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SS6781A(G) Battery Charger Controller
FEATURES
Fast charge control of NiMH/NiCd batteries, even with a fluctuating charging current. Fast charge termination by: T/t, -V, 0V, safety timer, maximum temperature or 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 Packaged in SO-16 or PDIP-16
DESCRIPTION
The SS6781A fast charger controller IC is designed for intelligent charging of NiMH or NiCd batteries without the risk of overcharge. Using -V detection (-0.25%), 0V detection (peak voltage timer) and T/t detection are the primary methods employed by the SS6781A 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 SS6781A utilizes the combination of these two methods to reliably determine when to end fast charge and prevent mistakes caused by using - V detection alone under certain conditions. Fig. 1 shows an example of a charging curve for a battery charged by a fluctuating current from a NiMH battery charger, which uses the SS6781A controller IC to achieve optimal charging. This technique, in conjunction with the 0 V detection (peak voltage timer), is particularly suitable for NiMH batteries, whose voltage drop is hardly significant yet temperature T/ rises rapidly. The T/ tt or - V detection
This device is available with Pb-free lead finish.
APPLICATIONS
Fast Battery Chargers for: Mobile Phones. Notebook and Laptop Personal Computers. Portable Power Tools and Toys. Portable Communication Equipment. Portable Video and Stereo Equipment.
1.55 100
Charge Current = 600 mA Cell Capacity = 550 mA NiMH Battery
Temperature (C)
Cell Voltage (V)
1.45
80
circuitry
may
be
disabled
independently
for
Cell Voltage
1.35 60
different applications, such as system-integrated chargers, chargers with varying charge current, or battery packs which lack a temperature sensing thermistor.
1.25
40
Temperature
1.15 20 0 10 20 30 40 50 60
Charge Time (min.)
The safety timer period, battery temperature protection mode, battery voltage protection range, pulsed trickle charge duty, and LED display mode are all adjustable or selectable.
Fig. 1 Battery Charging Characteristics Resulting from a SS6781A-Controlled Charger with a Fluctuating Charging Current
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SS6781A(G)
Discharge-before-charge function is included to eliminate memory effects of NiCd batteries without the risk of overdischarging. Test mode is provided for charger manufactures to dramatically reduce production test time.
TYPICAL APPLICATION CIRCUIT
D1 R1 1K IN4148 C2 1F R5 120/0.5W U1 R4 390K 1 2 3 C1 470P SS6563 4 DC DE CF GND 8 BOOST 7 IS 6 VCC 5 FB + C3 D3 IN4148 RS 0.3/1W BAT1 **BATTERY RX
THERMISTOR
R3 R2 L1 220H + C5 C4 220F D2 IN5819 20/5W LED1 R8 300K + R9 91K C9 4.7F C7 0.1F R10 100K YELLOW 1 PEAK 2 C10 47nF Q1
MPS2222A
SW1 LED2 PB SW R12 100K DSW ICON LED2 LED1 GND SEL1 SEL2 MODE 16 15 14 13 12 11 10 9 R16 680 R17 680 GREEN RED LED3
270
U2
0.1F
R15 680
VBT 3 DIS 4 VTS 5 VCC 6 ADJ SEL3 TMR
D4
1N5819
R14 + 200K C11 C8 R6 50K R11
7 8
R7
220F
RY
C6 0.1F
100F R13 470K
0.1F
SS6781A
100K
VIN 11~15V
+
U3
78L05 VOUT
+
VIN C12 1F
Q2 MMBT2222A C13 10F
GND
**3~5 NiMH/NiCd cells. Note: Charge Current=0.3/RS Ampere Safety Timer: 80min
Battery Charge Circuit for Fluctuating Charging Current Application
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SS6781A(G)
ORDERING INFORMATION
SS6781AXXXX
Packing TR: Tape and reel TB: Tubes Package type N : PDIP-16 (only available in tubes) S: SO-16 C: Commercial grade G: , Commercial, with Pb-free lead finish (Available for SO-16 only) Example: SS6781ACSTR a in SO-16 shipped on tape and reel SS6781AGSTR a in SO-16 with Pb-free leads shipped on tape and reel TOP VIEW
PEAK VBT DIS VTS VCC ADJ SEL3 TMR 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 DSW ICON LED2 LED1 GND SEL1 SEL2 MODE
PIN CONFIGURATION
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
TEST CIRCUIT
VCC VOLTAGE SOURCE + YELLOW R1 560 PEAK VBT DIS DSW R3 ICON LED2 560 R4 560 VTS LED1 R5 560 GND VCC ADJ SEL3 100K R2 TMR SEL1 SEL2 MODE VCC VCC VCC RED GREEN ORANGE
-
+
VOLTAGE SOURCE VCC VCC (5V) VCC V1 (0.95V) V2 (3V)
SS6781A
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ELECTRICAL CHARACTERISTICS (TA=25C, VCC=5V, unless otherwise specified.)
PARAMETER Supply Voltage Supply Current Battery Low During Initial Timer After Initial Timer (SEL3>3V) (SEL3<2V) Battery High (SEL3>3V) (SEL3<2V) Temperature High Temperature Sense Limit Output impedance of DIS Pin LED1, LED2, ICON pins Output Impedance ON OFF SEL3 pin Source Current Capability DSW pin MODE, PEAK, SEL1, SEL2 pins VBT, VTS, ADJ pins Recommended External Resistor of TMR pin -V Detection Peak Value Level w.r.t.* RTMR 2 100 1000 k 1 ISEL3 IDSW 1 5.5 90 25 50 M A Temperature Low VTS ZDIS 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 1.35 3.5
0.16 0.69 1.2 2.7 2.0 1.45 3.6 50
0.21 0.75 1.30 2.80 2.10 1.55 V 3.70 100
Voltage Protection Limit
VBT
V
Input Impedance
300
k M
-0.25
%
* w.r.t.: with respect to
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TYPICAL PERFORMANCE CHARACTERISTICS
(TA=25C, R2=100k , VCC=5V, refer to test circuit)
1.08
81.5 81.0
Supply Current (mA)
1.02
Safety Timer (min)
4.6 4.8 5.0 5.2 5.4
80.5 80.0 79.5 79.0 78.5
0.96
0.90
0.84 4.4
78.0 4.4
4.6
4.8
5.0
5.2
5.4
5.6
VCC (V) Fig. 2 Supply Current vs. Supply Voltage
VCC (V) Fig. 3 Safety Timer vs. Supply Voltage
4.4
1.05
Supply Current (mA)
1.00
Frequency (Hz)
4.2
0.95
4.0
0.90
3.8
0.85
3.6 4.4
4.6
4.8
5.0
5.2
5.4
5.6
0.80 0
20
40
60
80
VCC (V) Fig. 4 LED Flashing Frequency vs. Supply Voltage
82 81 5.0 4.8
Temperature (C) Fig.5 Supply Current vs. Temperature
Safety Timer (min)
80 79 78 77 76 75 0 20 40 60 80
Frequency (Hz)
4.6 4.4 4.2 4.0 3.8 3.6 3.4 -20
0
20
40
60
80
Temperature (C) Fig. 6 Safety Timer vs. Temperature
Temperature (C) Fig. 7 LED Flashing Frequency vs. Temperature
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TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
2.80 2.28
2.76 2.16
VBT (V)
2.72
VBT (V)
0 20 40 60 80
2.68
2.04
2.64 1.92 2.60 0 20 40 60 80
Fig. 8
Temperature (C) VBT (High) Limit vs. Temperature (SEL3>3V)
Fig. 9
Temperature (C) VBT (High) Limit vs. Temperature (SEL3<2V)
0.20
33
0.18
Output Impedance ()
0 20 40 60 80
30
VBT (V)
0.16
27
0.14
24
0.12
21 0 20 40 60 80
Fig.10
Temperature (C) VBT (Low) Limit vs. Temperature (During Initial Timer)
Temperature (C) Fig.11 Output Impedance vs. Temperature (LED1, LED2, ICON Pins)
1.55
4.0
3.8
1.50
3.6
3.4
3.2
0
20
40
60
80
VTS (V)
VBT (V)
1.45
1.40
1.35
0
20
40
60
80
Fig.12
Temperature (C) VTS (Low Temp) Limit vs. Temperature
Temperature (C) Fig.13 VTS (High Temp) Limit vs. Temperature
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SS6781A(G)
1.5
0.84
1.4
0.80
VBT (V)
0 20 40 60 80
VBT (V)
0.76
1.3
0.72
1.2
0.68
1.1
0.64 1.0 0 20 40 60 80
Temperature (C) Fig. 14 VBT (Low) Limit vs. Temperature (SEL3>3V, After Initial Timer)
Fig.15
Temperature (C) VBT (Low) Limit vs. Temperature (SEL3<2V, After Initial Timer)
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
Display Control Unit
Charge Control
SEL1 SEL2
LED` Display s & Trickle Pulse Duty Setting T/t Detection Setting Battery Voltage Protection
ICON
State Machine
Charge Control Unit
ADJ
DIS
13-bit A/D Discharge Control Unit
Battery Temp. Protection
DSW
VTS
VBT
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SS6781A(G)
PIN DESCRIPTIONS
PIN 1: PEAK- Tri-level input, determining the period of peak voltage timer. (See 0V cut-off section in Application Information.) PIN 2: VBTDivided battery voltage input to sense the battery voltage. PIN 3: DISPush-pull output, used to PIN 8: TMRDetermines the period of safety timer with an external resistor connected to GND. PIN 9: MODE- Determines the mode of operation for the SS6781A. PIN 10: SEL2 - Tri-level inputs, that jointly
control the LED display mode and the duty of trickle charge after the completion of fast charge. PIN 11: SEL1- The same as Pin 10. PIN 12: GNDPower ground.
control an external transistor to discharge the battery. DIS is active-high when the SS6781A enters discharge mode.
PIN 4: VTS-
The battery cell temperature is represented as a voltage input to the SS6781A at this pin. The acceptable voltage range of VTS pin is 0.29VCC to 0.72Vcc The battery temperature is regarded as too high if the voltage of VTS pin is lower than 0.29V CC, and is otherwise regarded as too low if the voltage of the VTS pin is higher than 0.72VCC. PIN 13: LED1 & PIN 14: LED2- Open-drain outputs used to indicate the battery charging status. Two modes of display are available, depending on the setting of SEL1 and SEL2 pins. PIN 15: ICON- Open-drain output, used to control the charging current to the battery. PIN 16: DSW- Controlling the function of
PIN 5: VCCPIN 6: ADJ-
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 higher than VCC-0.3V, then T/t detection is disabled.
discharge-before-charge. (See discharge-before-charge subsection in Application Information).
PIN 7: SEL3-
Determines the acceptable voltage range of VBT pin and mode of temperature protection function.
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SS6781A(G)
APPLICATION INFORMATION
OPERATION OF THE SS6781A Power-on and Battery Pre-qualifying When power is first applied to the SS6781A, all internal digital circuit blocks of the SS6781A 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 power-on. The internal control unit then examines the battery condition through the VBT and VTS pins. The acceptable limits of VBT pin are 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 SS6781A 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 SS6781A is determined by the input voltage of SEL3 pin. Discharge-Before-Charge The SS6781A provides to the function of NiCd the discharge-before-charge function can only be precondition activated 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 SS6781A 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. In the course of fast charge, the SS6781A 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: l Negative delta voltage (-V) l Peak voltage timer ( 0 V ) l Delta temperature/ delta time (T/t) l Maximum charge time l Maximum battery voltage l Maximum battery temperature -V Cutoff The SS6781A 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 If the battery voltage stays at its peak value or decreases very slowly for the duration determined
batteries which suffer from memory effect. This pre-qualification of battery voltage and temperature, but 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
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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 SS6781A 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. GND 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 SS6781A 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 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 Fig. 17 Battery Voltage Divider
RB + C5
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 the SS6781A (Fig. 16)
l 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: TABLE 1 PEAK PIN VCC Floating PEAK VOLTAGE TIMER 1.5% of safety timer 3.7% of safety timer 6% of safety timer
T/t
detection can be
disabled if the voltage of ADJ pin is higher than VCC
Battery Voltage Measurement The SS6781A measures the battery voltage through VBT pin, which is connected to battery positive terminal through a resistor-divider network, as shown in Fig. 17. The input voltage of SEL3 pin determines the acceptable limit of divided battery voltage.
VBAT RA R5 100K 4.7F C6 0.1F SS6781A 2 VBT
For SEL3 > (VCC/2) + 0.4V, the suggested divider resistance of RA and RB for the corresponding number of battery cells are as below:
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TABLE 2 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
VBAT VCC 5 VCC 4 Thermistor 0.1F C7 VTS
Battery Temperature Measurement The SS6781A employs a negative temperature coefficient (NTC) thermistor to measure the battery' temperature. The thermistor is inherently s 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. 18.
For SEL3 < (VCC/2) -0.4V, the suggested divider resistance of RA and RB for the corresponding number of battery cells are as below: TABLE 3 BATTERY CELLS 2 3 4 5 6 8 10 12 16 RA/RB 1 2 3 4 5 7 9 11 15 RA(K) 240 240 240 300 300 360 360 390 410 RB (K) 240 120 80 75 60 51 40 36 27
Rx
SS6781A
Ry 12 GND
Fig. 18 Battery Temperature Sense Circuit with a Negative Temperature Coefficient (NTC) Thermistor
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SS6781A(G)
Power ON
LED Flash 3 Times
If VBT in Normal Range 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
If VNTC<0.72 VCC No Yes
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 If Discharge Enabled Battery Replacement No LED's Display Fast Charge, ICON OFF Safety Timer Counts No Yes
Yes
If Initial Timer Finished T/t Detector, -V Detector, Peak timer are all Disabled No 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. 16
Function Flow Chart of SS6781A
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65 The calculation for Rx and Ry in the circuit is as following. 66 67 68 69 70 5.9 5.7 5.5 5.3 5.2 5.0 34.0 31.6 29.5 27.5 25.8 24.3
Ry//RTH 0.29 VCC = x VCC Rx + (Ry// RTH)
RTH= The resistance of thermistor at upper limit of temperature protection. Ry//R TL 0.72 VCC = x VCC Rx + (Ry// R TL ) RTL= The resistance of thermistor at lower limit of temperature protection. Substitution and rearranging the equations yield Rx= 2.061 x Ry =
TABLE 5 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 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 4 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 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 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
Setting the ADJ Pin Voltage The slope of T/t detection is determined by the ADJ pin voltage of the SS6781A. The calculation of ADJ pin voltage is shown in the following procedure, followed by an example.
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Procedure
(a) First, determine the temperature protection limits TH and TL. Then, substitute TH & TL into the following equation: VTS 0.72V CC - 0.29V CC 0.43V CC = = TBASE TH - TL TH - TL (b) Determine the safety timer to obtain the value of tBASE . 56(sec.) tBASE(sec.) = x Safety Timer (min .) 80(min .) (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 VTS T VADJ = 30 x x x tBASE TBASE t TABLE 6 S.T. 40 min. (2C) 80 min. (1C) 120 min. (0.67C) 160 min. (0.5C) 200 min. (0.4C) 240 min. (0.33C) ADJ pin Voltage (TL=0C, TH=50C) 0.75 1.0 1.25 (C/min.) (C/min.) (C/min.) 0.45 0.60 0.75 0.90 1.35 1.80 2.25 2.70 1.20 1.80 2.40 3.01 3.61 1.50 2.25 3.01 3.76 4.51 T / t
A similar table for temperature range from 0C to 60C is as below. TABLE 7 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 1.0 1.25 (C/min.) (C/min.) (C/min.) 0.37 0.50 0.62 0.75 1.12 1.50 1.88 2.25 1.00 1.50 2.00 2.50 3.01 1.25 1.88 2.50 3.13 3.76
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 1 T/t = = 0.0166 60 (d) VADJ =30 x 0.043x 0.0166 x 56 = 1.2(V) If the temperature range is from 0C to 50C, the voltage of VADJ under different setting conditions should be set as tabulated below.
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 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.
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SS6781A(G)
(b) VCC - 1.4V> SEL3 >
V cc + 0.4V 2
of the commonly chosen safety timer periods. Also shown in the table are their corresponding oscillator frequencies.
800
Acceptable VBT Range: Before initial timer: 0.16V~2.7V After initial timer: 0.69V~2.7V
600
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.
RTMR (K)
400
200
0 0 100 200 300 400 500
V cc (c) - 0.4V>SEL3 >1.4V 2
Acceptable VBT Range: Before initial timer: 0.16V~2V After initial timer: 1.2V~2V Temperature Protection Mode: Entering as charge-suspending battery protection, mode when for low temperature is either too low or too high, same abnormal voltage. but not Latch for charge-suspending function is provided for high temperature 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. Setting the Period of Safety Timer The SS6781A 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. 19. The table following shows the resistor values for some
Safety Timer (min.)
Fig. 19 TABLE 8 RTMR (k) 11 23 48 74 100 152 206 314 491 667 OSC. Freq.(KHz) 256 131 65.8 43.1 32.8 21.6 16.0 10.6 6.89 5.04 Safety timer (min.) 10 20 40 60 80 120 160 250 380 520 Safety Timer vs. RTMR
Selecting Mode of Operation The SS6781A provides three modes of operation: normal, test, and AC mode determined by the setting of MODE pin according to TABLE 9. The SS6781A will operate normally when the MODE pin is left floating (a 0.1F capacitor is recommended 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 SS6781A enters the test mode. The test mode can be used to significantly reduce production test time. For relevant information, please contact SSC directly.
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TABLE 9 MODE pin VCC Floating GND The Operating Mode of SS6781A Mode Test Function Safety timer period scaled down to 1/32....etc. -V detection disabled TYPE 2
Power ON LED1 LED2 1Hz 1Hz Charge Fault Fast Charging Completed Conditions ON 4Hz Flashing OFF ON 4Hz Flashing OFF
Normal Normal operation AC
The Mode of LED Display and Trickle Charge The SS6781A 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 10 Mode of LED Display and Trickle Charge SEL1 SEL2 VCC VCC Floating GND VCC Floating Floating GND VCC GND 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
Charging Current Control As shown in the typical application circuit, the SS6781A 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 SS6781A 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.
Fast Charge Fault Power ON Charging Completed Conditions ICON ON OFF See pin 10 & 11 ON
Display the Battery Charging Status The SS6781A provides two open-drain
Test Mode Fig. 20 shows the timing diagram for externally controlled PEAK, ADJ, VBT, VTS, SEL1 and SEL2 pin voltages of a recommended SS6781A test scheme, utilizing TEST mode function. Output waveforms of LED1, LED2 and ICON of a properly functioning SS6781A are also shown in the figure.
outputs, LED1 and LED2, to indicate the battery charging status. Refer to the table of LED display mode (TABLE 10), depending on the setting of SEL1 and SEL2 pins, the outputs of LED1 and LED2 pins are shown in the following table: TYPE 1
Fast Charge Fault Power ON Charging Completed Conditions LED1 LED2 1Hz OFF ON OFF OFF ON OFF OFF
1/11/2005 Rev.2.10
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SS6781A(G)
TIMING DIAGRAM
VCC, SEL3, MODE=5V, (DSW FREQ.=820kHz, 25 TIMES of 32.8k)
Power Init. ON PEAK TIMER TEST
-V TEST 0V
T/t INITIAL TIMER
T/t TEST
SAFETY TIMER TEST
PEAK
5V
5V ADJ 3V
1.12V
<2.1V (-0.15%) 2V 1.95V 1.997V 2V (-0.15%) 1.997V 1.9V 1.993V (-0.35%) 4V 2V 1.97V (-2.15%) 1.85V (-2.5%) 2V 2mV Step/100mS
VBT 1.5V 2V VTS 0V 4V
4V 2V 2mV Step/100mS
4V 2V
OFF ON LED1 OFF LED2 OFF
ON
OFF ON 3.2KHz
ON
OFF ON
OFF
ON OFF ON OFF
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 0.7
0.5 7
GND Floating
0.24 0.4 8
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. 20
Timing Diagram of SS6781A in Test Mode
1/11/2005 Rev.2.10
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SS6781A(G)
PHYSICAL DIMENSIONS (unit: mm)
16 LEAD PLASTIC SO (300 mil) (CS/GS)
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 H
e A
1.27(TYP)
A1
B
c
L
L
16 LEAD PLASTIC DIP (CN)
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
A2 A1 L eB b e C
E1 e eB L
2.54(TYP)
Information furnished by Silicon Standard Corporation is believed to be accurate and reliable. However, Silicon Standard Corporation makes no guarantee or warranty, express or implied, as to the reliability, accuracy, timeliness or completeness of such information and assumes no responsibility for its use, or for infringement of any patent or other intellectual property rights of third parties that may result from its use. Silicon Standard reserves the right to make changes as it deems necessary to any products described herein for any reason, including without limitation enhancement in reliability, functionality or design. No license is granted, whether expressly or by implication, in relation to the use of any products described herein or to the use of any information provided herein, under any patent or other intellectual property rights of Silicon Standard Corporation or any third parties.
1/11/2005 Rev.2.10
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