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SC802/SC802A
Fully Integrated Lithium-Ion Battery Charger System with Timer
POWER MANAGEMENT Features
Integrated charger with pass FET, reverse-blocking diode, sense resistor, timer, and thermal protection Battery Voltage -- 4.1V, 4.2V, and adjustable Programmable pre-charge, fast-charge, & termination current Battery voltage controlled to 1% accuracy Soft-start for glitch-free adaptor plug-in Continuous charge current -- Up to 1.5A Charge current monitor output for microcontroller or ADC interface Input voltage range -- 4.3V to 14V Battery Drain when not charging -- 0.1A Operates without a battery in regulated LDO mode Small 4 x 4(mm) 16 lead MLPQ package NTC thermistor sense input Adjustable up to 6 Hour programmable charge timer Over-current protection in all charging states Over-voltage protection Remote Kelvin sensing at the battery terminals ADC input current control capable Status output for charging and end of charge cycle Charges Li-Ion, Li-Polymer, NiCd, and NiMH Batteries
Description
The SC802 and SC802A are fully integrated, single cell, constant-current/constant-voltage Lithium-Ion/Lithium Polymer battery chargers. With an integrated timer and complete charge control algorithm, the devices are optimized for stand-alone charger applications. They provide for programmable pre-charge, fast-charge, and termination current settings. The devices can be programmed to terminate the charge cycle based on the output current or the time-out of the programmable timer. The fast-charge current is typically set with an external resistor but can be modified with the analog fast-charge input to allow a Power Management Controller to control the fast-charge current setting via DAC. The 14V input voltage range of the SC802 and SC802A eliminates additional protection circuitry required by other 5V chargers in the event of faulty adapters. Reference ground and battery sense inputs are provided to allow Kelvin connections, to eliminate errors due to IxR voltage drops during charging. The output voltage to the battery is controlled to within 1% of the programmed voltage for either 4.1V or 4.2V. The SC802 and SC802A can also function as a general purpose current sources, such as for charging nickel-cadmium (NiCd) and nickel-metal-hydride (NiMH) batteries. The SC802A version of the device is optimized for high termination current applications.
Applications
Cellular phones and PDA's Handheld meters Charging stations Handheld computers Digital cameras Programmable current source
Typical Application Circuit
CHARGER VIN SC802/SC802A CPB VCC1 CHRGB VCC2 RTIME IPRGM EN_NTC VPRGM BSEN ITERM VOUT1 BIPB VOUT2 GND AFC RFGND RITERM AFC ISET CHARGER PRESENT
RNPU
CHARGE
RIPRGM CVCC 1F RNTC Battery Thermistor
BAT.
CVOUT 2.2F
RRTIME
October 30, 2008
(c) 2008 Semtech Corporation
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SC802/SC802A
Pin Configuration
VOUT2 VOUT1 VCC2 VCC1
Ordering Information
Device
SC802IMLTRT(1)(2) SC802AIMLTRT(1)(2) SC802EVB
(3)
Package
MLP16 MLP16 Evaluation Board Evaluation Board
16 BSEN VPRGM IPRGM ITERM 1
15
14
13 12 RTIME CPB CHRGB AFC
TOP VIEW 2 3 4 T 11 10 9
SC802AEVB(3)
Notes: (1) Available in tape and reel only. A reel contains 3,000 devices. (2) Available in lead-free package only. Device is WEEE and RoHS compliant. (3) Specify the part number when ordering.
5
REFGND
6
GND
7
EN_NTC
8
BIPB
MLP-16, 4x4, 16 LEAD JA = 50C/W
Marking Information
802 yyww
yyww = datecode
802A yyww
yyww = datecode
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SC802/SC802A
Absolute Maximum Ratings
VCC1, VCC2, EN_NTC (V) . . . . . . . . . . . . . . . . . . . -0.3 to +14.0 VOUT1, VOUT2, RTIME(V) . . . . . . . . . . . . . . . . . -0.3 to +6.0 BIPB, CPB, CHRGB (V) . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0 IPRGM, ITERM, AFC (V) . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0 VPRGM, BSEN (V) . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0 REFGND to GND (V) . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +0.3 VOUT Short to GND (1) . . . . . . . . . . . . . . . . . . . . . . Continuous ESD Protection Level (2) (kV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Recommended Operating Conditions
Ambient Temperature Range (C) . . . . . . . . -40 < TA < +85 VCC Operating Voltage (1)(3) (V) . . . . . . . . 4.3 < VVCC1,2 < 6.5
Thermal Information
Thermal Resistance, Junction to Ambient (4) (C/W) . . . . 50 Maximum Junction Temperature (C) . . . . . . . . . . . . . . +150 Storage Temperature Range (C) . . . . . . . . . . . . -65 to +150 Peak IR Reflow Temperature (10s to 40s) (C) . . . . . . . +260
Exceeding the above specifications may result in permanent damage to the device or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not recommended. NOTES: (1) VCC1 and VCC2, and VOUT1 and VOUT2, must be connected, and will be referred to collectively as VCC and VOUT, respectively. All references to VVCC, VVOUT, IVCC, and IVOUT refer to the common node voltage and total current of VCC1 and VCC2, and VOUT1 and VOUT2, respectively. (2) Tested according to JEDEC standard JESD22-A114-B. (3) Operating voltage is the input voltage at which the charger is guaranteed to begin operation. Maximum operating voltage is the maximum Vsupply as defined in EIA/JEDEC Standard Number 78, paragraph 2.11. (4) Calculated from package in still air, mounted to 3 x 4.5(in), 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards.
Electrical Characteristics
Test Conditions: VVCC = 5.00V (1), VVOUT = 3.70V unless specified. Typ values at 25C. Min and Max at -40C < TA < 85C, unless specified.
Parameter
VCC UVLO Rising Threshold VCC UVLO Hysteresis VCC OVP Rising Threshold VCC OVP Falling Threshold VCC OVP Hysteresis
Symbol
VTUVLOR VTUVLOH VTOVPR VTOVPF VTOVPH ICCDIS
Conditions
Min
3.7
Typ
4.0 40
Max
4.3
Units
V mV
6.5 6.1 VTOVPR - VTOVPF VEN_NTC = 0V, CHRGB, CPB off VEN_NTC = 0.5 x VVCC, CHRGB, CPB off LDO Mode, CHRGB, CPB off VVCC = 0V, VVOUT = VBSEN = 4.5V VVPRGM = VVCC VVPRGM = 0V VVOUT_RGND = VVOUT - VCVn, VREFGND = 30mV VREFGND = 0V 4.16 4.06 22 1 8 200
6.8 6.5 300 2.6 2.4 16 0.1 4.20 4.10 30 35
7.5 7.1 500
V V mV
Operating Current
ICCCHG ICCLDO
3.5 23 2 4.24
mA
Battery Leakage Current (sum of IVOUT and IBSEN) Regulated Voltage
ILeakBAT VCV-HI VCV_LO
A
V 4.14 38 mV A
REFGND Output Accuracy REFGND Current
VVOUT_RGND IREFGND
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SC802/SC802A
Electrical Characteristics (continued)
Parameter
Adjust Mode Feedback Voltage Adjust Mode VPRGM Shunt Resistance Adjust Mode Threshold Voltage SC802 Pre-Charge Current SC802 Termination Current SC802 Fast-Charge Current SC802 AFC Fast-Charge Current SC802A Pre-Charge Current SC802A Termination Current SC802A Fast-Charge Current SC802A AFC Fast-Charge Current IPROG Regulated Voltage VVOUT Pre-charge Threshold (2) VVOUT Re-charge Threshold (3) Over Temperature Shutdown
Symbol
VADJMF RVPGMSH
Conditions
VPRGM = External Divider, 4.2V VCC 6.5V Adjust Mode, VVPRGM = 0.1V VVOUT - VBSEN RITERM = 3.01k RITERM = 3.01k RIPRGM = 3.01k, VVOUT = 3.8V RIPRGM = 3.01k, VAFC = 0.75V RITERM = 976 RITERM = 976 RIPRGM = 1.78k, RITERM = 976, VVOUT = 3.8V RIPRGM = 1.78k, RITERM = 976, VAFC = 0.75V, VVOUT = 3.8V
Min
Typ
3.0
Max
Units
V
0.5 50 74 35.5 450 200 135 135 740 310 1.4
1 250 82 42 500 240 145 145 800 367 4.5 2.8 100 150
5 420 90 49.5 550 280 160 160 860 430 1.6 2.9 140
k mV mA mA mA mA mA mA mA mA V V mV C
VTADJM IPREQ ITERMQ IFastQ IFQ_ADJ IPREQA ITERMQA IFastQA IFQ_ADJA VIPRGM VTPreQ VTReQ TOT-R VTNTC_DIS
RTNTC_HF
measured at VOUT pins VCV (at BSEN) - VBSEN-FDBK Hysteresis = 10C Disable (Falling) NTC Hot (Falling), tested at VVCC = 5V NTC Cold (Rising), tested at VVCC = 5V Charger Enable, tested at VVCC = 5V Hot/Cold threshold hysteresis, tested at VVCC = 5V VRTIME < VT TIMER Disables Timer VCC-VRTIME < VTINTTS selects internal timer RTIME tied through 36.5k to GND RTIME tied through 36.5k to GND
2.7 70
0.5 28 72 84
<1 30 75 90 50
1.1 32 78 92
V % % % mV
EN_NTC Thresholds
RTNTC_CR RTNTC_EN VTNTC_HYS
Timer Disable Threshold Internal Timer Select External RTIME Voltage
VT TIMER VTINTTS VRTIME
0.7
1 1.5
1.1
V V
1.4 50
1.5
1.6
V
Pre-Charge Fault Time-out
TPreQF RTIME tied to VCC RTIME tied through 36.5k to GND -35% 45 3.3 +35
min
Charge Complete Time-out
TQCOMP RTIME tied to VCC -35% 3 +35
hr
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SC802/SC802A
Electrical Characteristics (continued)
Parameter
CHRGB Charge LED On CHRGB Charge LED OFF CPB LED On CPB LED Off
Symbol
VCHRGB ICHRGB VCPB ICPB VIH
Conditions
Load = 5mA Leakage Current, V = 5V Load = 5mA Leakage Current, V = 5V
Min
Typ
0.5
Max
1 1
Units
V A V A
0.5
1 1
1.8 V 0.4
BIPB, VPRGM Inputs VIL
Notes: (1) Electrical Characteristics apply for VVIN = 4.75V to 5.25V, but are tested only at VVIN = 5.00V, unless noted. (2) Pre-charge threshold is applied directly at VOUT for any setting of VCV, whether 4.1V or 4.2V fixed, or Adjust Mode. (3) Re-charge threshold is relative to VCV as measured at BSEN. For either of the fixed output voltage settings, VBSEN is compared directly to the programmed CV regulation voltage. In Adjust Mode, VBSEN is compared to the Adjust Mode feedback voltage, VADJMF. So the re-charge threshold at the battery is VTReQ x VCV / VBSEN-FDBK.
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SC802/SC802A
Typical Characteristics
Output Current (SC802) versus RIPRGM
2
250
Output Current (SC802) versus RITERM
200
1.5
Current (mA)
150 IPQ 100
Current (A)
1 IFQ
0.5
50 ITERM
0 0.75
1
1.5
2
2.5
3
3.5 4 RIPRGM (k )
4.5
5
5.5
6.5
7
0 0.8
1.5
2.5
3.5
6 4.5 RITERM (k )
8.5
10
11.85
14
Drop-out Voltage versus Output Current
700 600
8
Time-out versus Output RRTIME
Dropout Voltage (mV)
500 400 300 200 100 0 54 100 200 250 450 500 300 Output Current (mA) 600 800 1000
Time-out (hrs)
6 TQCOMP 4
2 TPreQ
0 10
20
40 RRTIME (k )
60
80
Battery Charge Profile
0.6 4.4 4.2 4 VVOUT 3.8 3.6 IVOUT 3.4 3.2 3 0 25 50 75 100 t (minutes) 125 150 175 200 225 VCHRGB 0.1 0 0.2 0.3 0.5
0.4
CURRENT (A)
VOLTAGE (V)
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SC802/SC802A
Pin Descriptions
Pin # Pin Name Pin Function
Battery voltage sense pin -- Connect to battery terminal to Kelvin sense battery voltage, to a resistor divider network for adjustable output voltage, or to VOUT otherwise. Do not leave this pin floating. Selectable voltage program pin -- Logic low = 4.1V; Logic high = 4.2V; Resistor = adjustable. Charger current program pin in fast-charge mode -- Requires a resistor to ground to program fast-charge current. Selection for current termination and pre-charge current -- Requires a resistor to ground to program pre-charge and termination current. Reference ground -- Allows Kelvin connection to battery negative terminal. Ground Combined device enable/disable and NTC input pin -- Logic high enables device; logic low disables device. Analog voltages between 0.3xVVCC and 0.75xVVCC enable the NTC function. Battery In Place Bar (BIPB) -- selects Charge/LDO mode. BIPB = Low selects charge mode. BIPB = High selects LDO mode which disables Pre-Charge and timer functions Analog fast-charge setting -- Connect to DAC for analog control of fast-charge current value. Connect to VCC to disable AFC. Do not leave open. Open drain charger status pin -- The output is active low when the charger is on and IVOUT > ITERM. The CHRGB output switches to high impedance when IVOUT < ITERM. This pin can sink 10mA. Open Drain Charger present indicator -- The output is active low when the VVCC exceeds VTUVLOR. This pin can sink 10mA. Programmable timer input pin -- Connect to VCC to select the internal time-out of 3hrs. Connect an external resistor to ground to program the timeout period. Connect to ground to disable the timer. Supply pin -- Connect to adaptor power and to VCC2. (1) Supply pin -- Connect to adaptor power and to VCC1. (1) Charger output -- Connect to battery and to VOUT2. (2) Charger output -- Connect to battery and to VOUT1. (2) Pad is for heatsinking purposes -- The thermal pad is not connected internally. Connect exposed pad to ground plane using multiple vias.
1
BSEN
2 3 4 5 6 7 8 9 10 11
VPRGM IPRGM ITERM REFGND GND EN_NTC BIPB AFC CHRGB CPB
12
RTIME
13 14 15 16 T
VCC1 VCC2 VOUT1 VOUT2 Thermal Pad
Notes: (1) VCC1 and VCC2 must be connected. VCC1 and VCC2 will be referred to collectively as VCC. All references to VVCC and IVCC refer to the common node voltage and total current of VCC1 and VCC2. (2) VOUT1 and VOUT2 must be connected. VOUT1 and VOUT2 will be referred to collectively as VOUT. All references to VVOUT and IVOUT refer to the common node voltage and total current of VOUT1 and VOUT2.
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SC802/SC802A
Block Diagram
BSEN
1
VCC
13 14
AFC
9
4.1V Reference 4.2V Voltages Fast Charge Ref Pre-Charge Ref
Pre-charge Ref
REFGND
5
Vout Vout VPRGM 16
VPROG Mode Detect
Pre-Charge On Fast Charge On Control Charge/LDO On
15 16
VOUT VOUT
GND BIPB
6 8
Over Temp Under Voltage Over Voltage
EN-NTC
7
NTC Interface
Programmable Timer Fast Charge Ref
3 4
IPRGM ITERM
RTIM 12 CPB 11 CHRGB 10
ITERM
GND
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SC802/SC802A
Applications Information
General Operation
The SC802 and SC802A can be configured independently with respect to fast-charge and termination current, output voltage, timing, and operation with and without a battery (LDO mode). A typical charging cycle is described in this section. Details on alternate applications and output programmability are covered in subsequent sections. Wherever the SC802 and SC802A descriptions are the same, the part will be referred to as the SC802/A. The charging cycle begins when the adapter is plugged in. The SC802/A performs glitch filtering on the VCC input and initiates a charge cycle when VVCC > VTUVLOR. The CPB and CHRGB signals turn on the charger LED's. If the battery voltage is less than 2.8V, the SC802/A will charge the output with the pre-charge current. When the battery voltage exceeds 2.8V, the SC802/A enters fast-charge or Constant Current (CC) regulation. When the battery voltage reaches its final value, the charger enters Constant Voltage (CV) regulation. The CV regulation output voltage, (VCV ), can be programmed to fixed values VCV-HI = 4.2V, VCV-LO = 4.1V, or programmed to any voltage VCV-ADJ using the available Adjust Mode. In CV regulation the battery accepts decreasing current until the output current (IVOUT ) reaches the programmed termination current, designated (ITERM). When IVOUT < ITERM, an event known as charge termination, the CHRGB status indicator turns off, but the SC802/A continues to hold the battery in CV regulation until the timer cycle is completed. At this point the charger enters the monitor state where the output remains off until VVOUT drops by VTReQ, nominally 100mV, and a new charge cycle is initiated. current is programmed according to the following equations.
ITERM ITERM 1.5 88 RITERM 1.5 97 RITERM
(SC802) (SC802A)
The termination current is programmable up to 67mA for the SC802, and up to 150mA for the SC802A.
Pre-Charge
Pre-charge regulation is automatically enabled when the battery voltage is below the pre-charge threshold, VTPreQ, nominally 2.8V. Pre-charge is required to precondition the battery for fast-charging, and to limit the power dissipation in the charger. The pre-charge current value, IPQ, is determined by the ITERM pin resistance to ground. The pre-charge current is programmable from 10mA to 125mA with the SC802, and up to 150mA with the SC802A. The pre-charge current is given by the following equations.
IPQ IPQ 2.8 88 RITERM 1.5 97 RITERM
(SC802) (SC802A)
Termination Current
When the battery reaches the CV voltage (VCV), the charger transitions from a constant current source to a constant voltage source. The current through the battery begins to decrease while the voltage remains constant until the current decreases below the programmed termination current set by the ITERM pin resistance to ground. Upon termination, the SC802/A will turn off the CHRGB status indicator. If the timer is enabled, the output will remain in CV regulation until the timer cycle is complete. If the timer is disabled, then the output will turn off as soon as the termination current level is reached. The termination
If the charge timer is enabled, a pre-charge timer is also enabled. If the pre-charge time exceeds 1/4 of the programmed total charge time, the charger will turn off and a pre-charge fault will be indicated by blinking the CHRGB status indicator. This fault is cleared when the charger is disabled (by grounding the EN_NTC pin), or the VCC input voltage is cycled, or the output voltage rises above 2.8V.
Fast-Charge
Fast-charge or CC regulation is active when the battery voltage is above VTPreQ and less than VCV, the final float charge voltage of the battery. The fast-charge current can be set to a maximum of 1.5A and is selected by the program resistor on the IPRGM pin. The voltage on this pin represents the current through the battery. It enables a microprocessor via an Analog-to-Digital Converter (ADC) to monitor battery current by sensing the voltage
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SC802/SC802A
Applications Information (continued)
on the IPRGM pin. The fast-charge current is given by the following equations.
IFQ IFQ 1.5 1000 RIPRGM 1.5 1000 0.3 ITERM RIPRGM
Output State
On
BIPB
High Low Low Low
Timer
N/A t < TQCOMP t > TQCOMP Disabled
IVOUT
N/A N/A N/A < ITERM
(SC802)
On
(SC802A)
Off Off
Note that for a given program resistor the current through the battery in CV regulation can be determined by replacing 1.5 with the actual voltage on the IPRGM pin in the equations. In the case of the SC802A, the ITERM term applies only prior to termination (while CHRGB is low), and should be excluded following termination. The CC current can also be modified by applying an analog voltage to the AFC pin as described in the next section.
Charge Timer
The timer in the SC802/A provides protection in the event of a faulty battery, and maximizes charging capacity. Connect the RTIME pin to VCC to select the internally programmed timer, and to GND to disable the timer. Connecting a resistor between the RTIME pin and GND will program the total charge complete time TQCOMP according to the following equation. RRTIME (k) = TQCOMP (hours) x 12.5 (k/hour) The timer is programmable over the range of two to six hours. The internal timer selection provides a charge time of three hours. The SC802/A automatically turns off the output when the charge timer times out, and then enters the Monitor State. A re-charge cycle resets and restarts the timer. Note that the CHRGB fault indication blink rate is a function of the timer setting, whether externally programmed or set internally. When the timer is disabled, the blink rate is the same as if the timer were internally set.
Analog Fast-Charge
Many applications require more than one current setting for fast-charge. This feature is included in the SC802/A by using the AFC function. When the AFC pin is connected to VCC the SC802/A operates as described in the previous section. When the AFC pin is driven by an analog voltage between 0 and 1.5V the SC802/A automatically uses this pin voltage to set the maximum fast-charge current setting according to the following equation.
IAFQ IAFQ VAFC 1000 RIPRGM VAFC 1000 0.3 ITERM RIPRGM
(SC802) (SC802A)
Monitor State
When a charge cycle is completed, the SC802/A output turns off and the device enters monitor state. If the voltage of the battery falls below the re-charge voltage of VCV - VTReQ, nominally 100mV below VCV, the charger will clear the charge timer and re-initiate a charge cycle. The maximum current drain from the battery during monitor state is less than 1A over temperature. The status of the charger output as a function of BIPB, timer status, and IVOUT in the following table.
EN_NTC Interface
The EN_NTC pin is the interface to a battery pack temperature sensing Negative Temperature Coefficient (NTC) thermistor. It can be used to suspend charging if the battery pack temperature is outside of a safe-to-charge range. The EN_NTC interface also serves as a charger disable or NTC-unconditional enable input. The recommended EN_NTC network is a fixed-value pullup resistor (designated RNPU) from the EN_NTC pin to the VCC pins, and the battery pack NTC thermistor (designated RNTC) from the EN_NTC pin to ground. In this configuration, shown in the Typical Application Circuit on
(c) 2008 Semtech Corporation
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SC802/SC802A
Applications Information (continued)
page 1, an increasing battery temperature produces a decreasing NTC pin voltage, designated VEN_NTC. When VEN_NTC is greater than the high (cold) threshold (but below the Charger Enable threshold) or less than the low (hot) threshold (but above the Disable threshold), the charge cycle is suspended, turning off the output. This suspends but does not reset the charge timer, and indicates a charging fault by blinking the CHRGB status indicator. Hysteresis is provided for both high and low NTC thresholds to avoid chatter at the NTC temperature fault thresholds. When VEN_NTC returns to the Temperature-OKto-Charge range, the charge timer resumes, CHRGB is asserted (pulled low), the charging output is enabled, and the charge cycle continues. The timer will expire when the output on-time exceeds the timer setting, regardless of how long it has been disabled due to an NTC fault. All EN_NTC input thresholds are proportional to the VCC pin voltage (VVCC). When the recommended external NTC circuit is used, the external EN_NTC pin voltage is also proportional to V VCC, varying with the thermistor resistance. This ensures that all EN_NTC thresholds are insensitive to VVCC. The ratiometric hot and cold thresholds are given by the parameters RT NTC_HF and RT NTC_CR. V EN_NTC between RT NTC_HFxV VCC and RT NTC_CRxV VCC indicates the battery temperature is safe to charge, and enables charging. See the following table. EN_NTC Pin Ratiometric Thresholds and CHRGB is turned off (high). The behavior of CPB differs between the SC802 and SC802A when the device is disabled. See the Status Indicators section. Charger Enable is selected when the battery (along with the thermistor) is removed, determined by the NTC pin exceeding RTNTC_EN x VVCC, nominally 90% of the VCC pin voltage. Charger Enable behaves identically to NTC safeto-charge. Charger Enable also provides a convenient means to operate the SC802/A in applications without a battery thermistor, without requiring a passive resistor network to obtain 50% of VVCC. Connect EN_NTC directly to VCC, or via a pullup resistor if it will be necessary to disable the charger by pulling EN_NTC to ground. The response of the SC802/A to an EN_NTC pin voltage above the NTC Cold Fault threshold (but below RTNTC_EN) or below the low NTC Hot Fault threshold (but above VTNTC_DIS) is the same. Therefore the EN_NTC network can be configured with the battery pack thermistor between EN_NTC and VCC, and a fixed resistor between EN_NTC and ground, reversing the designation of the hot and cold thresholds. This configuration may be used to disable the charger when the battery pack is removed. For detailed design guidance for ratiometric NTC interfaces, including thermistor selection guidelines, see the Semtech Application Note AN-PM-0801, NTC Thermistor Network Design for Ratiometric Thresholds.
Status Indicators
% of VVCC
RTNTC_EN = 90% RTNTC_CR = 75% RTNTC_HF = 30% NTC Hot Fault RTNTC_DIS = 1V Charger Disable
Range
Charger Enable NTC Cold Fault
VEN_NTC Ratiometric Thresholds
There are two status indicator outputs on the SC802/A -- CHRGB (Charge) and CPB (Charger Present). These outputs are open drain n-channel MOSFET drivers suitable for driving LEDs directly. The following table defines each output state.
NTC TemperatureOK-to-Charge
When VEN_NTC < 1V approximately, the SC802/A charger is disabled. This allows the system controller to asynchronously disable or reset the device by pulling EN_NTC to ground, using for example an n-channel FET. When disabled, the charger is turned off, the charge timer is reset,
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SC802/SC802A
Applications Information (continued)
Status Indicator ON (active low)
UVLO < VVCC< OVP
OFF (inactive high)
Power Not Good
Blinking
charge timeout. The status indicator states for these fault conditions are shown in the following table.
Fault CPB
OFF ON ON OFF
CHRB
OFF Blinking Blinking OFF
CPB
X
VCC UVLO or VCC OVP
Pre-charge or NTC fault
CHRGB
IOUT > ITERM
IOUT < ITERM(1)
NTC Fault Pre-Charge Time-out
(1) Output remains on when timer is enabled and t < TQCOMP.
TJ > 150C
The CPB output can be used as a VCC-valid detector. When V VCC is between the UVLO and OVP thresholds the CPB output is low. In the SC802, the CPB output reflects the voltage of the VCC input regardless of the voltage VEN_NTC. In the SC802A, the CPB output becomes inactive (high) when the charger is disabled, regardless of VVCC. The CHRGB output signifies the charging status. When IVOUT > ITERM, CHRGB is driven low. CHRGB is high when IVOUT < ITERM. The CHRGB output is latched during the charge cycle when the output current is less than ITERM. This latch is reset when the battery enters a re-charge cycle, or if BIPB, EN_NTC, or VCC are toggled. The CHRGB indicator operates the same way in both charging and LDO modes. The five fault conditions detected by the SC802/A are input under-voltage, input over-voltage, NTC temperature fault, maximum die over-temperature (OT) fault, and pre-
Configuring the Output Voltage to the Battery
VCV Fixed Mode The battery voltage is set by the VPRGM pin in fixed mode and externally in the adjust mode. If VPRGM is logic high the output voltage is set to 4.2V. If this pin is logic low the output voltage will be set to 4.1V. For a value other than 4.1V or 4.2V a resistor divider is required. VCV Adjust Mode VCV Adjust Mode permits configuring the SC802/A for VCV other than 4.1V or 4.2V. In VCV Adjust Mode the CV regulation voltage is set by an external resistor divider. The SC802/A Adjust Mode schematic is shown in Figure 1. The SC802/A provides the capability, via the VPRGM pin, to disconnect the external feedback resistor divider when the charging source is removed, to reduce current drain from the battery through the resistor network. Connect the external resistor divider between the VOUT pins and
CHARGER VIN
SC802/SC802A CPB VCC1 CHRGB VCC2 RTIME IPRGM EN_NTC VPRGM BSEN ITERM VOUT1 BIPB VOUT2 GND AFC RFGND RITERM AFC ISET CVOUT 2.2F CHARGER PRESENT
RNPU
CHARGE RADJ-LO RADJ-HI CADJ
RIPRGM CVCC 1F
RNTC Thermistor
BAT.
RRTIME
Figure 1. VCV Adjust Mode programming.
(c) 2008 Semtech Corporation 12
SC802/SC802A
Applications Information (continued)
the VPRGM pin with the divider tap connected to the BSEN pin to utilize this feature. The Adjust Mode CV regulation voltage is set by the following equation.
R ADJ HI R ADJ LO
VCV
ADJ
1
3.0
To ensure detection of VCV Adjust Mode, RADJ-HI should be at least 130k. The capacitor across RADJ-HI in the feedback network provides zero-pole frequency compensation for stability. Place the zero according to the following equation to ensure stability.
R ADJ HI C ADJ 2 1 100kHz
positive terminal as possible. The REFGND pin should be Kelvin connected to the negative terminal of the battery. This provides maximum flexibility in PCB layout. This also results in a greater accuracy in sensing the battery voltage at the battery terminals. When laying out the PCB the designer should route the BSEN pin directly to the battery terminal connections. (For Adjust Mode, the high-side resistor should be connected directly to the battery terminal connections.) In LDO mode, as in Charging mode, the BSEN pin must sense the output voltage, so BSEN should never be left unconnected.
Over-Current and Max Temperature Protection
Over-current protection is inherent in all modes of operation. When the device is in charge-mode (BIPB=low) the output is current limited to either the pre-charge current limit value or the fast-charge current limit value depending on V VOUT. When the device is in LDO mode (BIPB = high) the output current is limited to the fast-charge current limit. Maximum die temperature protection is provided on the SC802/A. This feature allows the SC802/A to operate with maximum power dissipation by disabling the output current when the die temperature reaches the over temperature limit. The device will then operate as a pulse charger in extreme power dissipation applications, delivering the maximum allowable output current while regulating the internal die temperature to a safe level.
In VCV Adjust Mode, VCV-ADJ must satisfy V VCC > VCV-ADJ + 150mV to ensure regulation. If V VCC approaches VCV-ADJ, VCV-ADJ will drop out such that VCV-ADJ will be approximately VVCC - 150mV.
LDO Mode
The SC802/A can operate with or without a battery. If the battery is not in place the device can enter LDO Mode. The input pin BIPB is used to switch the SC802/A from charger mode to LDO mode. If this pin is driven logic high the device will be in LDO mode, if it is logic low it will be in the charger mode. The BIPB pin should never be left floating. It should be tied through pull-up or pull-down resistors when connected to a high impedance control pin or it can be connected directly to the VCC pin or GND. In LDO Mode the SC802/A will function as a low dropout voltage regulator. The EN_NTC pin functions remain active, and the status indicators are active, including the CHRGB indicator. The timer is inactive. The output remains enabled even when IVOUT < ITERM. The output voltage can be set to 4.1V, 4.2V or externally set by a resistor divider, with a current limit equal to IFQ. The pre-charge threshold is ignored.
Capacitor Selection
Low cost, low ESR ceramic capacitors such as the X5R and X7R dielectric material types are recommended. The VOUT pin capacitance range is typically 1F to 4.7F, but C VOUT can be as large as desired to accommodate the required input capacitors of regulators connected directly to the battery terminal. The VCC pin input capacitor CVCC is typically between 0.1F to 1F, but larger values will not degrade performance. Capacitance must be evaluated at the expected bias voltage (VCV for CVOUT, the expected VCC supply regulation voltage for CVCC), rather than the zerovolt capacitance rating.
Remote Kelvin Sensing at the Battery
Kelvin sensing of both the positive and negative terminals of the battery is available on the SC802/A. The BSEN pin provides the positive sensing voltage feedback to the CV amplifier and should be connected as close to the battery
(c) 2008 Semtech Corporation 13
SC802/SC802A
State Diagram
VTUVLO < VVCC < VTOVP Over Voltage or Under Voltage will disable (and reset) the SC802/A, regardless of charger state. Over Temperature will turn off output but preserve charger state.
Charger Enabled? Yes Soft Start CHRGB Low
Shutdown Mode VOUT off CHRGB High Z CPB Low
CC = Constant Current CV = Constant Voltage
Start LDO Mode
BIPB = Low?
Yes
Timer Enabled? Yes
IVOUT < ITERM ? Yes CHRGB High Z
Soft Start CC Mode
Start Timer
IVOUT = IFQ Yes
Start Pre-Charge
Float Charge Mode VVOUT = VCV Yes
VVOUT = VCV ? Yes
VVOUT > VTPreQ ?
VVOUT < VCV - VTReQ ? Yes
Start CV Regulation t > TQCOMP ?
IVOUT = IFQ
t > TPreQF = TQCOMP / 4 ? Yes
IVOUT < ITERM ? Monitor Mode VOUT is off Yes CHRGB High Z
Pre-Charge Timeout Fault CHRGB blinks at 0.5Hz Cleared by VVOUT > 2.8V or Re-cycle EN or VCC
Yes
VVOUT < VCV - VTReQ ?
Timer Enabled? Yes Yes t > TQCOMP ?
VEN_NTC < RTNTC_HF x VVCC or VEN_NTC > RTNTC_CR x VVCC
Float Charge Mode VVOUT = VCV
NTC Temperature Fault CHRGB blinks at 0.5Hz Timer is frozen Charge resumes when NTC Temperature is valid
(c) 2008 Semtech Corporation
14
SC802/SC802A
Charge Mode Timing Diagram
UVLO VCC 2.8V VOUT IOUT Fast Charge Soft Start Pre-Charge CC-mode CPB On Termination Re-Charge Threshold Current
CV- mode
CHRGB
On
Off
TIMER
On
Off
On
Hold
On
NTC
Fault
LDO Mode Timing Diagram
UVLO VCC 2.8V VOUT Fast Charge IOUT Soft Start CC-mode CPB CV-mode Load Current Transient On Termination Current Re-Charge Threshold
CHRGB TIMER (Disabled)
On
Off
Off
NTC
Fault
(c) 2008 Semtech Corporation
15
SC802/SC802A
Evaluation Board Schematic
TP2 TP2 Charger- Charger+ 1 1 TP3 EN-NTC 1 TP4 VOUT 1 TP5 GND 1
C1 1F 2 JP3 LDO 1
TP7 ISENSE 1 R1 10k
D2 CP D3 No Pop SC802/SC802A VCC1 CPB 11 VCC2 CHRGB 10 12 IPRGM RTIM EN_NTC VPRGM 2 ITERM BSEN 1 8 BIPB VOUT1 15 6 GND VOUT2 16 5 RFGND AFC 9 D1 CHRG
2 JP2 TINT 1 R2 100k
1 JP1 4.2V 2
TP6 AFC 1
13 14 3 7 4
R6 1M
TP8 RGND 1
R3 3k R4 3.01k
1 JP4 4.1V R7 37.5k 2
R5 0
C2 No Pop
C3 2.2F
R9 0
R8 No Pop
(c) 2008 Semtech Corporation
16
SC802/SC802A
Outline Drawing -- MLPQ-16 (4x4x0.9mm)
DIMENSIONS B DIM A A1 A2 b D D1 E E1 e A2 A aaa C A1 D1 e/2 LxN E/2 E1 2 1 N e bxN D/2 NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS. bbb C A B C SEATING PLANE L N aaa bbb INCHES MIN .031 .000 .010 .154 .079 .154 .079 NOM (.008) MAX .039 .002 .014 .161 .089 .161 .089 .026 MILLIMETERS MIN 0.80 0.00 0.25 3.90 2.00 3.90 2.00 NOM (0.20) MAX 1.00 0.05 0.35 4.10 2.25 4.10 2.25 0.65
A
D
PIN 1 INDICATOR (LASER MARK)
E
.012 .157 .085 .157 .085 .026 BSC .018 .022 16 .003 .004
0.30 4.00 2.15 4.00 2.15 0.65 BSC 0.45 0.55 16 0.08 0.10
(c) 2008 Semtech Corporation
17
SC802/SC802A
Outline Drawing -- MLPQ-16 (4x4x0.9mm)
K DIMENSIONS DIM C (C) H G Z G H K P Y X Y X P NOTES: 1. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 2. THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD SHALL BE CONNECTED TO A SYSTEM GROUND PLANE. FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR FUNCTIONAL PERFORMANCE OF THE DEVICE. 3. SQUARE PACKAGE - DIMENSIONS APPLY IN BOTH " X " AND " Y " DIRECTIONS. Z INCHES (.148) .106 .091 .091 .026 .016 .041 .189 MILLIMETERS (3.75) 2.70 2.30 2.30 0.65 0.40 1.05 4.80
Contact Information
Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805) 498-2111 Fax: (805) 498-3804 www.semtech.com
(c) 2008 Semtech Corporation
18

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