SGM4056 Datasheet, PDF (11/19 Pages) SG Micro Corp – High Input Voltage Charger

SGM4056
Trickle
CC
4.2V
I_REF
2.55V
18% I_REF
Charge Current
High Input Voltage Charger
CV
Charge Voltage
74% I_REF
I_MIN
CHG
CHG Indication
Time
OPERATION
Figure 3. Typical Charge Profile
The SGM4056 charges a Li-ion battery using a CC/CV
profile. The constant current I_REF is set with the external
resistor R_IREF (see Figure 1) and the constant voltage is
fixed at 4.2V. If the battery voltage is below a typical
2.55V trickle charge threshold, the SGM4056 charges the
battery with a trickle current of 18% of I_REF until the
battery voltage rises above the trickle charge threshold.
Fast charge CC mode is maintained at the rate
determined by programming I_REF until the cell voltage
rises to 4.2V. When the battery voltage reaches 4.2V, the
charger enters a CV mode and regulates the battery
voltage at 4.2V to fully charge the battery without the risk
of over charge. Upon reaching an end-of-charge (EOC)
current, the charger indicates the charge completion with
the CHG pin, but the charger continues to output the
4.2V voltage. Figure 3 shows the typical charge
waveforms after the power is on.
The EOC current level I_MIN is programmable with the
external resistor R_IMIN (see Figure 1). The CHG pin turns
to low when the trickle charge starts and rises to high
impedance at the EOC. After the EOC is reached, the
charge current has to rise to typically 74% I_REF for the
CHG pin to turn on again, as shown in Figure 3. The
current surge after EOC can be caused by a load
connected to the battery.
A thermal foldback function reduces the charge current
anytime when the die temperature reaches typically
115℃. This function guarantees safe operation when the
printed circuit board (PCB) is not capable of dissipating
the heat generated by the linear charger. The SGM4056
accepts an input voltage up to 26.5V but disables
charging when the input voltage exceeds the OVP
threshold, typically 6.8V for SGM4056-6.8 and 10.5V for
SGM4056-10.5, to protect against unqualified or faulty
AC adapters.
PPR Indication
The PPR pin is an open-drain output to indicate the
presence of the AC adapter. Whenever the input voltage
is higher than the POR threshold, the PPR pin turns on
the internal open-drain MOSFET to indicate a logic low
signal, independent on the EN pin input. When the
internal open-drain FET is turned off, the PPR pin leaks
less than 20µA current. When turned on, the PPR pin is
able to sink at least 15mA current under all operating
conditions. The PPR pin can be used to drive an LED
(see Figure 1) or to interface with a micro- processor.
SG Micro Corp
11
www.sg-micro.com