Electronic Components Datasheet Search |
|
MAX1811 Datasheet(PDF) 6 Page - Maxim Integrated Products |
|
MAX1811 Datasheet(HTML) 6 Page - Maxim Integrated Products |
6 / 8 page USB-Powered Li+ Charger 6 _______________________________________________________________________________________ USB* PORT 4.35V TO 5.5V IN MAX1811 SYSTEM LOAD BATT SINGLE Li+ CELL *WHEN USING WALL ADAPTER, IN VOLTAGE RANGE IS FROM 4.35V TO 6.5V. Figure 2. System Configuration Detailed Description Charger-Control Circuitry The voltage/current regulator consists of a voltage con- trol loop, a current control loop, and a thermal control loop (Figure 1). Use the SELV input to set the battery regulation voltage to a 4.1V or 4.2V single Li+ cell. The current and thermal loops are internally compensated and require no external compensation. The outputs from all loops drive an internal linear regulator. The thermal loop modulates the current loop by limiting the charge current if the die temperature exceeds +125°C. The MAX1811 is in current mode when the BATT volt- age is below the regulation set point and in voltage mode when the BATT voltage is near the regulation set point. The CHG output indicates whether the part is in current mode (CHG = low) or voltage mode (CHG = high impedance). Battery voltages less than 2.5V acti- vate a 43mA preconditioning mode (CHG = high impedance). Normal charging resumes when the bat- tery voltage exceeds 2.5V. System Configuration The MAX1811 is designed to operate seamlessly with a universal serial bus (USB) port. In a typical design, the USB connects to the MAX1811 input, and the MAX1811 drives the load and charges the battery when enabled. Charge-Current Selection The MAX1811 charges a single cell Li+ battery in either 100mA or 500mA modes. The MAX1811 expects the system to poll the USB host to determine if the USB is capable of providing 100mA or 500mA and regulates the charging current accordingly (Figure 2). This is to maintain compatibility with both powered and unpow- ered USB hosts. A powered USB host is capable of providing 500mA, and an unpowered USB hub is limit- ed to only 100mA. Drive SELI low to set the charge current to the 100mA mode. Use a 10k Ω pulldown resistor to ground on SELI, if necessary, to ensure that the MAX1811 defaults to the 100mA mode in the event that no logic signal is present. Drive SELI high to increase the charge current to the 500mA mode only if the polled USB port can pro- vide the required current. Thermal-Control Circuitry The thermal loop limits the MAX1811 die temperature to +125°C by reducing the charging current as neces- sary. The MAX1811 can operate normally with the ther- mal loop active. This is not a fault condition and can be used continuously. The power dissipated by the inter- nal power FET is determined by (VIN - VBATT) ✕ ICHG. The power dissipation rating for the thermally enhanced 8-pin SO package is 1.4W at +50°C ambient (assuming a 1in2 PC board radiating area), which is the maximum ambient temperature at which most Li+ battery manu- facturers allow charging. The 1.4W power dissipation may never be reached due to the MAX1811’s thermal regulation loop. Applications Information USB Output Voltage The minimum voltage to a USB-powered device may be as low as 4.35V when cable and connector drops are considered (Figure 3). The MAX1811 is optimized for operation at these low input voltage levels. USB hubs may also provide as much as 5.5V. At high input voltages (5.5V) and low cell voltages (2.7V), the MAX1811’s thermal loop may limit the charge current until the cell voltage rises. |
Similar Part No. - MAX1811 |
|
Similar Description - MAX1811 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |