IP2312 Single-Cell Lithium Battery Synchronous Switch Buck Charging IC
Features
- Synchronous switch step-down charging
- Charging efficiency 94% (3.7V/2A)
- Maximum charging current 3A
- Charging current adjustable via external resistor
- Automatic input current adjustment, compatible with small current adapters
- Supports 4.20V/4.30V/4.35V/4.4V battery
- Supports charging NTC temperature protection
- Supports LED charging status indication
- Built-in power MOS
- 750KHz switching frequency, supports 1uH inductor
- Input overvoltage and undervoltage protection
- IC over-temperature protection
- Charging timeout protection
- ESD 4KV
Applications
- Single-cell lithium battery/lithium-ion battery charging
Introduction
The IP2312 is a 5V input synchronous switch buck charge management IC for single-cell lithium batteries. It integrates power MOS and adopts a synchronous switching architecture, requiring minimal peripheral components for a compact and cost-effective solution. The IP2312 operates at a 750KHz switching frequency, offers a maximum charging current of 3A, and achieves 94% efficiency at 3.7V/2A. The charging current is adjustable via an external resistor. It intelligently adjusts input current to prevent adapter overload. The IP2312 is available in an ESOP8 package.
Pin Definition
IP2312 Pin Diagram
The IP2312 is available in an ESOP8 package. The pin diagram shows the following pins:
| Pin Name | Pin Number | Pin Description |
|---|---|---|
| D1 | 1 | LED driver pin/battery type selection (IP2312_VSET) |
| TEST | 2 | Test pin, connect 1K resistor to the positive terminal of the battery |
| D2 | 3 | LED driver pin |
| NTC | 4 | NTC temperature protection, connect NTC resistor |
| ONE | 5 | Connect the positive terminal of the lithium battery |
| ICHG | 6 | Charging current setting pin |
| SW | 7 | DC-DC switch pin |
| COME | 8 | 5V charging input pin |
| EPAD | -- | GND |
Limit Parameters
Stresses greater than those listed in the Absolute Maximum Ratings section may cause permanent damage to the device. Excessive exposure time may affect reliability and service life.
| Parameter | Symbol | Value | Unit |
|---|---|---|---|
| Port input voltage range | COME | -0.3 ~ 6.5 | V |
| Junction temperature range | TJ | -40 ~ 150 | °C |
| Storage temperature range | Tstg | -60 ~ 150 | °C |
| Thermal resistance (junction to ambient) | θJA | 60 | °C/W |
| Human Body Model (HBM) ESD | ESD | 4 | KV |
Recommended Working Conditions
Device operating characteristics cannot be guaranteed beyond these conditions.
| Parameter | Symbol | Minimum Value | Typical Value | Maximum Value | Unit |
|---|---|---|---|---|---|
| Input voltage | COME | 4.5 | 5 | 5.5 | V |
| Charging current | ICHRG | 0 | 2.1 | 3 | A |
Electrical Characteristics
Unless otherwise specified, TA=25°C, L=1uH, VIN =5V, VBAT=3.7V
| Parameter | Symbol | Test Conditions | Smallest Value | Typical Value | Maximum Value | Unit |
|---|---|---|---|---|---|---|
| Input voltage | COME | 4.5 | 5 | 5.5 | V | |
| Charging target voltage | VTRGT | 4.15 | 4.2 | 4.23 | V | |
| Default charging current | ICHRG- | VIN =5V, VBAT =3.7V, RICHG = NC | 1.8 | 2.1 | 2.4 | A |
| Charging switching frequency | fs | VIN =5V, VBAT =2.7V | 650 | 750 | 850 | KHz |
| Trickle charge current | ITRKL | 50 | 100 | 300 | mA | |
| Trickle cutoff voltage | VTRKL | 2.9 | 3.0 | 3.1 | V | |
| Recharge threshold | TOP | 4.08 | 4.1 | 4.13 | V | |
| Charging end time | TEND | 20 | 24 | 28 | Hour | |
| Input undervoltage protection voltage | VIN-UVLO | 4.4 | 4.5 | 4.6 | V | |
| Input overvoltage protection voltage | VIN-OVP | 5.5 | 5.6 | 5.7 | V | |
| PMOS on-resistance | rDSON | 30 | 35 | 40 | mΩ | |
| NMOS on-resistance | 25 | 30 | 35 | mΩ | ||
| Battery input standby current | ISTB | VIN =0V, VBAT =3.7V | 30 | 40 | 50 | µA |
| LED display driving current | IL1 | 3 | 5 | 10 | mA | |
| Thermal shutdown temperature (rising) | TOTP rising temperature | 110 | 135 | 150 | °C | |
| Thermal shutdown recovery temperature (drop) | TOTP drop temperature | 70 | 85 | 100 | °C |
Function Description
Block Diagram
The IP2312 integrates a Buck synchronous switching step-down charge controller with a switching frequency of 750KHz, 5V input, and an efficiency of 94% at 3.7V/2A output. The internal block diagram shows the main components including PMOS, NMOS, Charger driver, System Control, and LED driver, connected to the SW, ICHG, NTC, ONE, D1, and D2 pins.
Charging Process
The IP2312 uses a complete CC/CV (Constant Current/Constant Voltage) charging mode.
- When the battery voltage is below 3V, it enters trickle charging mode with a current of 100mA.
- When the battery voltage is above 3V, it enters constant current charging mode with the set current.
- When the battery voltage approaches 4.2V and the charging current drops below 300mA, it enters constant voltage charging mode. It checks every 4 minutes if the battery voltage is above 4.15V; if so, charging stops, otherwise it continues.
- If the battery is fully charged and the voltage drops below 4.1V, it will restart charging.
Charging Protection
The IP2312 offers comprehensive protection features, including a built-in soft-start to prevent inrush current faults, and integrated input overvoltage/undervoltage, overtemperature, charging timeout, and NTC temperature protection for stable operation.
- VIN Input Undervoltage Protection: When VIN (pin 8) drops below 4.5V, the charging current is reduced to maintain VIN at 4.5V, preventing adapter overload.
- VIN Input Overvoltage Protection: When VIN (pin 8) exceeds 5.6V, charging is stopped.
- NTC Temperature Protection: Charges normally between 0-43°C. Charging current is halved above 43°C and charging stops above 45°C. If NTC is not needed, connect the NTC pin to ground with a 51K resistor. The NTC pin must not be left floating. The device discharges 20µA from the NTC pin and monitors voltage drop across an external resistor to determine temperature.
- Charging Timeout Protection: Charging is forcibly stopped if it exceeds 24 hours.
- Over-temperature Protection: Charging stops if the chip temperature reaches 135°C and resumes when it drops to 85°C.
Battery Type Selection (IP2312_VSET Model)
The IP2312 defaults to 4.2V lithium batteries. The IP2312_VSET model supports selecting battery full voltages (4.2V, 4.3V, 4.35V, 4.4V) by connecting pull-down resistors (RVSET) to the D1 pin (pin 1). This pin also serves as an LED display output.
| RVSET on D1 (pin 1) | Battery Type Selection (Battery Full Voltage) |
|---|---|
| NC | 4.2V |
| 43K 1% | 4.3V |
| 75K 1% | 4.35V |
| 100K 1% | 4.4V |
Constant Current Charging Current Setting
The constant current charging current (ICC) is set by the external resistor RICHG connected to the ICHG pin (pin 6). The formula is ICC = 135000 / RICHG.
| ICHG Terminal Resistance RICHG | Battery Terminal Constant Current Charging Current ICC |
|---|---|
| 135KΩ | 1A |
| 91KΩ | 1.5A |
| 45KΩ | 3A |
| NC | 2.1A (Default) |
Charging LED Indication
The IP2312 supports 1 or 2 LED indicators.
Two-light mode:
- D1: Bright when charging; turns off when battery is fully charged.
- D2: Flashes at 0.5Hz during charging process; bright when battery is full.
One-light mode:
- D1: Behavior depends on configuration.
Typical Application Schematics
The schematic shows a typical application circuit for the IP2312. Key components include the IP2312 IC, VIN input (4.5-5.5V), battery connection (VBAT), inductor (L1=1uH), resistors for current setting (RICHG) and battery type selection (RVSET), capacitors for filtering (C1, C2, C3, C4, C6), and an NTC thermistor (RNTC) for temperature monitoring. The schematic illustrates the two-light and one-light LED indicator modes and the current setting mechanism.
Component Notes:
- R2 and C6 are used to absorb high-voltage pulses when the charger is inserted, protecting the IP2312.
- C1 and C2 should be placed close to the IP2312, with their ground connected to the EPAD ground.
- The EPAD ground loop should be as small as possible.
- For NTC function, the NTC pin must be connected to ground with a 51K resistor if not used; it must not be left floating.
Package Information
The IP2312 is supplied in an ESOP8 package. The following table provides the package dimensions in millimeters:
| Symbol | Min | Name | Max |
|---|---|---|---|
| A | 1.65 | ||
| A1 | 0.05 | 0.15 | |
| A2 | 1.30 | 1.50 | |
| A3 | 0.60 | 0.70 | |
| b | 0.39 | 0.48 | |
| b1 | 0.38 | 0.43 | |
| c | 0.21 | 0.25 | |
| c1 | 0.19 | 0.21 | |
| D | 4.70 | 5.10 | |
| E | 5.80 | 6.20 | |
| E1 | 3.70 | 4.10 | |
| (It) | 1.27BSC | ||
| L | 0.50 | 0.80 | |
| (L1) | 1.05BSC | ||
| i | |||
| D1 | 2.09 | ||
| E2 | 2.09 |
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Yingjixin Technology Co., Ltd. reserves the right to make changes to its products and services. Customers should obtain the latest information before ordering. Yingjixin Technology Co., Ltd. assumes no obligation for application assistance or customer product design; customers are responsible for their product applications and ensuring compliance with all legal, regulatory, and safety requirements. Customers must develop their products with adequate expertise to foresee and mitigate risks. Copying of product manuals or datasheets is only permitted with unaltered content and relevant authorizations. Yingjixin will update this document periodically, and product parameters may vary. This document does not constitute an express or implied warranty or authorization. Reselling Yingjixin products with parameter discrepancies constitutes an unfair business practice, and Yingjixin is not liable for such misrepresentations.