APL3200 Просмотр технического описания (PDF) - Anpec Electronics

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APL3200

Dual-Input, USB/AC Adapter, 1-Cell Li+ Charger with OVP and Thermal Regulation

Anpec Electronics 

APL3200

Function Description (Cont.)

USB Charging Current

The charging current from the USB source is selected by

USEL. A USB source can supply a maximum of 100mA or

500mA. USB hosts and powered hubs typically supply

500mA while unpowered hubs supply 100mA. A logic low

on USEL selects a 100mA maximum charging current. A

logic high on USEL selects a 500mA maximum charging

current.

is in voltage mode. If the APL3200 is charging from a

USB source with USEL low, charge-done occurs when

the charger enters voltage mode.

After the APL3200 enunciates the charge-done signal, it

keeps operating in voltage mode without turning off the

charger and stopping the safety counter.

Thermal Regulation

DC Charging Current

When charging from the DCLV input, the DCI voltage (V )

SET

and the resistor (R ) connected from this pin to the

SET

GND set the charging current (ICHG_DC) as the following

equation :

ICHG_DC = KSET x VSET

RSET

The charging current set factor (K ) is shown in the

SET

Electricl Characteristics. The DCI regulation voltage is

reduced by thermal regulation function. Connecting DCI

to the GND results in a limited 1.8A charging current.

Battery Full Indication

The APL3200 reports the charge-done status on STAT1

and STAT2 pins when the charging current falls below a

percentage of the set fast-charge current (Table 2) and

the charger is in voltage mode (V near 4.2V).

BATT

Table 2 Battery Full Indication

CHARGING SOURCE

DCLV Charging

USB Charging

(500mA, USEL=high)

USB Charging

(100mA, USEL=low)

CHARGE-DONE

CURRENT THRESHOLD

12.5% of Fast-charge current

and charger in voltage mode

125mA and charger in voltage

mode

Charger in voltage mode

When charging from a DC source, charge-done occurs

when ICHG_DC falls to 12.5% of the current set by RSET and

the charger is in voltage mode (VBATT near 4.2V). When

charging from a USB source with USEL high, charge-

done occurs when ICHG_USB falls to 125mA and the charger

On-chip thermal limiting in the APL3200 simplifies PC

board layout and allows charging rates to be automatically

optimized without constraints imposed by worstcase

minimum battery voltage, maximum input voltage, and

maximum ambient temperature. When the APL3200

thermal limit is reached, the charger does not shut down

but simply reduces charging current. This allows the

board design to be optimized for compact size and typical

thermal conditions. The APL3200 reduces charging

current to keep its die temperature below +120°C. The

APL3200’s QFN package includes a bottom metal plate

that reduces thermal resistance between the die and the

PC board. The external pad should be soldered to a large

ground plane. This helps dissipate power and keeps the

die temperature below the thermal limit. The APL3200’s

thermal regulator is set for a +120°C die temperature.

External Thermistor Monitor (THRM)

The APL3200 features an internal window comparator to

monitor battery pack temperature or ambient temperature

with an external negative temperature coefficient

thermistor. In typical systems, temperature is monitored

to prevent charging at ambient temperature extremes

(below 0°C or above +50°C). When the temperature

moves outside these limits, charging is stopped. If the

VTHERM returns to its normal window, charging resumes.

Connect THRM to the GND when not using this feature.

The THRM block diagram is detailed in Figure 1. Note

that the temperature monitor at THRM entirely separates

from the on-chip temperature limiting discussed in the

Thermal Regulation section. The input thresholds for the

THRM input are 0.74 x VREF for the COLD trip point and

0.29 x VREF for the HOT trip point.

Copyright © ANPEC Electronics Corp.

15

Rev. A.5 - Apr., 2009

www.anpec.com.tw

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