PT8A2803ZEE

PT8A2803 PERICOM | Alldatasheet

Document overview

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Technical content

Features

• A Constant-Current / Constant-Voltage Linear Charger for Single-Cell Li-ion/Polymer Batteries
• Integrated Pass Element and Current Sensor
• Highly-Integrated, Requiring No External FETs or Blocking Diode
• ±0.5% 4.2V Voltage Accuracy at Room Temperature. ±1% All Temperatures. (Available with 4.1V and 4.36V options upon request)
• Programmable Charge Current 50mA to 500mA
• Programmable End-Of-Charge Current by Current Recharge Algorithm
• Pre-Charge for Fully Discharged Batteries
• Less Than 1µA Leakage Current Of the Battery when No Input Power Attached or Charger Disabled
• Power Present and Charge Status Indications
• Thermal Regulation on Charging Current to Prevent Over-Heat
• Available with 8-pin 2x3mm TDFN Package

Applications

• Cell-phones, PDA, MP3, MP4, PMP
• Standalone Chargers
• Bluetooth Applications

Description

The PT8A2803 is a fully integrated single-cell Li- ion/Polymer battery charger. The charger operates in a constant-current-constant-voltage (CC/CV) charging profile without employing external FETs and blocking diodes. The fast charge current and end-of-charge (EOC) current can be easily programmed by modifying two external resistors. When the battery is deeply discharged to lower than 2.8V, the charger firstly pre-charges the battery with typically 20% of the programmable fast charge current. When the charge current is reduced to the programmed EOC current level (almost works completely in a constant-voltage (CV) mode), an EOC indication is displayed through the CHG pins. PT8A2803 is protected by thermal regulation technology to prevent the IC from over-heat during charging. Two status indication pins ( PPR and CHG ), which are both implemented as an open-drain outputs, can be used to drive LEDs or work as logic interface to a microprocessor. When no adapter is attached or when the charger is disabled, the leakage current from battery cell is less than 1µA typically.

Ordering Information

Ordering No. Package PT8A2803ZEE Lead free and Green 8-pin TDFN Notes: z E = Pb-free and Green z Adding X Suffix= Tape/Reel

12-03-0002 PT0324-1 03/06/12 PT8A2803 500mA Li-ion/Polymer Battery Charger Block Diagram 200K POR Charge Control DI E 115°C VREF VBAT VOSVREF TE MP VIN PPR EN CH G IREF IMIN GND BA T EN Figure 1 Block diagram of PT8A2803 Pin Assignment TDFN 2x3mm Pin Description Pin I/O Name Descriptions 1 I/O VIN Supply Input.

2 O PPR Power Present Active-Low Open Drain Power Status Indicator

3 O CHG Charge Active-Low Open Drain Charge Status Indicator

4 I EN Enable Active-Low Input

5 I/O GND Ground

6 I IMIN End-Of-Charge Current Setting Input

7 I IREF Charge Current Setting Input

8 O BAT Battery Terminal

discharged to lower than 2.55V, PT8A2803 firstly pre-charges the battery with 20% of the programmed fast charge current. voltage at 4.2V with safe & small current. Figure 2 shows the typical charge profile with the EOC/reset event. resistor RIMIN (see Figure 3/4). The CHG signal turns to LOW when pre-charge starts and rises to HIGH when EOC is reached. Figure 2. The current surge after EOC can be caused by a load connected to the battery. operation especially when the printed circuit board (PCB) is not effective in leaking out heat generated by the linear charger. internal open-drain MOSFET to indicate a logic LOW signal. turned off, the PPR pin should leak less than 1µA current. interface to a microprocessor (see Figure 4). used to interface with a microprocessor. equivalent to logic LOW and the chip is enabled by default. (Electrical Specifications). Where RIMIN is usually in kΩ.

12-03-0002 PT0324-1 03/06/12 PT8A2803 500mA Li-ion/Polymer Battery Charger BAT pin Always connect the BAT pin to a single-cell Li-ion/Polymer battery in parallel with a 1µF (or larger) X5R ceramic capacitor for decoupling and guaranteeing system stability. When the EN pin is pulled to logic HIGH, the BAT output is disabled. The PT8A2803 relies on a battery for stability and is not guaranteed to be stable if the battery is not connected. Dropout Voltage When the input voltage is low while the battery voltage is high, the charging current may not be maintained according to the equation IMIN (mA) = 4180/R IMIN due to a limited internal on- resistance (R DS(ON)) of the internal pass element. The worst resistance of the pass FET is about 1.2 Ω at the maximum operating temperature, thus if tested with 500mA current and 4.2V battery voltage, constant current could still be maintained when the input voltage is below 4.62V. Thermal Foldback The bottom big exposed pad in 5DFN package is used for thermal foldback. For reducing the chip ambient temperature as much as possible, it is recommended to connect as much copper as possible to this pad either on the component layer or other layers through thermal vias. The thermal regulation function starts to reduce the charge current when the internal temperature reaches a typical value of 115°C. ICHG IMIN Battery Voltage Charging Current V A 2.55V 4.2V CC Mode CV Mode CHG Charging (LED ON) EOC (LED OFF) Recharge (LED ON) IRECHG IPRE Added loading Figure 2 PT8A2803 Typical Charge Profile

12-03-0002 PT0324-1 03/06/12 PT8A2803 500mA Li-ion/Polymer Battery Charger Maximum Ratings θJC (°C/W)=4.5 Recommended Operating Conditions Sym Parameter Min Typ Max Unit VIN Operating Voltage 4.3 - 5.5 V Programmable Current - 50 - 500 mA TA Operating temperature -30 - +85 °C Electrical Specifications Typical values are at V IN=5V and T A =25°C. All maximum and minimum values are at T A = -30 °C to +85 °C, unless otherwise noted. Parameter Sym Conditions Min Typ Max Units POWER-ON RESET Rising POR Threshold V POR 3.3 3.9 4.3 V Falling POR Threshold V POR VBAT=3.0V, use PPR to indicate the output 3.1 3.6 4.15 V VIN-VBAT OFFSET VOLTAGE Rising Edge V OS - 90 150 mV Falling Edge V OS VBAT=4.0V, use CHG pin to indicate the comparator output 10 50 - mV STANDBY CURRENT BAT pin sink current I STBY Charger disabled or the input is floating - 1 - µA DC Supply Current I DC Charger disabled - 300 400 µA DC Supply Current I DC Charger enabled - 500 700 µA VOLTAGE REGULATION Power FET “ON” Resistance R DS(ON) VBAT=3.8V, charge current=0.5A, R IREF =8kΩ - 0.6 - Ω CHARGE CURRENT Constant Charge Current I CHG R IREF=29.4kΩ, VBAT = 2.8–4.0V 135 150 165 mA Precharge Charge Current I PRE R IREF=29.4kΩ, VBAT = 2.4V 18 25 32 mA End of Charge Current I MIN R IMIN=137kΩ 20 30 40 mA EOC Rising Threshold I RECHG R IREF =29.4kΩ 90 100 130 mA PRECHARGE CHARGE THRESHOLD Precharge Threshold Voltage V PRE - 2.45 2.55 2.65 V Precharge Voltage Hysteresis V PREHYS - 40 100 150 mV INTERNAL TEMPERATURE MONITORING Thermal regulation threshold (Note) T FOLD - 100 115 130 °C LOGIC INPUT AND OUTPUTS EN Pin Logic Input High VENH - 1.3 - - V EN Pin Logic Input Low VENL - - - 0.5 V EN Pin Internal Pull Down Resistance REN - 100 200 400 k Ω CHG Pin Sink Current When LOW ICHGOL V CHG=1V 10 20 - mA CHG Pin Leakage Current When HIGH ICHGOH V CHG=5.5V - - 1 µA PPR Pin Sink Current When LOW IPPROL V PPR=1V 10 20 - mA PPR Pin Leakage Current When HIGH IPPROH V PPR=5.5V - - 1 µA Note: This parameter is guaranteed by design, not tested. Note: Stresses greater than those listed under MAXIMUM RATINGS may cause permanent damage to th e device. This is a stress rating only and functional operation of the device at thes e or any other condi- tions above those indicated in the operational sec-tions of this specification is not implied. Exposureto absolute maximum rating conditions for extended periods may affect reliabilit

12-03-0002 PT0324-1 03/06/12 PT8A2803 500mA Li-ion/Polymer Battery Charger

Application Information

The input capacitor is employed to decouple the power supply from load transients and suppress noise from power lines. Typically, a 1µF X5R ceramic capacitor is recommended to be placed very close between the VIN pin and GND pin to stabilize the operation during the start up, especially when the input supply is passing the POR threshold and the VIN-BAT comparator offset voltage. Once passing through the POR threshold, there is a voltage hysteresis to provide sufficient guard band from noise or load transient to trigger the system to reset. Output Capacitor Selection The criterion for selecting the output capacitor is to maintain the stability of the charger as well as to bypass any transient load current. Typically, a minimum capacitance of 1µF X5R ceramic capacitor is recommended and sufficient for stabilizing the system. For systems that may happen to occasionally see high load transi ents, the output capacitor may be increased to further bypass a ny ripples so caused. Charge Current Limit During the constant-current (CC) charging mode, the charging current is primarily determined by I CHG as calculated in previous formula. However, the actual charge current is the CC mode could also be limited by other factors as described by below Figure 5. When the input (VIN) and output (V BAT) voltage are too close to each other, the on-resistance of the internal pass element may limit the amount of current that passes through it. For example, the solid curve describes a typical case in which the battery voltage is 4.0V and the charge current (ICHG) is set at 350mA. When the input voltage is sufficiently higher than the battery voltage but has not increased the die temperature over the thermal limit yet, the charging current is accurately regulated at 350mA. Figure 5: PT8A2803 Charge Current Limits In CC Mode When the input voltage is reduced (or the battery voltage is in creases towards the input voltage), the charge current is limite d by the on-resistance of the pass element. Therefore, it is recommended to employ sufficiently high input voltage for applications that require constant charging current over the entire charging peri od. But for applications that n eeds to minimize the heat dissipa tion, a current-limiting adapter maybe applied to maintain constant charging current at whole charging phase. In addition, if the input voltage increases, the charge current may also be reduced due to the thermal foldback function. The h igh voltage drop across the pass element incr eases the power dissipation therein and thus causing the die temp erature to increase significantly. Layout Guidance The PT8A2803 employs thermally-enhanced DFN package, which have an exposed thermal pad at its bottom side. It is recommended to connect as much copper as possible between the exposed pad and PCB to make it effective in dissipating the heat away from the die. For applications requiring high charging current, the thermal impedance should be further reduced by employing more layers of copper to connect with the exposed pad through thermal via. Input Power Sources PT8A2803 works with different types of AC /DC adapter or USB port (any type) with no special requirements. For PT8A2803, it works with input voltage ranges from 4.3V to 5.5V for normal operation but the maximum input voltage is 7V.

12-03-0002 PT0324-1 03/06/12 PT8A2803 500mA Li-ion/Polymer Battery Charger Mechanical Information ZEE (Lead free and Green TDFN 2x3mm) Pericom Semiconductor Corporation y 1-800-435-2336 y www.pericom.com X. XX X. XX DENOTES DIMENSIONS IN MILLIMETERS Note: 1) Controlling dimens ions in millimeters .