SC810

SC810 SEMTECH | Alldatasheet

Document overview

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Technical content

Features

Constant voltage — 4.2V, 1% regulation Fast-charge current regulation — 15% at 70mA, 9% at 700mA Three mode charging — current regulation, voltage regulation, and thermal limiting Input voltage protection — 30V Current-limited charging support — reduces power dissipation in charger IC Instantaneous CC-to-CV transition for faster charging Three termination options — fl oat-charge, automatic re-charge, or forced re-charge to keep the battery topped-off after termination without fl oat-charging Soft-start reduces adapter load transients High operating voltage range permits use of unregulated adapters Complies with CCSA YD/T 1591-2006 Space saving 2x2x0.6 (mm) MLPD package WEEE and RoHS compliant

Applications

Description

The SC810 is a linear single-cell Li-ion battery charger in a 6 lead 2x2 MLPD Ultra-thin package. The input will survive sustained input voltage up to 30V to protect against hot plug overshoot and faulty charging adapters. Charging begins automatically when a valid input source is applied. Thermal limiting protects the SC810 from excessive power dissipation. It can be programmed to turn off when charging is complete or to continue operat- ing as an LDO regulator while fl oat-charging the battery. The input will charge with an adapter operating in voltage regulation or in current-limit to obtain the lowest possible power dissipation by pulling the input voltage down to the battery voltage. The maximum fast-charge current setting is 1A. Charge current is programmed with a single resistor. Pre- charge and termination current are fi xed at 20% and 10%, respectively, of the programmed fast-charge current. Charge current steps up to the programmed value (soft starts) to reduce load transients on the charging adapter. Device Load Battery Pack 2.2 μF VADAPTER 2.2 μF VIN IPRGMGND STATB ENB BAT SC810 Typical Application Circuit February 26, 2008

© 2008 Semtech Corporation SC810 Pin Confi guration Marking Information

Ordering Information

SC810ULTRT(1)(2) MLPD-UT-6 2×2 SC810EVB Evaluation Board Notes: (1) Available in tape and reel only. A reel contains 3,000 devices. (2) Lead-free package only. Device is WEEE and RoHS compliant. TOP VIEW T

6 ENB

MLPD-UT6; 2x2, 6 LEAD θJA = 68°C/W yw = Date Code

© 2008 Semtech Corporation SC810 Exceeding the above specifi cations may result in permanent damage to the device or device malfunction. Operation outside of the parameters specifi ed in the Electrical Characteristics section is not recommended. NOTES: (1) Tested according to JEDEC standard JESD22-A114-B. (2) 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. Absolute Maximum Ratings BAT + 0.3 ESD Protection Level Recommended Operating Conditions Thermal Information Test Conditions: VVIN= 4.75V to 5.25V; VBAT = 3.7V; Typ values at 25°C; Min and Max at -40°C < TA < 85°C, unless specifi ed. Parameter Symbol Conditions Min Typ Max Units VIN Operating Voltage (1) VOP 4.60 5.00 8.20 V VIN Under-Voltage Lockout Rising Threshold VTUVLO-R 4.30 4.45 4.60 V VIN Under-Voltage Lockout Falling Threshold (2) VTUVLO-F VVIN > VBAT 2.70 2.85 3.00 V VIN OVP Rising Threshold VT OVP-R 9.6 V VIN OVP Falling Threshold VT OVP-F 8.2 V VIN OVP Hysteresis VT OVP-H VTOVP-R - VTOVP-F 50 mV VIN Charging Disabled Quiescent Current IqVIN_DIS VENB = VBAT 23 m A VIN Charging Enabled Quiescent Current IqVIN_EN VENB = 0V, excluding IBAT and IIPRGM 23 m A CV Regulation Voltage V CV IBAT = 50mA, -40°C ≤ TJ ≤ 125°C 4.16 4.20 4.24 V CV Voltage Load Regulation V CV_LOAD Relative to VCV @ 50mA, 1mA ≤ IBAT ≤ 1A, -40°C ≤ TJ ≤ 125°C -20 10 mV Battery Leakage Current lBAT_V0 VVIN = 0V 0.1 1 μA lBAT_DIS VVIN = 5V, VENB = 2V 0.1 1 μA lBAT_MON VVIN = 5V, VBAT = VCV, ENB not connected 0.1 1 μA Re-charge Threshold VT ReQ VCV - VBAT 60 100 140 mV Pre-charge Threshold (rising) VT PreQ 2.85 2.90 2.95 V

Electrical Characteristics

© 2008 Semtech Corporation SC810 Parameter Symbol Conditions Min Typ Max Units IPRGM Programming Resistor R IPRGM 2.05 29.4 kΩ Fast-Charge Current, adapter mode I FQ_AD RIPRGM = 2.94kΩ, VTPreQ < VBAT < VCV 643 694 745 mA Pre-Charge Current I PreQ RIPRGM = 2.94kΩ, 1.8V < VBAT < VTPreQ 105 139 173 mA Termination Current I TERM RIPRGM = 2.94kΩ, VBAT = VCV 59 69 80 mA Dropout Voltage V DO IBAT = 700mA, 0°C ≤ TJ ≤ 125°C 0.40 0.60 V IPRGM Fast-charge Regulated Voltage V IPRGM_FQ VVIN = 5.0V, VTPreQ < VBAT < VCV 2.04 V IPRGM Pre-charge Regulated Voltage V IPRGM_PQ 1.8V < VBAT < VTPreQ 0.408 V IPRGM Termination Threshold Voltage VT IPRGM_TERM VBAT = VCV (either input selected) 0.204 V Thermal Limiting Threshold Temperature TTL 130 °C Thermal Limiting Rate i T 50 mA/ °C ENB Input High Voltage V IH 1.6 V ENB Input Mid Voltage V IM 0.7 1.3 V ENB Input Low Voltage V IL 0.3 V ENB Input High-range Threshold Input Current IIH_TH ENB current required to pull ENB from floating midrange into high range 23 50 μA ENB Input High-range Sustain Input Current IIH_SUS Current required to hold ENB in high range, Min VIH ≤ VENB ≤ VBAT, Min VIH ≤ VBAT ≤ 4.2V 0.3 1 μA ENB Input Mid-range Load Limit I IM Input will float to mid range when this load limit is observed. -5 5 μA ENB Input Low-range Input Current I IL 0V ≤ VENB ≤ Max VIL -25 -12 μA ENB Input Leakage I ILEAK VVIN = 0V, VENB = VBAT = 4.2V 1 μA STATB Output Low Voltage V STAT_LO ISTAT_SINK = 2mA 0.5 V STATB Output High Current I STAT_HI VSTAT = 5V 1 μA Electrical Characteristics (continued) Notes: (1) Maximum operating voltage is the maximum Vsupply as defined in EIA/JEDEC Standard No. 78, paragraph 2.11. This is the inpu t voltage at which the charger is guaranteed to begin operation. (2) Sustained operation to VT UVLO-F ≤ V VIN is guaranteed only if a current limited charging source applied to VIN is pulled below VT UVLO-R by the charging load; forced VIN voltage below VTUVLO-R in some cases may result in regulation errors or other unexpected behavior.

© 2008 Semtech Corporation SC810 Typical Characteristics CV Line Regulation CV Load Regulation CV Temperature Regulation CC FQ Line Regulation CC FQ VBAT Regulation CC FQ Temperature Regulation 55 . 566 . 577 . 584.18 4.184 4.188 4.192 4.196 4.2 4.204 VVIN (V) VBAT (V) TA = 25οC, IBAT = 50mA 0 100 200 300 400 500 600 700 8004.18 4.184 4.188 4.192 4.196 4.2 4.204 IBAT (mA) VBAT (V) TA = 25οC, VVI N = 5V 4.5 5 5.5 6 6.5 7 7.5 8696 700 704 708 712 716 720 VVIN (V) IBAT (mA) TA = 25οC, VBAT = 3.7V, RIPRGM = 2.94kΩ -40 -20 0 20 40 60 80 100 1204.18 4.184 4.188 4.192 4.196 4.2 4.204 Ambient Temperature ( o VBAT (V) VVI N = 5V, IBAT = 50mA 696 700 704 708 712 716 720 VBAT (V) IBAT (mA) TA = 25οC, VVI N = 5V, RIPRGM = 2.94kΩ -40 -20 0 20 40 60 80 100 120 696 700 704 708 712 716 720 Ambient Temperature ( o IBAT (mA) VVI N = 5V, VBAT = 3.7V, RIPRGM = 2.94kΩ

© 2008 Semtech Corporation SC810 Typical Characteristics (continued) CC PQ Line Regulation CC PQ Temperature Regulation IFQ vs. RIPRGM IPQ vs. RIPRGM -40 -20 0 20 40 60 80 100 120140 144 148 152 156 160 Ambient Temperature ( o IBAT (mA) VVI N = 5V, VBAT = 2.6V, RIPRGM = 2.94kΩ 55 . 566 . 577 . 58140 144 148 152 156 160 VVIN (V) IBAT (mA) TA = 25οC, VBAT = 2.6V, RIPRGM = 2.94kΩ 2 6 10 14 18 22 26 300 200 400 600 800 1000 RIPRGM (kΩ) IBAT (mA) VVI N = 5V, VBAT = 3.7V, TA = 25οC 2 6 10 14 18 22 26 300 120 160 200 RIPRGM (kΩ) IBAT (mA) VVI N = 5V, VBAT = 2.6V, TA = 25οC

© 2008 Semtech Corporation SC810 CC-to-CV Battery Voltage and Current Re-Charge Cycle Battery Voltage and Current 610 630 650 670 690 710 IBAT (mA) 4.17 4.18 4.19 4.2 4.21 Time (min) VBAT (V) 850mAhr battery, RIPRGM = 2.94kΩ, VVI N = 5.0V, TA = 25οC VBAT IBAT 100 150 200 250 300 350 400 450 IBAT (mA) 0.5 1.5 2.5 3.5 4.5 Time (hrs) VBAT (V), Internal Power Dissipation (W) 850mAhr battery, RIPRGM = 2.94kΩ, VVI N = 5.0V, Load = 10mA VBAT IBAT Discharge hours 2 - 6 omitted. Charging Cycle Battery Voltage and Current P re-Charging Battery Voltage and Current 100 200 300 400 500 600 700 800 IBAT (mA) 0 2 4 6 8 1 01 21 41 61 82 02 2.25 2.5 2.75 3.25 3.5 3.75 Time (s) VBAT (V) 850mAhr battery, RIPRGM = 2.94kΩ, VVI N = 5.0V, TA = 25οC VBAT IBAT 100 200 300 400 500 600 700 IBAT (mA) Time (hrs) VBAT (V), Internal Power Dissipation (W) 850mAhr battery, RIPRGM = 2.94kΩ, VVI N = 5.0V, TA = 25οC VBAT IBAT Typical Characteristics (continued)

© 2008 Semtech Corporation SC810 Pin Descriptions Pin # Pin Name Pin Function 1 VIN Supply pin — connect to charging adapter (wall adapter or USB). This is a high voltage (30V) pin. 2S T A T B Status output pin — This open-drain pin is asserted (pulled low) when a valid charging supply is connected to VIN, and a charging cycle begins. It is released when the termination current is reached, indicating that charging is complete. STATB is not asserted for re-charge cycles.

3 GND Ground

4 IPRGM

Fast-charge and pre-charge current programming pin — Fast-charge current is programmed by connecting a resistor from this pin to ground. Pre-charge current is 20% of fast-charge current. The charging termination current threshold is 10% of the IPRGM programmed fast-charge current. 5B A T Charger output — connect to battery positive terminal. Combined device enable/disable — Logic high disables the device. Tie to GND to enable charging with indefi nite fl oat-charging. Float this pin to enable charging without fl oat-charge upon termination. Note that this pin must be grounded if the SC810 is to be operated without a battery connected to BAT. T Thermal Pad Pad is for heat sinking purposes — not connected internally. Connect exposed pad to ground plane using multiple vias.

© 2008 Semtech Corporation SC810 Block Diagram CC CV Termination STATB IPRGM GND BAT VCV = 4.2V VIREF VIN V_Adapter To System Load Lithium- Ion Single Cell Battery Pack RIPRGM Connect to BAT or to regulated supply VTIPRGM_TERM Precharg, CC/CV & Termination Controller, Logical State Machine ENB Tri-level Control VTENB_HIGH = ~1.50V VTENB_LOW = ~0.551V Thermal Limiting Die Temperature VT_CT

© 2008 Semtech Corporation SC810 Charger Operation The SC810 is a single cell Li-ion battery charger. It imple- ments a Constant Current, Constant Voltage, Constant Temperature (CC/CV/CT) charging algorithm. When an input supply is fi rst detected, a charge cycle is initiated and the STATB open-drain output goes low. If the battery voltage is less than the pre-charge threshold voltage, the pre-charge current is supplied. Pre-charge current is 20% of the programmed fast-charge current. When the battery voltage exceeds the pre-charge thresh- old, typically within seconds for a standard battery with a starting cell voltage greater than 2V, the fast-charge Constant Current (CC) mode begins. The charge current soft-starts in three steps (20%, 60%, and 100% of pro- grammed fast-charge current) to reduce adapter load transients. CC current is programmed by the IPRGM resis- tance to ground. The charger begins Constant Voltage (CV) regulation when the battery voltage rises to the fully-charged single- cell Li-ion regulation voltage (V CV), nominally 4.2V. In CV regulation, the output voltage is regulated, and as the battery charges, the charge current gradually decreases. The STATB output goes high when I BAT drops below the termination current threshold, which is 10% of the IPRGM pin programmed fast-charge current, regardless of the mode selected. This is known as charge termination. Optional Float-charging or Monitoring Depending on the state of the ENB input, upon termina- tion the SC810 either operates indefi nitely as a voltage regulator (fl oat-charging) or it turns off its output. If the output is turned off upon termination, the device enters the monitor state. In this state, the output remains off until the BAT pin voltage decreases by the re-charge threshold (VT ReQ). A re-charge cycle then begins automati- cally and the process repeats. A forced re-charge cycle can also be periodically commanded by the processor to keep the battery topped-off without fl oat-charging. See the Monitor State section for details. Re-charge cycles are not indicated by the STATB pin. Charging Input Pin Properties Glitch fi ltering is performed on the VIN pin, so an input voltage that is ringing across its Under-Voltage Lockout (UVLO) threshold will not be recognized until the ringing has ceased. The UVLO rising threshold is set higher than the voltage of a fully charged Li-ion single cell battery, ensuring that only a charging source capable of fully charging the battery has been applied. If the charging current loads the adapter beyond its current limit, the input voltage will be pulled down to just above the battery voltage. The UVLO falling threshold is set close to the battery voltage pre-charge threshold to permit low- dissipation charging from a current limited adapter. Constant Current Mode Fast-charge Current Programming The Constant Current (CC) mode is active when the battery voltage is above VTPreQ and less than VCV. The pro- grammed CC regulation fast-charge (FQ) current is inversely proportional to the resistance between IPRGM and GND according to the equation 1000R VI IPRGM Typ_IPRGM FQ u The fast-charge current can be programmed for a minimum of 70mA and a maximum of 995mA, nominally. Current regulation accuracy is dominated by gain error at high current settings, and off set error at low current set- tings. The range of expected fast-charge output current versus programming resistance is shown in Figures 1a and 1b. The figures show the nominal current versus nominal R IPRGM resistance as the center plot and two theo- retical limit plots indicating maximum and minimum current versus nominal programming resistance. These plots are derived from models of the expected worst-case contribution of error sources depending on programmed current. The current range includes the uncertainty due to 1% tolerance resistors. The dots on each plot indicate the currents obtained with standard value 1% tolerance resistors. Figures 1a and 1b show low and high resistance ranges, respectively. Pre-charge Mode This mode is automatically enabled when the battery voltage is below the pre-charge threshold voltage (VT PreQ), typically 2.8V. Pre-charge current conditions the battery for fast charging. The pre-charge current value is Applications Information

© 2008 Semtech Corporation SC810 Applications Information (continued) The GPIO port is configured as an input to select mid-range. ENB can also be permanently grounded to select low- range or left unconnected to select mid-range if it will not be necessary to change the level selection. The equivalent circuit looking into the ENB pin is a vari- able resistance, minimum 15kΩ, to an approximately 1V source. The input will fl oat to mid range whenever the external driver sinks or sources less than 5μA, a common worst-case characteristic of a high impedance or a weak pull-up or pull-down GPIO confi gured as an input. The driving GPIO must be able to sink or source at least 75μA to ensure a low or high state, respectively, although the drive current is typically far less. (See the Electrical Characteristics table.) If the ENB input voltage is permitted to fl oat to mid-range, the charger is enabled but it will turn off its output follow- ing charge termination and will enter the monitor state. This state is explained in the next section. Mid-range can be selected either by floating the input (sourcing or sinking less than 5μA) or by being externally forced such that V ENB falls within the midrange limits specifi ed in the Electrical Characteristics table. When driven low (V ENB < Max VIL), the charger is enabled and will continue to float-charge the battery following termination. If the charger is already in monitor state fol- lowing a previous termination, it will exit the monitor state and begin fl oat-charging. When ENB is driven high (V ENB > Min V IH), the charger is disabled and the ENB input pin enters a high impedance state, suspending tri-level functionality. The specified high level input current I IH is required only until a high level is recognized by the SC810 internal logic. The tri- level float circuitry is then disabled and the ENB input becomes high impedance. Once forced high, the ENB pin will not fl oat to mid range. To restore tri-level operation, the ENB pin must fi rst be pulled down to mid or low range (at least to V ENB < Max V IM), then, if desired, released (by reconfi guring the GPIO as an input) to select mid-range. If the ENB GPIO has a weak pull-down when confi gured as an input, then it is unnecessary to drive ENB low to restore tri-level operation; simply confi gure the GPIO as an input. When the ENB selection changes from high-range to mid- or low-range, a new charge cycle begins and STATB goes low. Note that if a GPIO with a weak pull-up input confi gura- tion is used, its pull-up current will fl ow from the GPIO into the ENB pin while it is fl oating to mid-range. Since the GPIO is driving a 1V equivalent voltage source through a resistance (looking into ENB), this current is small — pos- sibly less than 1 μA. Nevertheless, this current is drawn from the GPIO peripheral power supply and, therefore, from the battery after termination. (See the next section, Monitor State.) For this reason, it is preferable that the GPIO chosen to operate the ENB pin should provide a true high impedance (CMOS) configuration or a weak pull- down when confi gured as an input. When pulled below the fl oat voltage, the ENB pin output current is sourced from VIN, not from the battery. Monitor State If the ENB pin is fl oating, the charger output and STATB pin will turn off and the device will enter the monitor state when a charge cycle is complete. If the battery voltage falls below the re-charge threshold (V CV - VReQ) while in the monitor state, the charger will automatically initiate a re- charge cycle. The battery leakage current during monitor state is no more than 1μA over temperature and typically less than 0.1μA at room temperature. While in the monitor state, the ENB tri-level input pin remains fully active, and although in midrange, is sensitive to both high and low levels. The SC810 can be forced from the monitor state (no float-charging) directly to float- charging operation by driving ENB low. This operation will turn on the charger output, but will not assert the STATB output. If the ENB pin is again allowed to float to mid- range, the charger will remain on only until the output current becomes less than the termination current, and charging terminates. The SC810 turns off its charging output and returns to the monitor state within a millisec- ond. This forced re-charge behavior is useful for periodically testing the battery state-of-charge and topping-off the battery, without float-charging and without requiring the battery to discharge to the auto- matic re-charge voltage. ENB should be held low for at least 1ms to ensure a successful forced re-charge.

© 2008 Semtech Corporation SC810 Forced re-charge can be requested at any time during the charge cycle, or even with no charging source present, with no detrimental effect on charger operation. This allows the host processor to schedule a forced re-charge at any desired interval, without regard to whether a charge cycle is already in progress, or even whether a charging source is present. Forced re-charge will neither assert nor release the STATB output. Status Output The STATB pin is an open-drain output. It is asserted (driven low) as charging begins after a valid charging input is applied and the VIN voltage is greater than the input UVLO level and less than the OVP level. STATB is also asserted as charging begins after the ENB input returns to either of the enable voltage ranges (mid or low voltage) from the disable (high voltage) range. STATB is subse- quently released when the termination current is reached to indicate end-of-charge, when the ENB input is driven high to disable charging, or when the input voltage is removed. If the battery is already fully charged when a charge cycle is initiated, STATB is asserted, and remains asserted for approximately 750μs before being released. The STATB pin is not asserted for automatic re-charge cycles. The STATB pin may be connected to an interrupt input to notify a host controller of the charging status or it can be used as an LED driver. Logical CC-to-CV Transition The SC810 diff ers from monolithic linear single cell Li-ion chargers that implement a linear transition from CC to CV regulation. The linear transition method uses two simul- taneous feedback signals — output voltage and output current — to the closed-loop controller. When the output voltage is suffi ciently below the CV regulation voltage, the influence of the voltage feedback is negligible and the output current is regulated to the desired current. As the battery voltage approaches the CV regulation voltage (4.2V), the voltage feedback signal begins to infl uence the control loop, which causes the output current to decrease although the output voltage has not reached 4.2V. The output voltage limit dominates the controller when the battery reaches 4.2V and eventually the controller is entirely in CV regulation. The soft transition eff ectively reduces the charge current below that which is permitted Applications Information (continued) for a portion of the charge cycle, which increases charge time. In the SC810, a logical transition is implemented from CC to CV to recover the charge current lost due to the soft transition. The controller regulates only current until the output voltage exceeds the transition threshold voltage. It then switches to CV regulation. The transition voltage from CC to CV regulation is typically 5mV higher than the CV regulation voltage, which provides a sharp and clean transition free of chatter between regulation modes. The diff erence between the transition voltage and the regula- tion voltage is termed the CC/CV overshoot. While in CV regulation, the output current sense remains active. If the output current exceeds the programmed fast-charge current by 5%, the controller reverts to current regulation. The logical transition from CC to CV results in the fastest possible charging cycle that is compliant with the speci- fi ed current and voltage limits of the Li-ion cell. The output current is constant at the CC limit, then decreases abruptly when the output voltage steps from the overshoot voltage to the regulation voltage at the transition to CV control. Thermal Limiting Device thermal limiting is the third output constraint of the Constant Current, Constant Voltage, “Constant” Temperature (CC/CV/CT) control. This feature permits a higher input OVP threshold, and thus the use of higher voltage or poorly regulated adapters. If high input voltage results in excessive power dissipation, the output current is reduced to prevent overheating of the SC810. The thermal limiting controller reduces the output current by i T ≈ 50mA/ºC for any junction temperature TJ > TTL. When thermal limiting is inactive, TJ = TA + VΔ IFQ θJA, where VΔ is the voltage difference between the VIN pin and the BAT pin. However, if TJ computed this way exceeds TTL, then thermal limiting will become active and the thermal limiting regulation junction temperature will be TJTL = TA + VΔ I(TJTL) θJA,

© 2008 Semtech Corporation SC810 Applications Information (continued) where I(TJTL) = IFQ − iT (TJTL − TTL). Combining these two equations and solving for T JTL, the steady state junction temperature during active thermal limiting is JAT JATLTFQA JTL iV1 TiIVTT T T Although the thermal limiting controller is able to reduce output current to zero, this does not happen in practice. Output current is reduced to I(T JTL), reducing power dissi- pation such that die temperature equilibrium T JTL is reached. While thermal limiting is active, all charger functions remain active and the charger logical state is preserved. Operating a Charging Adapter in Current Limit In high charging current applications, charger power dis- sipation can be greatly reduced by operating the charging adapter in current limit. The SC810 supports adapter- current-limited charging with a low UVLO falling threshold and with internal circuitry designed for low input voltage operation. To operate an adapter in current limit, R IPRGM is chosen such that the programmed fast-charge current IFQ exceeds the current limit of the charging adapter IAD-LIM. Note that if IAD-LIM is less than 20% of I FQ, then the adapter voltage can be pulled down to the battery voltage while the battery voltage is below the pre-charge threshold. In this case, care must be taken to ensure that the adapter will maintain its current limit below 20% of I FQ at least until the battery voltage exceeds the pre-charge threshold. Failure to do so could permit charge current to exceed the pre-charge current while the battery voltage is below the pre-charge threshold. This is because the low input voltage will also compress the pre-charge threshold inter- nal reference voltage to below the battery voltage. This will prematurely advance the charger logic from pre- charge current regulation to fast-charge regulation, and the charge current will exceed the safe level recom- mended for pre-charge conditioning. The low UVLO falling threshold ( VT UVLO-F ) permits the adapter voltage to be pulled down to just above the battery voltage by the charging load whenever the adapter current limit is less than the programmed fast- charge current. The SC810 should be operated with adapter voltage below the rising selection threshold (VT UVLO-R ) only if the low input voltage is the result of adapter current limiting. This implies that the VIN voltage fi rst exceeds VTUVLO-R to begin charging, and is subsequently pulled down to just above the battery voltage by the charging load. Interaction of Thermal Limiting and Current Limited Adapter Charging To permit the charge current to be limited by the adapter, it is necessary that the fast-charge current be programmed greater than the maximum adapter current, (I AD-LIM). In this confi guration, the CC regulator will operate with its pass device fully on (in saturation, also called “dropout”). The voltage drop from VIN to BAT is determined by the product of the minimum R DS-ON of the pass device multiplied by the adapter supply current. In dropout, the power dissipation in the SC810 is PILIM = (minimum R DS-ON) x (I AD-LIM)2. Since minimum R DS-ON does not vary with battery voltage, dropout power dissi- pation is constant throughout the CC portion of the charge cycle while the adapter remains in current limit. The SC810 junction temperature will rise above ambient by P ILIM x θJA. If the device temperature rises to the tem- perature at which the thermal limiting control loop limits charging current (rather than the current being limited by the adapter), the input voltage will rise to the adapter regulation voltage. The power dissipation will increase so that the thermal limit regulation will further limit charge current. This will keep the adapter in voltage regulation for the remainder of the charge cycle. To ensure that the adapter remains in current limit, the internal device temperature must never rise to T TL. This implies that θJA must be kept small enough to ensure that TJ = TA + (PILIM × θJA) < TTL. Short Circuit Protection The SC810 can tolerate a BAT pin short circuit to ground indefi nitely. The current into a ground short is approxi- mately 10mA.

© 2008 Semtech Corporation SC810 A short to ground on the IPRGM current programming pin will prevent startup. During charging, a short to ground applied to the IPRGM pin forces the SC810 into reset, turning off the output and holding it off until the short is removed. When the IPRGM short to ground is removed, the charger begins normal operation automatically without input power cycling. Over-Current Protection Over-current protection is provided in all modes of opera- tion, including CV regulation. The output current is limited to either the programmed pre-charge current limit value or the fast-charge current limit value, depending on the voltage at the output. Input Over-Voltage Protection The VIN pin is protected from over-voltage to at least 30V above GND. When the input voltage exceeds the Over- Voltage Protection (OVP) rising threshold (VT OVP-R ), charging is halted. When the input voltage falls below the OVP falling threshold (VT OVP-F), charging resumes. An OVP fault turns off the STATB output. STATB is turned on again when charging restarts. The OVP threshold has been set relatively high to permit the use of poorly regulated adapters. Such adapters may output a high voltage until loaded by the charger. A too-low OVP threshold could prevent the charger from ever turning on and loading the adapter to a lower voltage. If the adapter voltage remains high despite the charging load, the fast thermal limiting feature will immediately reduce the charging current to prevent overheating of the SC810. This behavior is illustrated in Figure 4, in which V BAT = 3.0V, I FQ = 700mA, and V VIN is stepped from 0V to 8.1V. Initially, power dissipation in the SC820 is 3.6W. Notice the BAT output current is rapidly reduced to limit the internal die temperature, then continues to decline as the circuit board gradually heats up, further reducing the conduction of heat from the die to the ambient environ- ment. The fast thermal limiting feature ensures compliance with CCSA YD/T 1591-2006, Telecommunication Industrial Standard of the People’s Republic of China — Technical Requirements and Test Method of Charger and Interface for Mobile Telecommunication Terminal, Section 4.2.3.1. 1s/div VVIN (2V/div) VVIN ,VBAT=0V— IBAT (100mA/div) IBAT=0mA— VVIN=8.1V, VBAT=3.0V IBAT=700mA (Initially), PDISSIPATION=3.6W (Initially) VBAT (2V/div) Figure 4 — Thermal Limiting Example Operation Without a Battery The SC810 can be operated as a 4.2V LDO regulator without the battery present, for example, factory testing. If this use is anticipated, the output capacitance C BAT should be at least 2.2μF to ensure stability. To operate the charger without a battery, the ENB pin must be driven low or grounded. Capacitor Selection Low cost, low ESR ceramic capacitors such as the X5R and X7R dielectric material types are recommended. The BAT pin capacitor, C BAT, range is 1μF to 22μF. The VIN input capacitors, C VIN is typically between 0.1μF and 2.2μF, however a larger value will not degrade performance. Capacitance must be evaluated at the expected bias voltage, rather than the zero-volt capacitance rating. PCB Layout Considerations Layout for linear devices is not as critical as for a switching regulator. However, careful attention to detail will ensure reliable operation. Place input and output capacitors close to the device for optimal transient response and device behavior. Connect all ground connections directly to the ground plane. If there is no ground plane, connect to a common local ground point before connecting to board ground near the GND pin. Attaching the part to a larger copper Applications Information (continued)

internal ground and power planes. external circuit is illustrated in Figure 5. Figure 5. Dynamic selection of low and high charge fi ed by a change in the IPRGM pin resistor.

© 2008 Semtech Corporation SC810 (LASER MARK) INDICATOR PIN 1 N MIN aaa bbb b e L N D A DIM MILLIMETERS NOM DIMENSIONS MAXNOM INCHES MIN MAX LxN NOTES: CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS TERMINALS.2. .003 .007 .075 .010 .079 .000 .020 (.006) 0.08 0.25 .012 .083 0.18 1.90 .024 .002 0.00 0.50 2.10 0.30 2.00 0.05 0.60 (0.152) .004 0.10 0.50 BSC.020 BSC aaa C SEATING PLANE A bbb C A B B e C D E A .061 E bxN Outline Drawing — MLPD-UT6 2x2

© 2008 Semtech Corporation Semtech Corporation Power Management Products Division

200 Flynn Road, Camarillo, CA 93012

Phone: (805) 498-2111 Fax: (805) 498-3804 www.semtech.com Contact Information SC810 Land Pattern — MLPD-UT6 2x2 H K 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. .031 .067 0.80 1.70 .106 .020 .012 .030 2.70 0.30 0.75 0.50 (.077) .047 1.20 (1.95) NOTES: THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD SHALL BE CONNECTED TO A SYSTEM GROUND PLANE. FUNCTIONAL PERFORMANCE OF THE DEVICE. FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR INCHES DIMENSIONS G K H X Y P Z C DIM MILLIMETERS (C) G Z P X R .006 0.15 R Y