_+T* -40°C to +85°C 6 µDFN-6

MAX6780LT_+T* -40°C to +85°C 6 µDFN-6

MAX6781LT_+T* -40°C to +85°C 6 µDFN-6

+Denotes lead-free package.

Chip Information

PROCESS: BICMOS

TRANSISTOR COUNT: 496

PART TOP MARK

MAX6777XK+T ASD

MAX6777LT+T CB

MAX6778XK+T ASI

MAX6778LT+T CC

MAX6779LTA+T BL

MAX6779LTB+T BM

MAX6779LTC+T BN

MAX6780LTA+T BO

MAX6780LTB+T BP

MAX6780LTC+T BQ

MAX6781LTA+T BR

MAX6781LTB+T BS

MAX6781LTC+T BT

MAX6775–MAX6781

Low-Power, 1%-Accurate Battery Monitor in µDFN and SC70 Packages

10 ______________________________________________________________________________________

GND

LBOLBI

15BATTGND2

MAX6775 MAX6776

SC70-5

TOP VIEW

123

456

BATT LBON.C.

GND2 LBIGND

MAX6775 MAX6776

µDFN-6

123

456

BATT LBON.C.

LBH LBLGND

MAX6777 MAX6778

µDFN-6

123

456

BATT LBO1LBO2

LBI2 LBI1GND

MAX6779 MAX6780 MAX6781

µDFN-6

GND

LBOLBL

15BATTLBH

MAX6777 MAX6778

SC70-5

Pin Configurations

MAX6775–MAX6781

Low-Power, 1%-Accurate Battery

Monitor in µDFN and SC70 Packages

______________________________________________________________________________________ 11

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

6L UDFN.EPS

TOP VIEW

SIDE VIEW

PIN 1

INDEX AREA

A 0.64

COMMON DIMENSIONS

PIN 1

0.075x45°

BOTTOM VIEW

MIN.

SECTION A-A

A A

NOM.

0.72 0.80

MAX.

0.20--A1 --

1.501.45D 1.55

1.000.95E 1.05

0.350.30L 0.40

----L1 0.08

----L2 0.05

0.200.17b 0.23

0.50 BSC.e

AAA

TOPMARK

-DRAWING NOT TO SCALE-

DOCUMENT CONTROL NO.APPROVAL

TITLE:

REV.

PACKAGE OUTLINE, 6L uDFN, 1.5x1.0x0.8mm

21-0147

MAX6775–MAX6781

Low-Power, 1%-Accurate Battery Monitor in µDFN and SC70 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.

12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

Heaney

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

SC70, 5L.EPS

PACKAGE OUTLINE, 5L SC70

21-0076

Rainbow Electronics MAX6781 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual