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19-3774; Rev 2; 1/06
Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages
General Description
The MAX6775-MAX6781 low-power, 1%-accurate battery monitors are available in the ultra-small DFN 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 DFN packages, and is fully specified over the -40C to +85C extended temperature range.
Features
1.0%-Accurate Threshold Specified Over Temperature Single/Dual, Low-Battery Output Options Low 3A 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 VBATT = 1V Immune to Short Battery Transients Fully Specified from -40C to +85C Small 5-Pin SC70 or Ultra-Small 6-Pin DFN (1mm x 1.5mm) Package
MAX6775-MAX6781
Ordering Information
PART MAX6775XK_+T MAX6775LT_+T* MAX6776XK_+T MAX6776LT_+T MAX6777XK+T MAX6777LT+T TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 5 SC70-5 6 DFN-6 5 SC70-5 6 DFN-6 5 SC70-5 6 DFN-6
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.
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
3.6V
Typical Operating Circuit
BATT MAX6775 LBI LBO
IN DC-DC CONVERTER SHDN OUT
Pin Configurations appear at end of data sheet. ________________________________________________________________ Maxim Integrated Products 1
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.
Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages MAX6775-MAX6781
ABSOLUTE MAXIMUM RATINGS
BATT to GND............................................................-0.3V to +6V LBI, LBL, LBH, LBI1, LBI2 to GND ...............-0.3V to minimum of ((VBATT + 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 ((VBATT + 0.3V) and +6V) Input Current (all pins) ........................................................20mA Output Current (all pins) .....................................................20mA Continuous Power Dissipation (TA = +70C) 5-Pin SC70 (derate 3.1mW/C above +70C) ..............247mW 6-Pin DFN (derate 2.1mWC above +70C) ..............168mW Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VBATT = 1.6V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1)
PARAMETER Operating Voltage Range (Note 2) Supply Current SYMBOL VBATT IQ CONDITIONS TA = 0C to +70C TA = -40C to +85C VBATT = 3.7V, no load VBATT = 1.8V, no load 0.5% hysteresis version LBI, LBI_ Falling Threshold (Note 3) LBI Rising Threshold LBI Input Leakage Current LBL, LBH Threshold LBL, LBH Input Leakage Current VLBIF VLBIR 0.2V VLBI VBATT - 0.2V VBATT = 1.8V to 5.5V VBATT - 0.2V VLBL/LBH 0.2V 5% hysteresis version 10% hysteresis version 1.2037 1.1493 1.0888 1.2098 -5 1.2098 -5 1.222 MIN 1.0 1.2 4 3.2 1.2159 1.1609 1.0998 1.222 TYP MAX 5.5 5.5 7 6 1.2280 1.1725 1.1108 1.2342 +5 1.2342 +5 V nA V nA V UNITS V A
FIXED HYSTERESIS (MAX6775/MAX6776/MAX6779/MAX6780/MAX6781)
ADJUSTABLE HYSTERESIS (MAX6777/MAX6778)
2
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Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages
ELECTRICAL CHARACTERISTICS (continued)
(VBATT = 1.6V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1)
PARAMETER Propagation Delay Startup Time Output Low (Push-Pull or Open-Drain) VOL SYMBOL tPD CONDITIONS VLBI_ + 100mV to VLBI_ - 100mV VBATT rising above 1.6V VBATT 1.2V, ISINK = 100A VBATT 2.7V, ISINK = 1.2mA VBATT 4.5V, ISINK = 3.2mA VBATT 1.6V, ISOURCE = 100A Output High (Push-Pull ) VOH VBATT 2.7V, ISOURCE = 500A VBATT 4.5V, ISOURCE = 800A Output Leakage Current (Open-Drain) Output not asserted, VLBO_ = 5.5V 0.8 x VBATT 0.8 x VBATT 0.8 x VBATT -100 +100 nA V MIN TYP 9 3 0.3 0.3 0.3 V MAX UNITS s ms LOW-BATTERY OUTPUTS (LBO, LBO1, LBO2)
MAX6775-MAX6781
Note 1: Devices are tested at TA = +25C and guaranteed by design for TA = TMIN to TMAX, 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.
Typical Operating Characteristics
(TA = +25C, unless otherwise noted.)
MAXIMUM TRANSIENT DURATION vs. THRESHOLD OVERDRIVE
MAX6775 toc02
SUPPLY CURRENT vs. TEMPERATURE
MAX6775 toc01
PROPAGATION DELAY vs. TEMPERATURE
12 VBATT = 1.6V PROPAGATION DELAY (s) 11 70 MAXIMUM TRANSIENT DURATION (s) 60 50 40 30 20 10 0 85 1
OUTPUT ASSERTED ABOVE THIS LINE
5.5 SUPPLY CURRENT (A) 5.0 4.5 4.0 3.5 3.0 2.5 -40 -15 10 35 60 VBATT = 2.4V VBATT = 1.6V VBATT = 5V VBATT = 3.6V VBATT = 3V
10 VBATT = 5V 9
8 100mV OVERDRIVE 85 7 -40 -15 10 35 60
10
100
1000
TEMPERATURE (C)
TEMPERATURE (C)
THRESHOLD OVERDRIVE VTH - VCC (mV)
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MAX6775 toc03
6.0
3
Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages MAX6775-MAX6781
Typical Operating Characteristics (continued)
(TA = +25C, unless otherwise noted.)
NORMALIZED THRESHOLD VOLTAGES vs. TEMPERATURE, MAX67__A
MAX6775 toc04
NORMALIZED THRESHOLD VOLTAGES vs. TEMPERATURE, MAX67__B
MAX6775 toc05
NORMALIZED THRESHOLD VOLTAGES vs. TEMPERATURE, MAX67__C
NORMALIZED AT TA = +25C
MAX6775 toc06
1 0 THRESHOLD VOLTAGE (mV)
NORMALIZED AT TA = +25C
1
NORMALIZED AT TA = +25C
1
THRESHOLD VOLTAGE (mV)
RISING -1 FALLING -2 -3 -4 -5 -40 -15 10 35 60 85 TEMPERATURE (C)
RISING FALLING
THRESHOLD VOLTAGE (mV)
0
0 FALLING RISING -1
-1
-2
-3
-2
-4 -40 -15 10 35 60 85 TEMPERATURE (C)
-3 -40 -15 10 35 60 85 TEMPERATURE (C)
LBO OUTPUT VOLTAGE vs. SINK CURRENT
MAX6775 toc07
LBO OUTPUT VOLTAGE vs. SOURCE CURRENT
5.0 4.5 OUTPUT VOLTAGE (V) 4.0 3.5 3.0 2.5 2.0 1.5 VBATT = 1.8V VBATT = 3.3V
MAX6775 toc08
0.5 VBATT = 1.8V 0.4 OUTPUT VOLTAGE (V) VBATT = 3.3V
5.5 VBATT = 5.0V
0.3
0.2
VBATT = 5.0V
0.1
0 0 3 6 9 12 15 SINK CURRENT (mA)
1.0 0 1 2 3 4 5 SOURCE CURRENT (mA)
4
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Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages
Pin Description
MAX6775/ MAX6776 DFN 1 2 3 SC70 1 2 3 MAX6777/ MAX6778 DFN -- 2 -- SC70 -- 2 -- MAX6779/ MAX6780/ MAX6781 DFN -- 2 -- GND2 GND LBI Reserved. Must be connected to GND. Do not use as the only GND connection. Ground Low-Battery Input. Connect to the resistive divider to set the trip level. Low-Battery Output, Active-Low. When VLBI/VLBL falls below the falling threshold, LBO asserts. LBO deasserts when VLBI/VLBH exceeds the rising threshold voltage. No Connection. Not internally connected. Battery Input. Power supply to the device. Rising-Trip-Level Input. Connect to a resistive divider to set the rising trip level. Falling-Trip-Level Input. Connect to a resistive divider to set the falling trip level. Low-Battery Input 2. Connect to a resistive divider to set the trip level. Low-Battery Input 1. Connect to a resistive divider to set the trip level. Low-Battery Output 1, Active-Low. When VLBI1 falls below the falling threshold voltage, LBO1 asserts. LBO1 deasserts when VLBI1 exceeds the rising threshold voltage. LBO1 is push-pull on the MAX6779/MAX6781 and open-drain for the MAX6780. Low-Battery Output 2, Active-Low. When VLBI2 falls below the falling threshold voltage, LBO2 asserts. LBO2 deasserts when VLBI2 exceeds the rising threshold voltage. LBO2 is open-drain for the MAX6780/MAX6781 and push-pull for the MAX6779.
MAX6775-MAX6781
NAME
FUNCTION
4 5 6 -- -- -- --
4 -- 5 -- -- -- --
4 5 6 1 3 -- --
4 -- 5 1 3 -- --
-- -- 6 -- -- 1 3
LBO N.C. BATT LBH LBL LBI2 LBI1
--
--
--
--
4
LBO1
--
--
--
--
5
LBO2
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5
Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages 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.
VBATT BATT
LBI1
MAX6779 MAX6780 MAX6781 1 HYSTERESIS CONTROL LBO1
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.
LBI2
0
VREF
0 LBO2 1
GND
Table 1. MAX6781 Outputs
DEVICE MAX6781 LBO1 Push-Pull LBO2 Open-Drain
Figure 2. Dual-Channel Fixed-Hysteresis Block Diagram
VBATT BATT RH MAX6775 MAX6776 LBI RL HYSTERESIS CONTROL 1 LBO
VBATT BATT RH MAX6777 MAX6778 LBL RHYST LBH 0 VREF GND RL VREF GND 0 LBO 1
Figure 1. Single-Channel Fixed-Hysteresis Block Diagram
Figure 3. Single-Channel Adjustable-Hysteresis Block Diagram
6
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Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages
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. 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.
MAX6775-MAX6781
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.
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 RH using: RH = eA x VBATT IL
VBATT VLBIR
MAX6775 MAX6776
where eA is the maximum acceptable absolute resistive divider error (use 0.01 for 1%), VBATT is the battery voltage at which LBO should activate, and IL is the worstcase LBI leakage current. For example, with 0.5% accuracy, a 2.8V battery minimum, and 5nA leakage, RH = 2.80M. Calculate RL using: RL =
-
VHYST VLBIF
VLBIF x RH VLBIF - VBATT
tPD LBO
tPD
where VLBIF is the falling threshold voltage from Table 2. Continuing the above example, select VLBIF = 1.0998V (10% hysteresis device) and RL = 1.81M.
Figure 4. Hysteresis
Table 2. Typical Falling and Rising Thresholds for MAX6775/MAX6776/MAX6779/MAX6780/MAX6781
DEVICE OPTION A B C PERCENT HYSTERESIS (%) 0.5 5 10 FALLING THRESHOLD (VLBIF) (V) 1.2159 1.1609 1.0998 RISING THRESHOLD (VLBIR) (V) 1.222 1.222 1.222 HYSTERESIS VOLTAGE (VHYST) (mV) 6.11 61.1 122
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7
Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages MAX6775-MAX6781
Calculating an External Hysteresis Resistive Divider
Setting the hysteresis externally requires calculating three resistor values, as indicated in Figure 3. First calculate RH using: RH = and RL0 using: RL0 =
-
where VHYST is the required hysteresis voltage. Finally, determine RL using: RL = RL0 - RHYST
eA x VBATT IL
Monitoring a Battery Voltage Higher Than the Allowable VBATT
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.
VLBIR x RH VLBIR - VBATT
Adding External Capacitance to Reduce Noise and Transients
If monitoring voltages in a noisy environment, add a bypass capacitor of 0.1F 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.
(as in the above example). Where RL0 equals RL + R HYST , determine the total resistor-divider current, ITOTAL, at the trip voltage using: I TOTAL = VBATT RH + RL0
Then, determine RHYST using: RHYST = VHYST I TOTAL
Selector Guide
PART MAX6775XK_+T MAX6775LT_+T MAX6776XK_+T MAX6776LT_+T MAX6777XK+T MAX6777LT+T MAX6778XK+T MAX6778LT+T MAX6779LT_+T MAX6780LT_+T MAX6781LT_+T LBO OUTPUT Single Single Single Single Single Single Single Single Dual Dual Dual OUTPUT TYPE Push-Pull Push-Pull Open-Drain Open-Drain Push-Pull Push-Pull Open-Drain Open-Drain Push-Pull Open-Drain Mixed HYSTERESIS Fixed Fixed Fixed Fixed Adjustable Adjustable Adjustable Adjustable Fixed Fixed Fixed PIN-PACKAGE 5 SC70-5 6 DFN-6 5 SC70-5 6 DFN-6 5 SC70-5 6 DFN-6 5 SC70-5 6 DFN-6 6 DFN-6 6 DFN-6 6 DFN-6
8
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Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages
Top Marks
PART MAX6775XKA+T MAX6775XKB+T MAX6775XKC+T MAX6775LTA+T MAX6775LTB+T MAX6775LTC+T MAX6776XKA+T MAX6776XKB+T MAX6776XKC+T MAX6776LTA+T MAX6776LTB+T MAX6776LTC+T TOP MARK ASA ASB ASC BU BW BX ASJ ASK ASL BY BZ CA PART MAX6777XK+T MAX6777LT+T MAX6778XK+T MAX6778LT+T MAX6779LTA+T MAX6779LTB+T MAX6779LTC+T MAX6780LTA+T MAX6780LTB+T MAX6780LTC+T MAX6781LTA+T MAX6781LTB+T MAX6781LTC+T TOP MARK ASD CB ASI CC BL BM BN BO BP BQ BR BS BT
MAX6775-MAX6781
Ordering Information (continued)
PART MAX6778XK+T MAX6778LT+T MAX6779LT_+T MAX6780LT_+T MAX6781LT_+T TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 5 SC70-5 6 DFN-6 6 DFN-6 6 DFN-6 6 DFN-6
Chip Information
PROCESS: BICMOS TRANSISTOR COUNT: 496
+Denotes lead-free package. 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.
_______________________________________________________________________________________
9
Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages MAX6775-MAX6781
Pin Configurations
TOP VIEW
BATT N.C. 5 LBO 4
+
GND2 1 5 BATT 6
GND 2
MAX6775 MAX6776
4 LBO 1
MAX6775 MAX6776
2 GND 3 LBI
LBI 3
SC70-5
GND2
DFN-6
BATT N.C. 5 LBO 4 BATT 6 LBO2 5 LBO1 4
+
LBH 1 5 BATT 6
GND 2
MAX6777 MAX6778
4 LBO 1
MAX6777 MAX6778
2 GND 3 LBL 1 LBI2
MAX6779 MAX6780 MAX6781
2 GND 3 LBI1
LBL 3
SC70-5
LBH
DFN-6
DFN-6
10
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Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages
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
PIN 1 0.075x45
MAX6775-MAX6781
3
A
4 TOPMARK 2
e
5
b
6
PIN 1 INDEX AREA
AAA
1
E
L
L2
3
2 A A
1
D TOP VIEW
A1 SIDE VIEW
L1
BOTTOM VIEW
b
A A1 D E L L1 L2 b e
COMMON DIMENSIONS MIN. 0.64 -1.45 0.95 0.30 --0.17 NOM. 0.72 0.20 1.50 1.00 0.35 --0.20 0.50 BSC. MAX. 0.80 -1.55 1.05 0.40 0.08 0.05 0.23
SECTION A-A
TITLE:
PACKAGE OUTLINE, 6L uDFN, 1.5x1.0x0.8mm
APPROVAL DOCUMENT CONTROL NO. REV.
-DRAWING NOT TO SCALE-
21-0147
C
1
1
______________________________________________________________________________________
11
Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages MAX6775-MAX6781
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
C
1
1
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 (c) 2006 Maxim Integrated Products
Heaney
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.

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