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AIC1781
Battery Charge Controller
FEATURES
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.
DESCRIPTION
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.
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APPLICATIONS
Battery Fast Chargers for: Mobile Phones. Notebook and Laptop Personal Computers. Portable Power Tools and Toys. Portable Communication Equipments. Portable Video & Stereo Equipments.
1.55 100
Charge Current = 600 mA Cell Capacity = 550 mA NiMH Battery
Cell Voltage
1.35
60
1.25
40
Temperature
1.15 0 10 20 30 40 50 60 20
Charge Time (min.)
Fig. 1 Battery Charging Characteristics Resulting from an AIC1781-Controlled Charger with a Fluctuating Charging Current
Analog Integrations Corporation DS-1781-00
4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC TEL: 886-3-5772500 FAX: 886-3-5772510
Temperature (C)
Cell Voltage (V)
1.45
80
1
AIC1781
TYPICAL APPLICATION CIRCUIT
D1 R1 1K IN4148 C2 1F R5 120/0.5W U1 R4 390K 1 2 3 C1 1000P AIC1563 4 DC DE CF GND BOOST IS 6 VCC 5 FB + C3 BAT1 R7 THERMISTOR RY1 100K 8 7 D3 IN4148 R6 0.3/1W RX1 100K C6 0.1F + 2N3904 C8 R14 R18 200K 50K R11 100K L1 220H + C5 C4 220F D2 IN4148 R3 R2 20/5W LED1 R9 240K + R8 120K C9 R10 100K YELLOW 1 2 C10 47nF R15 Q1 680 VBT 3 DIS 4 VTS 5 VCC 6 7 8 ADJ SEL3 TMR SW PB 270 R12 100K 16 15 14 13 12 11 10 9 R16 680 R17 680 GREEN RED SW1 LED2 LED3
U2 PEAK
DSW ICON LED2 LED1 GND SEL1 SEL2 MODE
0.1F
D4
1N5819
4.7F
C7 0.1F
220F
C11
100F R13
0.1F
AIC1781
BATTERY
VIN 1
+
U3 VIN
7805 VOUT 2 GND 3
+
470K Q2 2N3904 C13 10F
C12 1uF
Battery Charge Circuit for Fluctuating Charging Current Application
ORDERING INFORMATION
AIC1781XX PACKAGE TYPE N: PLASTIC DIP S: SMALL OUTLINE TEMPERATURE RANGE C= 0C~70C AIC1781CS (PLASTIC SO) ORDER NUMBER AIC1781CN (PLASTIC DIP) PIN CONFIGURATION
PEAK 1 VBT 2 16 DSW 15 ICON 14 LED2 13 LED1 12 GND 11 SEL1 10 SEL2 9 MODE
DIS 3 VTS VCC ADJ 4 5 6
SEL3 7 TMR 8
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 .................................................................. 0C~ 70C Storage Temperature Range ............................................................... -65C~ 150C
2
AIC1781
TEST CIRCUIT
VCC VOLTAGE SOURCE + YELLOW R1 560 PEAK VBT DIS DSW R3 ICON LED2 560 R4 560 R5 560 VCC VCC VCC VCC RED GREEN ORANGE
-
+
VTS VCC ADJ SEL3
VOLTAGE SOURCE VCC (5V) VCC V1 (0.95V) V2 (3V) 100K R2
AIC1781
LED1 GND SEL1 SEL2 MODE
TMR
ELECTRICAL CHARACTERISTICS (Ta=25C, VCC=5V, unless otherwise specified.)
PARAMETER Supply Voltage Supply Current Voltage Protection Limit Battery Low During Initial Timer After Initial Timer (SEL3>3V) (SEL3<2V) Battery High (SEL3>3V) (SEL3<2V) TEST CONDITIONS SYMBOL VCC ICC MIN. 4.5 TYP. 5.0 1.1 MAX. 5.5 UNIT V mA
0.11 0.63 1.1 2.6 1.9
0.16 0.69 1.2 2.7 2.0
0.21 0.75 1.30 2.80 2.10 V
VBT
3
AIC1781
ELECTRICAL CHARACTERISTICS
PARAMETER TEST CONDITIONS Temperature High Temperature Sense Limit Output impedance of DIS Pin Temperature Low
(Ta=25C, VCC=5V, unless otherwise specified.) SYMBOL MIN. 1.35 VTS ZDIS 3.5 TYP. 1.45 3.6 140 MAX. 1.55 3.70 250 UNIT V
Output Impedance
LED1, LED2, ICON Pins ON OFF SEL3 pin DSW pin MODE, PEAK, SEL1, SEL2 pins VBT, VTS, ADJ pins ISEL3 IDSW
25 1 5.5 16
50
M
Source Current Capability
A
Input Impedance
300 1 RTMR 2 100 1000
K M K
Recommended External Resistor of TMR pin -V Detection Level w.r.t.* Peak Value
-0.25
%
TYPICAL PERFORMANCE CHARACTERISTICS
VCC=5V, refer to Test Circuit)
(Ta=25C, R2=100K,
Supply Current vs Supply Voltage
1.21 1.18 81.0
Safety Timer vs Supply Volatge
Supply Current (mA)
Safety Timer (min.)
4.6 4.8 5.0 5.2 5.4
80.5
1.12
80.0
1.06
79.5
1.00 4.4 79.0 4.4 4.6 4.8 5.0 5.2 5.4
VCC (V)
VCC (V)
4
AIC1781
TYPICAL PERFORMANCE CHARACTERISTICS
LED Flashing Frequency vs Supply Voltage
4.8 1.26 4.6
(Continued)
Supply Current vs Temperature
Supply Current (mA)
Frequency (Hz)
4.4
1.14
4.2
1.02
4.0
3.8 4.4 4.6 4.8 5.0 5.2 5.4
0.9 0 20 40 60 80
VCC (V)
Temperature (C)
Safety Timer vs Temperature
5.0 82.0
LED Flashing Frequency vs Temperature
4.6
Safety Timer (min.)
81.0
Frequency (Hz)
0
4.2
80.0 3.8
79.0
20
40
60
80
3.4 0
20
40
60
80
Temperature(C)
Temperature(C)
VBT (high) Limit vs Temperature (SEL3>3V)
2.74
VBT (high) Limit vs Temperature (SEL3<2V)
2.03
2.70
VBT (V)
VBT (V)
2.66 2.62
2.01
1.99
1.98
0 20 40 60 80
0
20
40
60
80
Temperature (C)
Temperature (C)
5
AIC1781
TYPICAL PERFORMANCE CHARACTERISTICS
(Continued)
VBT (low) Limit vs Temperature (During Initial Timer)
0.163 29
Output Impedance vs Temperature (LED1,LED2,ICON pins)
0.162
Output Impedance()
0 20 40 60 80
27
VBT (V)
0.161
0.160
25
0.159
0.158
23 0 20 40 60 80
Temperature (C)
Temperature (C)
VTS (high) Limit vs Temperature
1.48 3.62
VTS (low) Limit vs Temperature
3.61
1.46
VTS (V)
3.60
3.59
3.58
0
20
Temperature (C)
40
60
80
VTS (V)
1.44 1.42 0
20
Temperature (C)
40
60
80
VBT(LOW) Limits vs Temperature (SEL3>3V, After Initial Timer)
0.700 1.24
VBT(LOW) Limits vs Temperature (SEL3<3V, After Initial Timer)
0.695
VBT(V)
0.690 1.20
0.685 1.18 60 80
VBT (V)
1.22
0
20
40
0
20
40
60
80
Temperature (C)
Temperature (C)
6
AIC1781
BLOCK DIAGRAM
PEAK MODE GND VCC TMR
Peak Voltage Timer Control
MODE Selection
Bandgap Reference & Voltage Regulator
LED2
Oscillator
SEL3
Battery Voltage & Temperature Portection Setting
LED1
Charge Control
SEL1 SEL2 ADJ
LED`s Display & Trickle Pulse Duty Setting T/t Detection Setting Battery Voltage Protection
Display Control Unit
State Machine
ICON
Charge Control Unit
DIS
13-bit A/D Discharge Control Unit
Battery Temp. Protection
DSW
VTS
VBT
PIN DESCRIPTIONS
PIN 1: PEAK- Tri-level input, determining the period of peak voltage timer. (See 0V cut-off section in application informations.) PIN 2: VBTPIN 3: DISDivided battery voltage input to sense the battery voltage. Push-pull output, used to control an external transistor to discharge the battery. DIS is active high when the AIC1781 enters discharge mode. PIN 4: VTSThe battery cell temperature is represented as a voltage input to the AIC1781 at this pin. The PIN 5: VCCPIN 6: ADJacceptable voltage range of VTS pin is 0.29 VCC to 0.72 VCC. The battery temperature is regarded as too high if the voltage of VTS pin is lower than 0.29 VCC, and is otherwise regarded as too low if the voltage of VTS pin is higher than 0.72 VCC. Power supply input at 5V10%. For adjusting the slope of T/t. Acceptable voltage range for this pin is approximately 0.28V to 3.8V. If voltage higher than
7
AIC1781
VCC-0.3V, the function of T/t detection is disabled.
PIN 9: MODE- Determine PIN 10: SEL2 &
the
mode
of
operation for the AIC1781. PIN 11: SEL1- Tri-level inputs, that jointly
PIN 7: SEL3-
Determine
the
acceptable
voltage range of VBT pin and mode of temperature protection function. PIN 8: TMRDetermine the period of safety timer with an external resistor connected to GND. PIN 12: GND-
control the LED display mode and the duty of trickle charge after the completion of fast charge. Power ground.
APPLICATION INFORMATIONS
THE AIC1781 OPERATION Power-on and Battery Pre-qualifying When power is first applied to the AIC1781, all internal digital circuit blocks of the AIC1781 are reset by the internal power-on-reset circuitry and output LEDs (depending on the setting of SEL1 and SEL2 pins) flash 3 times to indicate the initiation of poweron. The internal control unit then examines the battery condition through the VBT and VTS pins. The acceptable limits of VBT pin is determined by the input voltage of SEL3 pin and the acceptable 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. Discharge-Before-Charge The AIC1781 provides the function of dischargebefore-charge to precondition NiCd batteries which suffer from memory effect. This function can only be activated after the pre-qualification of battery voltage and temperature, yet before the charge completion 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 begins, LED1 and LED2 pins are both off, ICON pin is on, and DIS pin goes high to activate an external circuit to discharge the battery until the voltage of VBT pin falls below 0.9V (or 0.69V, depending on the input voltage of SEL3 pin) or DSW pin is biased to GND for over 0.18 second again. Fast charge will automatically start after discharge is finished. The application circuit is included in TYPICAL APPLICATION CIRCUIT. 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 stage of a charge cycle elapses. The initial timer period is equal to 1/80 of safety timer. Since the low limit of acceptable VBT voltage is only about 0.16V during the initial timer period, even deeply discharged batteries can easily qualify to be fast charged subsequently.
8
AIC1781
In the course of fast charge, the AIC1781 constantly monitors the voltages at VBT and VTS pins. The fast charge process is switched to trickle charge when any one of the following situations is encountered, which are explained below: Negative delta voltage (-V) Peak voltage timer (0 V ) Delta temperature/ delta time (T/t) Maximum charge time Maximum battery voltage Maximum battery temperature
-V Cutoff
Maximum Safety Timer Cutoff
The maximum fast charge period is determined by the safety timer, which is set by a resistor connected from TMR pin to GND. Safety timer, -V sampling rate, and T/t sampling rate will be longer if the resistor value is larger. When the value of the resistor is 100K, the safety timer period equals 80 minutes. This can be verified by biasing MODE pin to VCC and the measured frequency on DSW pin should be around 32.8 KHz. After the safety timer period is finished, the fast charge action is terminated.
Maximum Voltage and Temperature Cutoff
The AIC1781 makes a voltage sampling at VBT pin every 4 seconds when safety timer period is set equal to 80 minutes. If a negative delta voltage of 0.25% compared to its peak value is detected at VBT pin, the fast charge cycle is terminated.
0V Cutoff
The AIC1781 guards against the maximum limits for battery voltage and temperature during fast charging. If either of these limits is exceeded, fast charge action is terminated.
Trickle Charge
If the battery voltage stays at its peak value or decreases very slowly for the duration determined by the peak voltage timer, which is in turn determined by PEAK pin voltage, the fast charge action is terminated. T/t Cutoff The T/t detection of the AIC1781 is performed by sensing the decrease of VTS pin voltage in a specific timer interval dictated by the safety timer. The fast charging terminates when the decrease of VTS pin voltage in 56 seconds exceeds the predetermined value set by ADJ pin input. This time interval of 56 seconds is based on the assumption that voltage of VTS pin is sampled once for every 8 seconds, which is also determined by safety timer. Functioning of -V detection and peak voltage timer (0 V ) can be disabled if the MODE pin is biased to GND. Functioning of - 0.3V. T/t detection can be disabled if the voltage of ADJ pin is higher than VCC
There are five different selectable duty cycles for trickle charge after the fast charge to prevent the loss of charge due to battery self-discharging. The duty cycle is controlled by the setting of SEL1 and SEL2 pins. The functions and charging states control mentioned above are illustrated in the function flow chart of AIC1781 (Fig. 2)
DESIGN GUIDE Selecting Peak Voltage Timer (0V)
The voltage of PEAK pin along with safety timer determines the period of peak voltage timer. It can be selected according to the following table:
PEAK PIN PEAK VOLTAGE TIMER
VCC Floating GND
1.5% of safety timer 3.7% of safety timer 6% of safety timer
9
AIC1781
Battery Voltage Measurement
The AIC1781 measures the battery voltage through VBT pin, which is connected to battery positive terminal through a resistor-divider network, as shown in Fig. 3. The input voltage of SEL3 pin determines the acceptable limit of divided battery voltage.
VBAT RA R5 + C5 100K 4.7F C6 0.1F 2 VBT AIC1781
BATTERY CELLS 2 3 4 5 6 8 10 12 16
RA/RB
RA(K)
RB (K)
1 2 3 4 5 7 9 11 15
240 240 240 300 300 360 360 390 410
240 120 80 75 60 51 40 36 27
RB
Battery Temperature Measurement
The AIC1781 employs a negative temperature
Fig. 3 Battery Voltage Divider
coefficient (NTC)
thermistor
to measure the
battery's temperature. The thermistor is inherently 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.
VCC VBAT Rx 4 Thermistor C7 0.1F 5 VCC VTS
For SEL3 > (VCC/2) + 0.4V, the suggested divider resistance of RA and RB for the corresponding number of battery cells are as below: BATTERY CELLS 2~4 3~6 4~8 5~10 6~12 8~16 RA/RB 2 3.3 4.9 6.4 7.8 10.8 RA (K) 240 300 300 300 310 390 RB (K) 120 91 62 47 39 36
AIC1781
Ry 12 GND
For SEL3 < (VCC/2) - 0.4V, the suggested divider resistance of RA and RB for the corresponding number of battery cells are as below:
Fig. 4 Battery Temperature Sense Circuit with a Negative Temperature Coefficient (NTC) Thermistor
10
AIC1781
Power ON
LED Flash 3 Times
If VBT in Normal Range Yes If VNTC<0.72 VCC No Yes
No
LED's Display Abnormal, ICON ON, Safety Timer Reset Yes If SEL3>VCC-0.3V or VCC/2-0.4V>SEL3 >1.4V
No
No
T/t Disabled
If VNTC>0.29VCC
No
If SEL3>VCC-0.3V or VCC/2-0.4V>SEL3 >1.4V
Yes
LED's Display, Abnormal, ICON ON, Safety Timer Reset
Yes No If Discharge Finished Yes Yes If Discharge Enabled No LED's Display Fast Charge, ICON OFF Safety Timer Counts No
Battery Replacement
Yes
T/t Detector, -V Detector, Peak timer are all Disabled
No
If Initial Timer Finished Yes If Peak Timer Period has Finished No If 0.25% Decline of VBT is Detected No
Yes
Yes
LED's Display Battery Fulll, Fast Charge Finished, Trickle charge Starts
Battery Replacement
Yes
If T/ =t has Reached
Yes No
No If Safety Timer Period has Finished
No
Yes
Fig. 2
Function Flow Chart of AIC1781
11
AIC1781
The calculation for Rx and Ry in the circuit is as following. 0.29 VCC =
66 67 68 69 70
5.7 5.5 5.3 5.2 5.0
31.6 29.5 27.5 25.8 24.3
Ry//RTH x VCC Rx + (Ry// RTH)
RTH= The resistance of thermistor at upper limit of temperature protection. 0.72 VCC =
Ry//R TL x VCC Rx + (Ry// R TL )
TABLE. 2 Values of Rx and Ry at TL = -10C
TH (C) 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
Rx (K) 11.4 11.0 10.6 10.2 9.8 9.5 9.1 8.8 8.5 8.2 7.9 7.6 7.4 7.1 6.9 6.7 6.4 6.2 6.0 5.8 5.6
Ry (K) 95.6 85.0 76.2 68.9 62.8 57.5 52.9 48.8 45.3 42.1 39.4 36.8 34.6 32.5 30.7 29.0 27.4 26.0 24.6 23.4 22.2
RTL= The resistance of thermistor at lower limit of temperature protection. Substitution and rearranging the equations yield Rx= 2.061 x Ry = RTL x RTH RTL - RTH
5. 3 x RTL x RTH RTL - 6. 3RTH
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. (Note: TL is lower temperature limit and TH is upper temperature limit.)
TABLE. 1 Values of Rx and Ry at TL = 0C
TH (C) 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
Rx(K) 10.1 9.7 9.4 9.0 8.7 8.4 8.1 7.8 7.5 7.2 7.0 6.8 6.5 6.3 6.1 5.9
Ry (K) 551.1 300.7 204.8 153.9 122.8 101.8 86.5 75.0 66.0 58.7 52.8 47.8 43.6 39.9 36.8 34.0
Setting the ADJ Pin Voltage
The slope of T/t detection is determined by ADJ pin voltage of the AIC1781. The calculation of ADJ pin voltage is shown in the following procedure followed by an example.
12
AIC1781
Procedure
(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. ) x Safety Timer (min. ) 80(min. )
(d) VADJ =25 x 0.043x 0.0166 x 56 = 1(V) If the temperature range is from 0C to 50C, the voltage of VADJ under different setting conditions should be set as tabulated below.
TABLE. 3 ADJ pin Voltage (TL=0C, TH=50C)
T / t S.T. 40 min. (2C) 80 min. (1C) 160 min. (0.5C) 200 min. (0.4C)
0.75 0.37 0.75 1.5 1.87
1.0 0.5 1.0 1.5 2.0 2.5 3.0
1.25 0.63 1.25 1.87 2.5 3.12 3.75
(C/min.) (C/min.) (C/min.)
120 min. (0.67C) 1.12
240 min. (0.33C) 2.25
(c) Determine the expected slope of T / t at which temperature rises yC in x seconds and fast charge is subsequently cut off. T y = t x (d) Calculate the value of VADJ V ADJ = 25 x V TS T x x t BASE TBASE t
A similar table for temperature range from 0C to 60C is as below.
TABLE. 4 ADJ Pin Voltage (TL=0C, TH=60C)
T / t S.T. 40 min. (2C) 80 min. (1C) 120 min. (0.67C) 160 min. (0.5C) 200 min. (0.4C) 240 min. (0.33C)
0.75 0.31 0.62 0.94 1.25 1.56 1.87
1.0 0.42 0.84 1.25 1.67 2.08 2.5
1.25 0.52 1.05 1.56 2.08 2.60 3.12
(C/min.) (C/min.) (C/min.)
Example
(a) Let TH=50C, TL=0C, VCC =5V. We have VTS 0.43 x 5 = = 0.043V/ C TBASE 50 - 0 which means that VTS decreases 43mV as temperature rises 1C. (b) If safety timer is equal to 80 minutes, tBASE is then 56 seconds. (c) If fast charge should be terminated when temperature rises 1C in 60 seconds, then T/t = 1 = 0.0166 60
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: (a) SEL3 > VCC - 0.3V
Acceptable VBT Range: Before initial timer: 0.16V~2.7V 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, same as abnormal battery voltage. Latch for charge-suspending function is provided for high temperature protection, but not for low temperature protection.
Setting the Period of Safety Timer
The AIC1781 provides a method for linearly 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 table following shows the resistor values for some of the commonly chosen safety timer periods. Also shown in the table are their corresponding oscillator frequencies.
800
(b) VCC - 1.4V> SEL3 >
V cc - 0.4V 2
Acceptable VBT Range: Before initial timer: 0.16V~2.7V After initial timer: 0.69V~2.7V Temperature Protection Mode:
If temperature is too high, battery charging is
RTMR (K)
600
regarded as completed. If temperature is too low, function of T/t detection is disabled, just as thermistor is not existing.
400
200
(c)
V cc - 0.4V>SEL3 >1.4V 2
Acceptable VBT Range: Before initial timer: 0.16V~2V After initial timer: 1.2V~2V Temperature Protection Mode:
0 0 100 200 300 400 500
Safety Timer (min.)
Fig. 5
Safety Timer vs RTMR
RTMR (K) mode when 11 23 48 74 100 152 206 314 491 667
Entering
charge-suspending
OSC. Freq.(KHz) 262.4 131.2 65.6 43.7 32.8 21.9 16.4 10.9 7.3 5.5
Safety timer (min.) 10 20 40 60 80 120 160 240 360 480
temperature is either too low or too high, same as abnormal battery voltage. Latch for chargesuspending temperature function is provided but not for for high low protection,
temperature protection.
(d) 0.3V> SEL3 Acceptable VBT Range: Before initial timer: 0.16V~2V After initial timer: 1.2V~2V Temperature Protection Mode:
If temperature is too high, battery charging is regarded as completed. If temperature is too low, function of T/t detection is disabled, just as thermistor is not existing.
Selecting Mode of Operation
The AIC1781 provides three modes of operation: normal, test, and AC mode determined by the setting of MODE pin according to TABLE 5. The AIC1781 will operate normally when the MODE pin is left floating (a 0.1F capacitor is recommended
14
AIC1781
to be tied to MODE pin if the charge circuit works in a noisy environment). When the MODE pin is biased to GND, the function of -V detection is disabled. When the MODE pin is biased to VCC, the AIC1781 enters the test mode. The test mode can be used to significantly reduce production test time. For relevant informations please contact AIC directly.
TABLE. 5 The Operating Mode of AIC1781
SEL2 pins, the outputs of LED1 and LED2 pins are shown in the following table:
TYPE 1
Power ON LED1 LED2 1Hz OFF Charge Fault Completed Conditions Charging ON OFF OFF ON OFF OFF Fast
TYPE 2
Power ON LED1 LED2 1Hz 1Hz Fast Charge Fault Charging Completed Conditions ON 4Hz Flashing OFF ON 4Hz Flashing OFF
MODE pin VCC Floating GND
Mode Test
Function Safety timer period scaled down to 1/32....etc.
-V detection disabled
Normal Normal operation AC
Charging Current Control The Mode of LED Display and Trickle Charge
As shown in the typical application circuit, the AIC1781 offers an open-drained output pin, ICON pin, to control the charging current flow in fast charge state and switch on to inhibit the charging current flow in fault conditions. When fast charge is completed, the AIC1781 enters the trickle charge mode. In trickle charge mode, the ICON pin output 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 SEL2 pins. The following table summarizes how ICON pin corresponds to various charging states.
Power ON ICON ON Fast Charge Fault Charging Completed Conditions OFF See pin 10 & 11 ON
The AIC1781 provides two LED display modes and five-pulsed trickle charge modes. The tri-level inputs, SEL1 and SEL2 pins, as in the TABLE 6 determine the modes of LED display and trickle charge.
TABLE. 6 Mode of LED Display and Trickle Charge
SEL1 VCC
SEL2 VCC Floating GND VCC Floating GND
Trickle Charge LED Display Duty Mode N/A 1/32 1/64 1/128 1/256 N/A 1/32 1/64 1/128 Type 1 Type 1 Type 1 Type 1 Type 1 Type 2 Type 2 Type 2 Type 2
Floating
GND
VCC Floating GND
Test Mode
Fig. 6 shows the timing diagram for externally controlled PEAK, ADJ, VBT, VTS, SEL1 and SEL2 pin voltages of a recommended AIC1781 test scheme, utilizing TEST mode function. Output waveforms of LED1, LED2 and ICON of a properly functioning AIC1781 are also shown in the figure.
Display the Battery Charging Status
The AIC1781 provides two open-drained outputs, LED1 and LED2, to indicate the battery charging status. Refer to the table of LED display mode (TABLE 6), depending on the setting of SEL1 and
15
AIC1781
TIMING DIAGRAM
VCC, SEL3, MODE=5V, (DSW FREQ.=820KHz, 25 TIMES of 32.8K)
Power Init. ON PEAK TIMER TEST
-V TEST 0V
-V DISALBE TEST
T/t TEST
SAFETY TIMER TEST
PEAK
5V
ADJ 3V
5V
1.12V <2.1V
(-0.15%) 2V 1.95V 1.997V 2V (-0.15%) 1.997V 1.993V (-0.35%) 4V 2V 1.96V (-2.15%) 2V 1.997V 1.9V 2V 2mV Step/100mS
VBT
1.5V 2V VTS 0V
4V
4V 2V 1.85V (-2.5%) OFF ON 3.2KHz ON 2mV Step/100mS
4V 2V
OFF ON LED1 OFF LED2 OFF
ON
OFF
OFF
ON
ON OFF OFF ON
GND Floating 0.7
0.5 7 0.24 0.4 8
ON
ICON SEL1 SEL2 TIME
(SEC.)
VCC Floating
0.1 0.14 0.12 1 2 0.28 0.2 3 0.12 4
Floating Floating
0.32 0.32 5 0.12 6 0.32
Floating GND
GND GND
2.14 9
Floating Floating
0.1 0.02 10
STAGE
0 0.14 0.26
0.54
0.74 0.86
1.18
1.5
1.62
1.94
2.64
3.14 3.38
3.78
5.92 6.02
6.04
Fig. 6
Timing Diagram of AIC1781 in Test Mode
16
AIC1781
PHYSICAL DIMENSIONS
16 LEAD PLASTIC DIP (unit: mm)
D
SYMBOL A1
E1
MIN 0.381 2.92 0.35 0.20 18.66 7.62 6.09 -- 2.92
MAX -- 4.96 0.56 0.36 19.69 8.26 7.12 10.92 3.81
A2 b
E
C D E
C
A2 A1 L eB b e
E1 e eB L
2.54(TYP)
16 LEAD PLASTIC SO (300 mil) (unit: mm)
D
SYMBOL A A1
E H
MIN 2.35 0.10 0.33 0.23 10.10 7.40 10.00 0.40
MAX 2.65 0.30 0.51 0.32 10.50 7.60 10.65 1.27
B C D E
e A
e H
A1
1.27(TYP)
B
c
L
L
17

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