NE57605CD

INTEGRATED CIRCUITS NE57605 Lithium-ion battery protector for 3 or 4 cell battery packs Product data 2001 Oct 03 Philips Semiconductors Philips Semiconductors Product data Lithium-ion battery protector for 3 or 4 cell battery packs NE57605 GENERAL DESCRIPTION The NE57605 is a 3-4-cell Li-ion protection IC. Its over- and under-voltage accuracy is trimmed to within ±25 mV (5%), and is available to match the requirements of all lithium-ion cells manufactured in the market today. FEATURES • Trimmed overvoltage trip point to within ±25 mV • Programmable overvoltage trip time delay • Trimmed undervoltage trip point to within ±25 mV • Very low undervoltage sleep quiescent current 2 mA. • Discharge overcurrent cutoff. • Low operating current (10 mA). • Very small package (TSOP-20A). SIMPLIFIED SYSTEM DIAGRAM VC4 OV REF APPLICATIONS • Laptop Computers • Other battery-powered devices VCC VCC UV REF VC3 OV REF OV DEADTIME CONTROL VCC CF UV REF CDLY(OV) VC2 OV REF SEL UV REF VC1 OV REF VCC SEL UV REF GND CHARGER DETECTOR SEL CS OC REF OVERCURRENT DEADTIME CONTROL CON CDLY(UV) CDLY(OC) OD DEADTIME CONTROL DF SL01582 Figure 1. Simplified system diagram. 2001 Oct 03 2 853-2295 27198 Philips Semiconductors Product data Lithium-ion battery protector for 3 or 4 cell battery packs NE57605 ORDERING INFORMATION PACKAGE TYPE NUMBER NUMBER NE57605CD NAME TSOP-20A DESCRIPTION plastic thin shrink small outline package; 20 leads; body width 4.4 mm TEMPERATURE RANGE –20 to +70 °C Part number marking Each device is marked with a four letter code. The first three letters in the top line of markings designate the product. The fourth letter, represented by “x”, is a date code. The remaining markings are manufacturing codes. Part Number NE57605CD Marking ALZx PIN CONFIGURATION CF NC CS NC DF NC CDLY(UV) CDLY(OC) CDLY(OV) 1 2 3 4 5 6 7 8 9 20 VCC 19 NC 18 VC4 17 VC3 16 VC2 15 VC1 14 NC 13 CON 12 NC 11 SEL GND 10 SL01583 Figure 2. Pin configuration. PIN DESCRIPTION PIN 1 SYMBOL CF I/O Output DESCRIPTION Overcharge detection output pin. NPNTr open collector output. Normal: high impedance. Overcharge: LOW. Not Connected. Overcurrent detection pin. Monitors load current equivalently by the voltage drop between discharge control FET source and drain, and makes DF pin HIGH when the voltage goes below overcurrent detection voltage, turning off discharge control FET. After overcurrent detection, current flows from this pin and when there is a light load, overcurrent mode is released. This function does not operate in overdischarge mode. Discharge control FET (P-ch) drive pin. Normal: LOW. Overdischarge: HIGH. Overdischarge detection dead time setting pin. Dead time can be set by connecting a capacitor between CDLY(UV) pin and ground. Overcurrent detection dead time setting pin. Dead time can be set by connecting a capacitor between CDLY(OC) pin and ground. Overcharge detection dead time setting pin. Dead time can be set by connecting a capacitor between CDLY(OV) pin and ground. Ground pin. 3/4 cell selection pin. SEL pin = GND: 3 cell (Connect VC1 to GND). SEL pin = VCC: 4 cell. Discharge FET ON/OFF pin. CON pin LOW; DF pin LOW (Normal mode). CON pin HIGH; DF pin HIGH (Discharging prohibited). V1 cell high side voltage input pin. V2 cell high side voltage and V3 cell low side voltage input pin. V3 cell high side voltage and V4 cell low side voltage input pin. V4 cell high side voltage input pin. Power supply input pin. 2, 4, 6, 12, 14, 19 3 NC CS – Input 5 7 8 9 10 11 DF CDLY(UV) CDLY(OC) CDLY(OV) GND SEL Output Input Input Input – Input 13 CON Input 15 16 17 18 20 VC1 VC2 VC3 VC4 VCC Input Input Input Input – 2001 Oct 03 3 Philips Semiconductors Product data Lithium-ion battery protector for 3 or 4 cell battery packs NE57605 MAXIMUM RATINGS SYMBOL VCC(max) VCF(max) VSEL(max) VCON(max) Topr Tstg PD Power supply voltage CF pin impressed voltage SEL pin impressed voltage CON pin impressed voltage Operating ambient temperature range Storage temperature Power dissipation PARAMETER MIN. –0.3 –0.3 –0.3 –0.3 –20 –40 – MAX. +24 +24 +24 +24 +70 +125 300 UNIT V V V V °C °C mW ELECTRICAL CHARACTERISTICS Tamb = 25 °C; VIN = VCE, unless otherwise specified. SYMBOL ICC1 ICC2 ICC3 ICC4 ICC5 I1V4 I2V4 I3V4 IV3 IV2 IV1 VCELLU ∆VU tOV VCELLS VCELLD ∆VDS tCDC VOC ∆VOC tCOL1 tCOL2 tCOL3 ISODCH ISIDCH VTHDCH VTHDCL ISIOV ILKOV PARAMETER Current consumption 1 (VCC pin) Current consumption 2 (VCC pin) Current consumption 3 (VCC pin) Current consumption 4 (VCC pin) Current consumption 5 (VCC pin) Consumption current (V4 pin) 1 Consumption current (V4 pin) 2 Consumption current (V4 pin) 3 V3 pin input current V2 pin input current V1 pin input current Overcharge detection voltage Overcharge hysteresis voltage Overcharge sensing dead time Overdischarge detection voltage Discharge resume voltage Overdischarge hysteresis voltage Overdischarge sensing dead time Overcurrent detection voltage Overcurrent hysteresis voltage Overcurrent sensing dead time 1 Overcurrent sensing dead time 2 Overcurrent sensing dead time 3 DF pin source current DF pin sink current DF pin output voltage HIGH DF pin output voltage LOW OV pin sink current OV pin leak current CON pin LOW voltage CON pin HIGH voltage CON pin current SEL pin LOW voltage SEL pin HIGH voltage SEL pin current COL = 0.001 µF COL = 0.001 µF; VCC – CS > 1.0 V COL = 0.001 µF Load release conditions 500 kΩ VCELL = 1.8 V; SW1: A VDF = VCC–0.8 V VCELL = 3.5 V; SW1: A VDF = 0.8 V VCC–VDF; ISO = 20 µA; SW1: B VDF–GND; ISI = –20 µA; SW1: B VOV = 0.4 V; Tamb = –20 °C to +70 °C VOV = 24 V DF = HIGH DF = LOW VCELL = 3.5 V; CON = 0.4 V for 3 cell for 4 cell VCELL = 3.5 V; SEL = 0.4 V 20 20 – – 100 – – VCC–0.4 – – VCC–0.4 – – – – – – – – – 1 – – 1 – – 0.8 0.8 – 0.1 0.4 – 2 0.4 – 2 µA µA V V µA µA V V µA V V µA CONDITIONS VCELL = 4.4 V; CON = 0 V VCELL = 3.5 V; CON = 0 V VCELL = 1.8 V; CON = 0 V VCELL = 3.5 V; CON = VCC VCELL = 1.8 V; CON = VCC VCELL = 4.4 V VCELL = 3.5 V VCELL = 1.8 V VCELL = 3.5 V VCELL = 3.5 V VCELL = 3.5 V VCELL: 4.2 V → 4.4 V; Tamb = 0 ∼ 50 °C VCELL: 4.2 V → 4.4 V → 3.9 V COV = 0.1 µF VCELL: 3.5 V → 1.8 V VCELL: 1.8 V → 3.5 V VCELLD – VCELLS CDC = 0.1 µF VCC – VCS; DF Min. – – – – – – – – –300 –300 –300 4.10 – 0.5 2.20 2.85 0.45 0.5 135 – 5 – 5 Typ. 55 27 2 12 1 10 8 2.5 0 0 0 4.35 200 1.0 2.30 3.00 0.70 1.0 150 20 10 1.5 10 Max. 110 50 4 20 2 20 15 5.0 +300 +300 +300 4.60 260 1.5 2.40 3.15 0.95 1.5 165 40 15 3.0 15 UNIT µA µA µA µA µA µA µA µA nA nA nA V mV s V V V s mV mV ms ms ms Overcurrent reset conditions 2001 Oct 03 4 Philips Semiconductors Product data Lithium-ion battery protector for 3 or 4 cell battery packs NE57605 TECHNICAL DISCUSSION Lithium cell safety Lithium-ion and lithium-polymer cells have a higher energy density than that of nickel-cadmium or nickel metal hydride cells and have a much lighter weight. This makes the lithium cells attractive for use in portable products. However, lithium cells require a protection circuit within the battery pack because certain operating conditions can be hazardous to the battery or the operator, if allowed to continue. Lithium cells have a porous carbon or graphite anode where lithium ions can lodge themselves in the pores. The lithium ions are separated, which avoids the hazards of metallic lithium. If the lithium cell is allowed to become overcharged, metallic lithium plates out onto the surface of the anode and volatile gas is generated within the cell. This creates a rapid-disassembly hazard (the battery ruptures). If the cell is allowed to over-discharge (Vcell less than approximately 2.3 V), then the copper metal from the cathode goes into the electrolyte solution. This shortens the cycle life of the cell, but presents no safety hazard. If the cell experiences excessive charge or discharge currents, as happens if the wrong charger is used, or if the terminals short circuit, the internal series resistance of the cell creates heating and generates the volatile gas which could rupture the battery. The protection circuit continuously monitors the cell voltage for an overcharged condition or an overdischarged condition. It also continuously monitors the output for an overcurrent condition. If any of these conditions are encountered, the protection circuit opens a series MOSFET switch to terminate the abnormal condition. The lithium cell protection circuit is placed within the battery pack very close to the cell. Charging control versus battery protection The battery pack industry does not recommend using the pack’s internal protection circuit to end the charging process. The external battery charger should have a charge termination circuit in it, such as that provided by the SA57611. This provides two levels of overcharge protection, with the primary protection of the external charge control circuit and the backup protection from the battery pack’s protection circuit. The charge termination circuit will be set to stop charging at a level around 50 mV less than the overvoltage threshold voltage of the battery pack’s own protection circuit. Lithium cell operating characteristics The internal resistance of lithium cells is in the 100 mΩ range, compared to the 5–20 mΩ of the nickel-based batteries. This makes the Lithium-ion and polymer cells better for lower battery current applications (less than 1 ampere) as found in cellular and wireless telephones, palmtop and laptop computers, etc. The average operating voltage of a lithium-ion or polymer cell is 3.6 V as compared to the 1.2 V of NiCd and NiMH cells. The typical discharge curve for Lithium cell is shown in Figure 3. OPEN-CIRCUIT CELL VOLTAGE (V) 4.0 VOV 3.0 VUV 2.0 50 NORMALIZED CELL CAPACITY (%) 100 SL01553 Figure 3. Lithium discharge curve. 2001 Oct 03 5 Philips Semiconductors Product data Lithium-ion battery protector for 3 or 4 cell battery packs NE57605 Charging Lithium cells CHARGE CURRENT (%C) The lithium cells must be charged with a dedicated charging IC such as the NE57610. These dedicated charging ICs perform a current-limited, constant-voltage charge, as shown in Figure 4. The charger IC begins charging with a current that is typically the rating of the cell (1C) or the milliampere rating of the cell. As the cell approaches its full-charge voltage rating (VOV), the current entering the cell decreases, and the charger IC provides a constant voltage. When the charge current falls below a preset amount, 5 mA for example, the charge is discontinued. If charging is begun below the overdischarged voltage rating of the cell, it is important to slowly raise the cell voltage up to this overdischarged voltage level. This is done by a reconditioning charge. A small amount of current is provided to the cell (50 mA for example), and the cell voltage is allowed a period of time to rise to the overdischarged voltage. If the cell voltage recovers, then a normal charging sequence can begin. If the cell does not reach the overdischarged voltage level, then the cell is too damaged to charge and the charge is discontinued. To take advantage of the larger energy density of lithium cells it is important to allow enough time to completely charge the cell. When the charger switches from constant current to constant voltage charge (Point B, Figure 4) the cell only contains about 80 percent of its full capacity. When the cell is 100 mV less than its full rated charge voltage the capacity contained within the cell is 95 percent. Hence, allowing the cell to slowly complete its charge takes advantage of the larger capacity of the lithium cells. 1.0 0.5 CONSTANT CURRENT CONSTANT VOLTAGE 1.0 TIME (HOURS) 2.0 Vov OPEN-CIRCUIT CELL VOLTAGE (V) 4.0 Point B 3.0 1.0 TIME (HOURS) 2.0 SL01554 Figure 4. Lithium Cell charging Curves 2001 Oct 03 6 Philips Semiconductors Product data Lithium-ion battery protector for 3 or 4 cell battery packs NE57605 APPLICATION INFORMATION The typical 4-cell lithium-ion or polymer protection circuit based upon the NE57605 is seen in Figure 5. With a minor redesign, the NE57605 3-cell system is shown in Figure 6. Pin 11 (SEL) is connected to ground. The NE57605 drives the series P-Channel MOSFETs to states determined by each of the cell’s voltage and the battery pack load current. During normal periods of operation, both the discharge and charge MOSFETs are in the ON state, thus allowing bi-directional current flow. If the battery pack is being charged, and any of the cell’s voltage exceeds the overvoltage threshold, then the charge MOSFET is turned OFF (the charge FET is the FET closest to the pack’s external terminal). The cell’s voltage must fall lower than the overvoltage hysteresis voltage (VOV(hyst)) before the charge MOSFET is again turned ON. If the battery pack is being discharged and the undervoltage threshold (VUV(th)) is exceeded by any of the cells, then the discharge MOSFET is turned OFF. It will not run back ON until a charger is applied to the pack’s external terminals and the cell’s voltage rises above the undervoltage hysteresis voltage (VUV(hyst)). When the battery pack is being discharged, the load current causes the voltage across the discharge MOSFET to increase past the overcurrent threshold voltage (VOC(th)), then the discharge MOSFET is turned OFF after a fixed 7–18 ms delay. If short-circuit is placed across the pack’s terminals, then the discharge MOSFET is turned OFF after a 100–300 µs time delay to avoid damaging the MOSFETs. 330 Ω VC4 Li-ION CELL 4 1 kΩ VC3 Li-ION CELL 3 1 kΩ 0.1 µF VC2 0.1 µF 0.1 µF 330 Ω 0.1 µF DISCHARGE FET CHARGE FET V+ 10 kΩ 47 kΩ VCC DF CS CF 10 kΩ NE57605 910 kΩ Li-ION CELL 2 CDLY(UV) SEL CDLY(OV) VC1 GND CON CDLY(OC) V– SYSTEM GROUND REFERENCE SL01585 Figure 6. 3-cell protection circuit DISCHARGE FET CHARGE FET V+ FET STATUS FOR NORMAL AND ABNORMAL CONDITIONS Operating Mode and Charging Condition Normal (charging or discharging) 10 kΩ 330 Ω 330 Ω 0.1 µF 1 kΩ VC3 Li-ION CELL 3 1 kΩ VC2 Li-ION CELL 2 1 kΩ VC1 Li-ION CELL 1 0.1 µF 0.1 µF 0.1 µF 0.1 µF 47 kΩ Li-ION CELL 4 VC4 SEL VCC DF CS CF 10 kΩ Charge FET (CF) ON OFF ON OFF ON OFF Discharge FET (DF) ON ON ON OFF ON OFF Overcharge (charging) Overcharge (discharging) Overdischarge (discharging) NE57605 910 kΩ Overdischarge (charging) Overcurrent (charging or discharging) CDLY(UV) CDLY(OV) Normal mode: Overdischarge detection voltage < battery voltage < overcharge detection voltage Discharge current < overcurrent detection level Overcharge mode: Battery voltage > overcharge detection voltage V– GND CON CDLY(OC) SYSTEM GROUND REFERENCE Overdischarge mode: Overdischarge detection voltage > battery voltage Overcurrent mode: Discharge current > overcurrent detection level voltage between VM and GND = discharge current × FET ON resistance (discharge or charge FET) SL01584 Figure 5. 4-cell protection circuit 2001 Oct 03 7 Philips Semiconductors Product data Lithium-ion battery protector for 3 or 4 cell battery packs NE57605 The R-C filters around the NE57605 One needs to place R-C filters on the positive input pins of the NE57605. These are primarily to shield the IC from electrostatic occurrences and spikes on the terminals of the battery pack. A secondary need is during the occurrence of a short-circuit across the battery pack terminals. Here, the Li-ion cell voltage could collapse and cause the IC to enter an unpowered state. The R-Cs then provide power during the first instance of the short circuit and allow the IC to turn OFF the discharge MOSFET. The IC can then enter an unpowered state. Lastly, the R-C filter on the node between the cells filters any noise voltage caused by noisy load current. The value of 330 Ω and 0.1 µF are good for the VCC and VC4 pins. Values of 1 kΩ and 0.1 µF are good for the VC1, VC2 and VC3 pins. though, is more defined by the total series resistance of the battery pack. The total resistance of the battery pack is given by Equation 1. Rbat(tot) = 2(RDS(on)) + 4Rcell (Equation 1) The total pack resistance is typically determined by the system requirements. The total pack resistance directly determines how much voltage droop will occur during pulses in load current. Another consideration is the forward-biased safe operating area of the MOSFET. During a short-circuit, the discharge current can easily reach 10–15 times the “C-rating” of the cells. The MOSFET must survive this current prior to the discharge MOSFET can be turned OFF. So having an FBSOA envelope that exceeds 20 amperes for 5 ms would be safe. The Charge MOSFET circuit The NE57605 uses an isolated charge MOSFET drive arrangement. This is to help keep ESD charges from entering the IC. The charge MOSFET is normally ON until turned off by the IC. The CF pin uses a current source to drive an external NPN transistor to turn OFF the charge FET. If a charge has poor “compliance” or the no load voltage of the charge can rise significantly above the rating of the battery pack. This condition causes the source of the charge FET to go very negative compared to the cell GND voltage after the charge FET opens. This design allows the charge FET gate drive to “float” down to this very negative voltage without upsetting the operation of the IC. Selecting the optimum MOSFETs For a 3- or 4-cell battery pack, a standard MOSFET should be used. These MOSFETs have turn-on thresholds of 2.5 V and are considered full-on at 10 V VGS. The total 4-cell pack voltage will be a maximum of 17.2 V, which is within safe operating range of the gate voltage which is typically around 20 volts. The MOSFETs should have a voltage rating greater than 30 V and should have a high avalanche rating to survive any spikes generated across the battery pack terminals. The current rating of the MOSFETs should be greater than four times the maximum “C-rating” of the cells. The current rating, PACKING METHOD GUARD BAND TAPE REEL ASSEMBLY TAPE DETAIL COVER TAPE CARRIER TAPE BARCODE LABEL BOX SL01305 Figure 7. Tape and reel packing method. 2001 Oct 03 8 Philips Semiconductors Product data Lithium-ion battery protector for 3 or 4 cell battery packs NE57605 TSOP-20A: plastic thin shrink small outline package; 20 leads; body width 4.4 mm 1.2 1.0 0.23 0.21 0.25 0.10 6.8 6.2 4.6 4.2 6.7 6.1 0.7 0.3 0.625 max. 10° 0° TSOP-20A 2001 Oct 03 9 Philips Semiconductors Product data Lithium-ion battery protector for 3 or 4 cell battery packs NE57605 Data sheet status Data sheet status [1] Objective data Preliminary data Product status [2] Development Qualification Definitions This data sheet contains data from the objective specification for product development. Philips Semiconductors reserves the right to change the specification in any manner without notice. This data sheet contains data from the preliminary specification. Supplementary data will be published at a later date. Philips Semiconductors reserves the right to change the specification without notice, in order to improve the design and supply the best possible product. This data sheet contains data from the product specification. Philips Semiconductors reserves the right to make changes at any time in order to improve the design, manufacturing and supply. Changes will be communicated according to the Customer Product/Process Change Notification (CPCN) procedure SNW-SQ-650A. Product data Production [1] Please consult the most recently issued data sheet before initiating or completing a design. [2] The product status of the device(s) described in this data sheet may have changed since this data sheet was published. The latest information is available on the Internet at URL http://www.semiconductors.philips.com. Definitions Short-form specification — The data in a short-form specification is extracted from a full data sheet with the same type number and title. For detailed information see the relevant data sheet or data handbook. Limiting values definition — Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 60134). Stress above one or more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended periods may affect device reliability. Application information — Applications that are described herein for any of these products are for illustrative purposes only. Philips Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or modification. Disclaimers Life support — These products are not designed for use in life support appliances, devices or systems where malfunction of these products can reasonably be expected to result in personal injury. Philips Semiconductors customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Philips Semiconductors for any damages resulting from such application. Right to make changes — Philips Semiconductors reserves the right to make changes, without notice, in the products, including circuits, standard cells, and/or software, described or contained herein in order to improve design and/or performance. Philips Semiconductors assumes no responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these products, and makes no representations or warranties that these products are free from patent, copyright, or mask work right infringement, unless otherwise specified. Contact information For additional information please visit http://www.semiconductors.philips.com. Fax: +31 40 27 24825 © Koninklijke Philips Electronics N.V. 2001 All rights reserved. Printed in U.S.A. Date of release: 10-01 For sales offices addresses send e-mail to: sales.addresses@www.semiconductors.philips.com. Document order number: 9397 750 08991 Philips Semiconductors 2001 Oct 03 10