AIC1781 Battery Charge Controller FEATURES DESCRIPTION Fast Charge Control of NiMH/NiCd Batteries, even with a Fluctuating Charging Current. Fast Charge Termination by: ∆T / ∆t , −∆V , 0 ∆V , Safety Timer, Maximum Temperature, Maximum Voltage. Linearly Adjustable ∆T / ∆t Detection Slope and Safety Timer. Adjustable Peak Voltage Timer for 0 ∆V . Battery Voltage Protection Range Selectable. Selectable Battery Temperature Protection Mode. Protection against Battery Voltage and Battery Temperature Faults. Selectable LED Display Mode for Battery Status. Five Pulsed Trickle Charge Modes. Discharge-before-Charge Function Available for Eliminating Memory Effect. Quick and Easy Testing for Production. 16-pin DIP or SO Packages. APPLICATIONS Battery Fast Chargers for: Mobile Phones. Notebook and Laptop Personal Computers. Portable Power Tools and Toys. Portable Communication Equipments. Portable Video & Stereo Equipments. 100 Charge Current = 600 mA Cell Capacity = 550 mA NiMH Battery 80 1.45 Cell Voltage 60 1.35 40 1.25 Temperature (°C) Cell Voltage (V) 1.55 Temperature 1.15 0 10 20 30 40 Charge Time (min.) 50 60 20 Fig. 1 Battery Charging Characteristics Resulting from an AIC1781-Controlled Charger with a Fluctuating Charging Current The AIC1781 fast charge controller IC is designed for intelligent charging of NiMH or NiCd batteries without the risk of overcharge. −∆V detection (-0.25%), 0 ∆V detection (peak voltage timer) and ∆T / ∆t detection are the primary methods employed by the AIC1781 to terminate fast charge. The fast charge can also be cut off by maximum battery voltage and maximum battery temperature detection along with the safety timer to prevent charging under fault conditions of the charging system or the battery itself. Both ∆T / ∆t and −∆V detection methods have been proved powerful in terminating fast charging for NiMH and NiCd batteries. The AIC1781 utilizes the combination of these two methods to achieve reliable decision of ending fast charge and prevent misaction caused by using −∆V detection alone under certain conditions. Fig. 1 shows an example of charging curve of a battery charged by a fluctuating current from a NiMH battery charger which uses the AIC1781 controller IC to achieve optimal charging. This technique, in cooperating with the 0 ∆V detection (peak voltage timer), is particularly suitable for NiMH batteries, whose voltage drop is hardly significant yet temperature rises rapidly. The ∆T / ∆t or −∆V detection circuitry may be disabled independently for different applications, such as system-integrated chargers, chargers with varying charge current, or battery packs lack of temperature sensing thermistor. The safety timer period, mode of battery temperature protection, battery voltage protection range, pulsed trickle charge duty, and LED display mode are all adjustable or selectable. Dischargebefore-charge function is included to get rid of memory effect of NiCd batteries without the risk of overdischarging. Test mode is provided for charger manufactures to dramatically reduce production test time. Analog Integrations Corporation 4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC DS-1781-00 TEL: 886-3-5772500 FAX: 886-3-5772510 www.analog.com.tw 1 AIC1781 TYPICAL APPLICATION CIRCUIT D1 R2 1K D2 L1 IN4148 C2 C4 220µF 2 3 C1 4 DC BOOST IS 1N5819 120K 4.7µF + 5 FB 1000P U3 1 + C12 1uF VIN Q1 3 DIS 680 47nF RX1 C3 R7 BAT1 RY1 100K 2 GND LED3 GREEN RED 4 LED1 VTS GND 2N3904 100K + C6 0.1µF 100µF C11 C8 0.1µF 7 R14 R18 8 200K 50K R11 ADJ SEL1 SEL3 SEL2 TMR MODE 16 R16 15 680 14 R17 680 13 12 11 10 9 AIC1781 100K R13 7805 VOUT LED2 VCC BATTERY VIN C7 0.1µF DSW ICON VBT R15 6 220µF AIC1563 U2 PEAK 5 VCC GND C9 1 2 C10 100K SW PB YELLOW R6 0.3/1W 6 CF R8 IN4148 7 DE + D4 D3 8 0.1µF LED2 R12 R10 100K R9 240K C5 THERMISTOR 1 20/5W IN4148 + U1 R4 270 LED1 220µH 1µF R5 120/0.5W 390K SW1 R3 R1 470K 3 Q2 2N3904 + C13 10µF Battery Charge Circuit for Fluctuating Charging Current Application ORDERING INFORMATION AIC1781XX ORDER NUMBER PACKAGE TYPE N: PLASTIC DIP S: SMALL OUTLINE AIC1781CN (PLASTIC DIP) PIN CONFIGURATION PEAK 1 16 DSW 2 15 ICON VBT DIS 3 14 LED2 VTS 4 13 LED1 AIC1781CS VCC 5 12 GND (PLASTIC SO) ADJ 6 11 SEL1 SEL3 7 10 SEL2 TEMPERATURE RANGE C= 0°C~70°C TMR 8 9 MODE ABSOLUTE MAXIMUM RATINGS Supply Voltage ............................................…………........................................ 5.5V DC Voltage Applied on any pin ......................……………...................................... 5.5V Sink current of ICON pin, LED1 and LED2 pin .......................……….................. 20mA Operating Temperature Range .....................................…………….............. 0°C~ 70°C Storage Temperature Range .............................................…………...... -65°C~ 150°C 2 AIC1781 TEST CIRCUIT VCC VOLTAGE SOURCE - DSW VBT ICON DIS LED2 VTS LED1 R3 + YELLOW R1 560 - PEAK + VOLTAGE SOURCE VCC (5V) VCC V1 (0.95V) V2 (3V) 100K AIC1781 ORANGE 560 R4 GREEN 560 R5 RED 560 VCC GND ADJ SEL1 SEL3 SEL2 VCC TMR MODE VCC VCC VCC R2 ELECTRICAL CHARACTERISTICS (Ta=25°°C, V CC=5V, PARAMETER SYMBOL MIN. TYP. MAX. UNIT Supply Voltage VCC 4.5 5.0 5.5 V Supply Current ICC Voltage Protection Limit TEST CONDITIONS unless otherwise specified.) Battery Low During Initial Timer After Initial Timer (SEL3>3V) (SEL3<2V) Battery High (SEL3>3V) (SEL3<2V) VBT 1.1 mA 0.11 0.16 0.21 0.63 1.1 0.69 1.2 0.75 1.30 2.6 2.7 2.80 1.9 2.0 2.10 V 3 AIC1781 ELECTRICAL CHARACTERISTICS (Ta=25°°C, V CC=5V, PARAMETER TEST CONDITIONS SYMBOL Temperature High Temperature Sense Limit VTS Temperature Low Output impedance of DIS Pin MIN. TYP. MAX. 1.35 1.45 1.55 3.5 3.6 3.70 140 250 Ω 25 50 Ω MΩ ZDIS LED1, LED2, ICON Pins ON OFF Output Impedance unless otherwise specified.) Source Current Capability SEL3 pin DSW pin Input Impedance MODE, PEAK, SEL1, SEL2 pins V 1 ISEL3 IDSW VBT, VTS, ADJ pins 5.5 16 µA 300 KΩ 1 Recommended External Resistor of TMR pin RTMR MΩ 2 100 -∆V Detection Level w.r.t.* Peak Value TYPICAL UNIT 1000 KΩ -0.25 PERFORMANCE CHARACTERISTICS % (Ta=25°°C, R2=100KΩ Ω, VCC=5V, refer to Test Circuit) Safety Timer vs Supply Volatge Supply Current vs Supply Voltage 1.21 81.0 Safety Timer (min.) Supply Current (mA) 1.18 1.12 1.06 80.5 80.0 79.5 1.00 4.4 4.6 4.8 5.0 VCC (V) 5.2 5.4 79.0 4.4 4.6 4.8 5.0 5.2 5.4 VCC (V) 4 AIC1781 TYPICAL PERFORMANCE CHARACTERISTICS LED Flashing Frequency vs Supply Voltage (Continued) Supply Current vs Temperature 4.8 1.26 Supply Current (mA) Frequency (Hz) 4.6 4.4 4.2 4.0 3.8 1.14 1.02 0.9 4.4 4.6 4.8 5.0 5.2 0 5.4 20 VCC (V) 40 Temperature (°C) 60 80 LED Flashing Frequency vs Temperature Safety Timer vs Temperature 5.0 82.0 Frequency (Hz) Safety Timer (min.) 4.6 81.0 4.2 80.0 3.8 79.0 0 20 40 60 3.4 0 80 20 Temperature(°C) 40 60 80 Temperature(°C) VBT (high) Limit vs Temperature (SEL3<2V) VBT (high) Limit vs Temperature (SEL3>3V) 2.74 2.03 VBT (V) VBT (V) 2.70 2.01 2.66 1.99 2.62 1.98 0 20 40 Temperature (°C) 60 80 0 20 40 60 80 Temperature (°C) 5 AIC1781 TYPICAL PERFORMANCE CHARACTERISTICS Output Impedance vs Temperature (LED1,LED2,ICON pins) VBT (low) Limit vs Temperature (During Initial Timer) 29 Output Impedance(Ω) 0.163 0.162 VBT (V) (Continued) 0.161 0.160 0.159 27 25 0.158 23 0 20 40 60 80 0 20 Temperature (°C) 40 60 80 Temperature (°C) VTS (high) Limit vs Temperature VTS (low) Limit vs Temperature 1.48 3.62 1.46 VTS (V) VTS (V) 3.61 3.60 1.44 3.59 3.58 0 20 40 Temperature (°C) 60 1.42 80 0 VBT(LOW) Limits vs Temperature (SEL3>3V, After Initial Timer) 20 40 Temperature (°C) 60 80 VBT(LOW) Limits vs Temperature (SEL3<3V, After Initial Timer) 1.24 0.700 0.695 VBT (V) VBT(V) 1.22 0.690 1.20 0.685 0 20 40 Temperature (°C) 1.18 60 80 0 20 40 60 80 Temperature (°C) 6 AIC1781 BLOCK DIAGRAM PEAK MODE Peak Voltage Timer Control SEL3 MODE Selection GND VCC Bandgap Reference & Voltage Regulator Battery Voltage & Temperature Portection Setting SEL2 LED‘s Display & Trickle Pulse Duty Setting ADJ ∆T/∆t Detection Setting LED2 Oscillator LED1 Charge Control SEL1 TMR State Machine Display Control Unit ICON Charge Control Unit DIS Battery Temp. Protection 13-bit A/D VTS Battery Voltage Protection Discharge Control Unit DSW VBT PIN DESCRIPTIONS PIN 1: PEAK- Tri-level input, determining the acceptable voltage range of period of peak voltage timer. VTS pin is 0.29 VCC to 0.72 (See 0∆V cut-off section in VCC. The battery temperature application informations.) is regarded as too high if the PIN 2: VBT- Divided battery voltage input to voltage of VTS pin is lower than sense the battery voltage. 0.29 VCC, and is otherwise PIN 3: DIS- Push-pull PIN 4: VTS- to regarded as too low if the control an external transistor to voltage of VTS pin is higher discharge the battery. DIS is than 0.72 VCC. output, used active high when the AIC1781 PIN 5: VCC- Power supply input at 5V±10%. enters discharge mode. PIN 6: ADJ- For adjusting the slope of ∆T/∆t. The battery cell temperature is Acceptable voltage range for represented as a voltage input this pin is approximately 0.28V to the AIC1781 at this pin. The to 3.8V. If voltage higher than 7 AIC1781 VCC-0.3V, the function of ∆T/∆t PIN 9: MODE- Determine the mode of operation for the AIC1781. detection is disabled. PIN 10: SEL2 & PIN 7: SEL3- PIN 8: TMR- Determine the acceptable PIN 11: SEL1- Tri-level inputs, that jointly voltage range of VBT pin and control the LED display mode mode of temperature protection and the duty of trickle charge function. after the completion of fast Determine the period of safety charge. timer with an external resistor PIN 12: GND- Power ground. connected to GND. APPLICATION INFORMATIONS THE AIC1781 OPERATION Power-on and Battery Pre-qualifying is registered for the fast charge cycle. To trigger this function, DSW pin has to be biased to GND for over 0.18 second. After discharge When power is first applied to the AIC1781, all begins, LED1 and LED2 pins are both off, ICON pin internal digital circuit blocks of the AIC1781 are reset is on, and DIS pin goes high to activate an external by the internal power-on-reset circuitry and output circuit to discharge the battery until the voltage of LEDs (depending on the setting of SEL1 and SEL2 VBT pin falls below 0.9V (or 0.69V, depending on pins) flash 3 times to indicate the initiation of power- the input voltage of SEL3 pin) or DSW pin is biased on. The internal control unit then examines the to GND for over 0.18 second again. Fast charge will battery condition through the VBT and VTS pins. automatically start after discharge is finished. The The acceptable limits of VBT pin is determined by application the input voltage of SEL3 pin and the acceptable APPLICATION CIRCUIT. temperature sense voltage window for VTS pin is 0.29 VCC to 0.72 VCC. If the voltage of VBT pin fails to fall within the predetermined acceptable limits, the AIC1781 enters a charge-suspending mode, in which all the internal circuitry remains in reset state. If the voltage of VTS pin is outside the 0.29 VCC to 0.72 VCC window, action of AIC1781 is determined by the input voltage of SEL3 pin. circuit is included in TYPICAL Fast Charge After the battery passes fault checks and required discharging of the battery is completed, fast charging begins while initial timer and safety timer of the AIC1781 start counting. Functions of -∆V detection, peak voltage timer, ∆T/∆t detection, and maximum battery voltage are, however, disabled temporarily until the initial timer period in the initial Discharge-Before-Charge stage of a charge cycle elapses. The initial timer The AIC1781 provides the function of discharge- period is equal to 1/80 of safety timer. before-charge to precondition NiCd batteries which Since the low limit of acceptable VBT voltage is suffer from memory effect. This function can only be only about 0.16V during the initial timer period, activated after the pre-qualification of battery voltage even deeply discharged batteries can easily qualify and temperature, yet before the charge completion to be fast charged subsequently. 8 AIC1781 In the course of fast charge, the AIC1781 constantly Maximum Safety Timer Cutoff monitors the voltages at VBT and VTS pins. The fast The maximum fast charge period is determined by charge process is switched to trickle charge when the safety timer, which is set by a resistor any one of the following situations is encountered, connected from TMR pin to GND. Safety timer, -∆V which are explained below: sampling rate, and ∆T/∆t sampling rate will be Negative delta voltage (-∆V) longer if the resistor value is larger. When the value Peak voltage timer (0 ∆V ) of the resistor is 100KΩ, the safety timer period Delta temperature/ delta time (∆T/∆t) equals 80 minutes. This can be verified by biasing Maximum charge time MODE pin to VCC and the measured frequency on Maximum battery voltage DSW pin should be around 32.8 KHz. After the Maximum battery temperature safety timer period is finished, the fast charge action is terminated. -∆V Cutoff The AIC1781 makes a voltage sampling at VBT pin Maximum Voltage and Temperature Cutoff every 4 seconds when safety timer period is set The AIC1781 guards against the maximum limits equal to 80 minutes. If a negative delta voltage of for battery voltage and temperature during fast 0.25% compared to its peak value is detected at charging. If either of these limits is exceeded, fast VBT pin, the fast charge cycle is terminated. charge action is terminated. 0∆V Cutoff Trickle Charge If the battery voltage stays at its peak value or There are five different selectable duty cycles for decreases very slowly for the duration determined trickle charge after the fast charge to prevent the by the peak voltage timer, which is in turn loss of charge due to battery self-discharging. The determined by PEAK pin voltage, the fast charge duty cycle is controlled by the setting of SEL1 and action is terminated. SEL2 pins. ∆T/∆t Cutoff The functions and charging states control The ∆T/∆t detection of the AIC1781 is performed by sensing the decrease of VTS pin voltage in a mentioned above are illustrated in the function flow chart of AIC1781 (Fig. 2) specific timer interval dictated by the safety timer. The fast charging terminates when the decrease of VTS pin voltage in 56 seconds exceeds the DESIGN GUIDE predetermined value set by ADJ pin input. This time Selecting Peak Voltage Timer (0∆V) interval of 56 seconds is based on the assumption The voltage of PEAK pin along with safety timer that voltage of VTS pin is sampled once for every 8 determines the period of peak voltage timer. It can seconds, which is also determined by safety timer. be selected according to the following table: Functioning of -∆V detection and peak voltage timer PEAK PIN PEAK VOLTAGE TIMER VCC 1.5% of safety timer disabled if the voltage of ADJ pin is higher than VCC Floating 3.7% of safety timer - 0.3V. GND 6% of safety timer (0 ∆V ) can be disabled if the MODE pin is biased to GND. Functioning of ∆T/∆t detection can be 9 AIC1781 Battery Voltage Measurement BATTERY CELLS RA/RB RA(KΩ) RB (KΩ) The AIC1781 measures the battery voltage through VBT pin, which is connected to battery positive 2 1 240 240 terminal through a resistor-divider network, as 3 2 240 120 4 3 240 80 5 4 300 75 6 5 300 60 8 7 360 51 10 9 360 40 12 11 390 36 16 15 410 27 shown in Fig. 3. The input voltage of SEL3 pin determines the acceptable limit of divided battery voltage. VBAT RA R5 C6 0.1µF 100K + C5 4.7µF RB 2 VBT AIC1781 Battery Temperature Measurement The AIC1781 employs a negative temperature coefficient (NTC) Battery Voltage Divider For SEL3 > (VCC/2) + 0.4V, the suggested divider resistance of RA and RB for the corresponding number of battery cells are as below: to measure the nonlinear with respect to temperature. To reduce the effect of nonlinearity, a resistor-divider network in parallel with the thermistor is recommended. A typical application circuit is shown in Fig. 4. RA/RB 2~4 2 240 120 3~6 3.3 300 91 4~8 4.9 300 62 5~10 6.4 300 47 6~12 7.8 310 39 8~16 10.8 390 36 RB (KΩ) For SEL3 < (VCC/2) – 0.4V, the suggested divider VCC VBAT 5 VCC Rx 4 C7 0.1µF BATTERY CELLS RA (KΩ) thermistor battery’s temperature. The thermistor is inherently Thermistor Fig. 3 VTS AIC1781 Ry 12 GND Fig. 4 Battery Temperature Sense Circuit with resistance of RA and RB for the corresponding a number of battery cells are as below: (NTC) Thermistor Negative Temperature Coefficient 10 AIC1781 Power ON LED Flash 3 Times If VBT in Normal Range No Yes Yes If VNTC<0.72 VCC LED's Display Abnormal, ICON ON, Safety Timer Reset No If SEL3>VCC-0.3V or VCC/2-0.4V>SEL3 >1.4V No No If SEL3>VCC-0.3V or VCC/2-0.4V>SEL3 >1.4V Yes ∆T/∆t Disabled No Yes If VNTC>0.29VCC LED's Display, Abnormal, ICON ON, Safety Timer Reset Yes No If Discharge Finished If Discharge Enabled Yes Yes Battery Replacement Yes No No LED's Display Fast Charge, ICON OFF Safety Timer Counts ∆T/∆t Detector, -∆V Detector, Peak timer are all Disabled If Initial Timer Finished No Yes If Peak Timer Period has Finished Yes No If 0.25% Decline of VBT is Detected Yes No If ∆T/ ∆=t has Reached LED's Display Battery Fulll, Fast Charge Finished, Trickle charge Starts Battery Replacement Yes Yes No No No If Safety Timer Period has Finished Fig. 2 Yes Function Flow Chart of AIC1781 11 AIC1781 The calculation for Rx and Ry in the circuit is as 66 5.7 31.6 following. 67 5.5 29.5 68 5.3 27.5 69 5.2 25.8 70 5.0 24.3 0.29 VCC = Ry//RTH x VCC Rx + (Ry// RTH) RTH= The resistance of thermistor at upper limit of temperature protection. 0.72 VCC = TABLE. 2 Values of Rx and Ry at TL = -10°C Ry//R TL x VCC Rx + (Ry// R TL ) TH (°C) Rx (KΩ) Ry (KΩ) 45 11.4 95.6 46 11.0 85.0 47 10.6 76.2 48 10.2 68.9 49 9.8 62.8 50 9.5 57.5 5. 3 × RTL × RTH 51 9.1 52.9 RTL − 6. 3RTH 52 8.8 48.8 53 8.5 45.3 54 8.2 42.1 55 7.9 39.4 RTL= The resistance of thermistor at lower limit of temperature protection. Substitution and rearranging the equations yield Rx= 2.061 × Ry = RTL × RTH RTL − RTH If temperature characteristic of the thermistor is like that of SEMITEC 103AT-2, the resistance of Rx and Ry is tabulated for different TL and TH as below. 56 7.6 36.8 (Note: TL is lower temperature limit and TH is upper temperature limit.) 57 7.4 34.6 58 7.1 32.5 TABLE. 1 Values of Rx and Ry at TL = 0°C 59 6.9 30.7 TH (°C) Rx(KΩ) Ry (KΩ) 60 6.7 29.0 50 10.1 551.1 61 6.4 27.4 51 9.7 300.7 62 6.2 26.0 52 9.4 204.8 63 6.0 24.6 5.8 23.4 5.6 22.2 53 9.0 153.9 64 54 8.7 122.8 65 55 8.4 101.8 Setting the ADJ Pin Voltage 56 8.1 86.5 The slope of ∆T/∆t detection is determined by ADJ 57 7.8 75.0 58 7.5 66.0 pin voltage of the AIC1781. 59 7.2 58.7 60 7.0 52.8 61 6.8 47.8 62 6.5 43.6 63 6.3 39.9 64 6.1 36.8 65 5.9 34.0 The calculation of ADJ pin voltage is shown in the following procedure followed by an example. 12 AIC1781 Procedure (d) VADJ =25 x 0.043x 0.0166 x 56 = 1(V) If the temperature range is from 0°C to 50°C, the voltage of VADJ under different setting conditions should be set as tabulated below. (a) First, determine the temperature protection limits TH and TL. Then, substitute TH & TL into the following equation: ∆V TS 0.72 V CC − 0.29 V CC 0.43 V CC = = ∆TBASE TH − TL TH − TL (b) Determine the safety timer to obtain the value of ∆tBASE . ∆t BASE(sec.) = 56 (sec. ) × Safety Timer (min. ) 80(min. ) (c) Determine the expected slope of ∆T / ∆t at TABLE. 3 ADJ pin Voltage (TL=0°C, TH=50°C) ∆T / ∆t 0.75 S.T. (°C/min.) (°C/min.) (°C/min.) 40 min. (2C) 0.37 0.5 0.63 80 min. (1C) 0.75 1.0 1.25 120 min. (0.67C) 1.12 1.5 1.87 160 min. (0.5C) 1.5 2.0 2.5 200 min. (0.4C) 1.87 2.5 3.12 240 min. (0.33C) 2.25 3.0 3.75 60°C is as below. fast charge is subsequently cut off. TABLE. 4 ADJ Pin Voltage (TL=0°C, TH=60°C) ∆T / ∆t 0.75 S.T. (d) Calculate the value of VADJ V ADJ = 25 × ∆V TS ∆T × × ∆t BASE ∆TBASE ∆t Example (a) Let TH=50°C, TL=0°C, VCC =5V. We have ∆VTS 0.43 × 5 = = 0.043V/° C ∆TBASE 50 − 0 which means that VTS decreases 43mV as 1.25 A similar table for temperature range from 0°C to which temperature rises y°C in x seconds and ∆T y = ∆t x 1.0 1.0 1.25 (°C/min.) (°C/min.) (°C/min.) 40 min. (2C) 0.31 0.42 0.52 80 min. (1C) 0.62 0.84 1.05 120 min. (0.67C) 0.94 1.25 1.56 160 min. (0.5C) 1.25 1.67 2.08 200 min. (0.4C) 1.56 2.08 2.60 240 min. (0.33C) 1.87 2.5 3.12 VBT Range and Temperature Protection The acceptable voltage range of VBT pin and mode of temperature protection function is determined by the voltage of SEL3 pin, shown as the following: temperature rises 1°C. (b) If safety timer is equal to 80 minutes, ∆tBASE is then 56 seconds. (a) SEL3 > VCC - 0.3V Acceptable VBT Range: (c) If fast charge should be terminated when Before initial timer: 0.16V~2.7V temperature rises 1°C in 60 seconds, then ∆T/∆t = 1 = 0.0166 60 After initial timer: 0.69V~2.7V Temperature Protection Mode: Entering charge-suspending mode when 13 AIC1781 temperature is either too low or too high, Setting the Period of Safety Timer same as abnormal battery voltage. Latch for The AIC1781 provides a method for linearly charge-suspending function is provided for high temperature protection, but not for low temperature protection. adjusting the period of safety timer with an external resistor connected from TMR pin to GND. The relation between safety timer length and the external resistor (RTMR) is shown in Fig. 5. The (b) VCC - 1.4V> SEL3 > V cc - 0.4V 2 table following shows the resistor values for some of the commonly chosen safety timer periods. Also shown in the table are their corresponding oscillator Acceptable VBT Range: Before initial timer: 0.16V~2.7V frequencies. After initial timer: 0.69V~2.7V 800 Temperature Protection Mode: 600 regarded as completed. If temperature is too low, function of ∆T/∆t detection is disabled, just as thermistor is not existing. (c) RTMR (KΩ) If temperature is too high, battery charging is 400 200 V cc - 0.4V>SEL3 >1.4V 2 0 0 100 200 300 400 500 Safety Timer (min.) Acceptable VBT Range: Fig. 5 Before initial timer: 0.16V~2V After initial timer: 1.2V~2V Safety Timer vs RTMR when 11 OSC. Freq.(KHz) 262.4 temperature is either too low or too high, same 23 131.2 20 as abnormal battery voltage. Latch for charge- 48 65.6 40 suspending 74 43.7 60 100 32.8 80 152 21.9 120 206 16.4 160 314 10.9 240 Before initial timer: 0.16V~2V 491 7.3 360 After initial timer: 1.2V~2V 667 5.5 480 RTMR (KΩ) Temperature Protection Mode: Entering charge-suspending function temperature is protection, mode provided for high but for low not temperature protection. (d) 0.3V> SEL3 Acceptable VBT Range: Safety timer (min.) 10 Temperature Protection Mode: If temperature is too high, battery charging is Selecting Mode of Operation regarded as completed. If temperature is too low, The AIC1781 provides three modes of operation: function of ∆T/∆t detection is disabled, just as normal, test, and AC mode determined by the thermistor is not existing. setting of MODE pin according to TABLE 5. The AIC1781 will operate normally when the MODE pin is left floating (a 0.1µF capacitor is recommended 14 AIC1781 to be tied to MODE pin if the charge circuit works in SEL2 pins, the outputs of LED1 and LED2 pins a noisy environment). When the MODE pin is are shown in the following table: biased to GND, the function of -∆V detection is TYPE 1 disabled. When the MODE pin is biased to VCC, Power ON the AIC1781 enters the test mode. The test mode Fast Charge Fault Completed Conditions Charging can be used to significantly reduce production test LED1 1Hz ON OFF OFF time. For relevant informations please contact AIC LED2 OFF OFF ON OFF directly. TYPE 2 TABLE. 5 MODE pin Mode VCC Test Floating Power ON The Operating Mode of AIC1781 Function Safety timer period scaled down to 1/32....etc. Normal Normal operation GND AC –∆V detection disabled Fast Charge Fault Charging Completed Conditions LED1 1Hz ON OFF 4Hz Flashing LED2 1Hz 4Hz Flashing ON OFF Charging Current Control The Mode of LED Display and Trickle Charge As shown in the typical application circuit, the The AIC1781 provides two LED display modes AIC1781 offers an open-drained output pin, ICON and five-pulsed trickle charge modes. The tri-level pin, to control the charging current flow in fast inputs, SEL1 and SEL2 pins, as in the TABLE 6 charge state and switch on to inhibit the charging determine the modes of LED display and trickle current flow in fault conditions. When fast charge is charge. completed, the AIC1781 enters the trickle charge TABLE. 6 Mode of LED Display and Trickle Charge mode. In trickle charge mode, the ICON pin output SEL1 VCC Floating GND SEL2 Trickle Charge LED Display Duty Mode switches with predetermined duty cycle. Refer to the table of trickle charge mode (TABLE 6), the duty cycle is determined by the setting of SEL1 and VCC N/A Type 1 SEL2 pins. The following table summarizes how Floating 1/32 Type 1 GND 1/64 Type 1 ICON pin corresponds to various charging states. VCC 1/128 Type 1 Floating 1/256 Type 1 GND N/A Type 2 VCC 1/32 Type 2 Floating 1/64 Type 2 GND 1/128 Type 2 Power ON ICON ON Fast Charge Fault Charging Completed Conditions OFF See pin 10 & 11 ON Test Mode Fig. 6 shows the timing diagram for externally controlled PEAK, ADJ, VBT, VTS, SEL1 and Display the Battery Charging Status SEL2 pin voltages of a recommended AIC1781 The AIC1781 provides two open-drained outputs, test scheme, utilizing TEST mode function. LED1 and LED2, to indicate the battery charging Output waveforms of LED1, LED2 and ICON of a status. Refer to the table of LED display mode properly functioning AIC1781 are also shown in (TABLE 6), depending on the setting of SEL1 and the figure. 15 AIC1781 TIMING DIAGRAM VCC, SEL3, MODE=5V, (DSW FREQ.=820KHz, 25 TIMES of 32.8K) Power Init. ON -∆V TEST PEAK TIMER TEST 5V PEAK -∆V DISALBE TEST 0V 5V ADJ SAFETY TIMER TEST ∆T/∆t TEST 1.12V 3V <2.1V (-0.15%) 1.95V 2V VBT 2V (-0.15%) 1.997V 1.997V 2V 1.9V 1.5V 2mV Step/100mS 1.993V (-0.35%) 4V 4V 2V 2V 1.96V 0V 1.85V (-2.15%) (-2.5%) 2V 2mV Step/100mS OFF OFF OFF OFF 4V 4V 2V VTS 2V 1.997V ON ON ON LED1 OFF 3.2KHz LED2 ON OFF ICON SEL1 SEL2 TIME ON ON 0.1 0.14 0.12 Floating Floating 0.28 0.2 0.12 3 4 STAGE 2 0.32 0 0.14 0.26 0.54 0.74 0.86 ON Floating GND 0.32 0.12 5 6 0.32 1.18 Fig. 6 1.5 GND Floating 0.5 0.7 (SEC.) 1 OFF OFF VCC Floating 0.24 7 1.62 1.94 ON 2.64 GND GND 0.4 2.14 8 9 3.14 3.38 3.78 Floating Floating 0.1 0.02 10 5.92 6.02 6.04 Timing Diagram of AIC1781 in Test Mode 16 AIC1781 PHYSICAL DIMENSIONS 16 LEAD PLASTIC DIP (unit: mm) D SYMBOL MIN MAX A1 0.381 — A2 2.92 4.96 b 0.35 0.56 C 0.20 0.36 D 18.66 19.69 E 7.62 8.26 E1 6.09 7.12 E1 E A2 A1 C L e eB b eB — 10.92 L 2.92 3.81 16 LEAD PLASTIC SO (300 mil) (unit: mm) D E H A B SYMBOL MIN MAX A 2.35 2.65 A1 0.10 0.30 B 0.33 0.51 C 0.23 0.32 D 10.10 10.50 E 7.40 7.60 e e A1 e 2.54(TYP) c L 1.27(TYP) H 10.00 10.65 L 0.40 1.27 17