Operation
The JTM8010 is a single-cell lithium-ion battery charger using a constant-current/constant-voltage
algoritJTM. It can deliver up to 800mA of charge current (using a good thermal PC board layout) with a
final float voltage accuracy of ±1%. The JTM8010 includes an internal P-channel power MOSFET and
thermal regulation circuitry. No blocking diode or external current sense resistor is required and the
JTM8010 is capable of operating from a USB power source.
 
Normal Charge
Charging begins when EN is low, the voltage at the VIN pin rises above the 4.5V and a program resistor
is connected from the ISET pin to ground. If the VOUT pin voltage is below 2.9V, the charger enters
trickle charge mode. In this mode, the JTM8010 supplies approximately 1/10 the programmed charge
current to bring the battery voltage up to a safe level for full current charging.
When the BAT pin voltage rises above 2.9V, the charger enters constant-current mode, where the
programmed charge current is supplied to the battery. When the VOUT pin approaches the final float
voltage (4.2V), the JTM8010 enters constant-voltage mode, and the charge current begins to decrease.
 
VIN Bypass Capacitor
Many types of capacitors can be used for input bypassing; however, caution must be exercised when
using multilayer ceramic capacitors. Because of the self resonant and high Q characteristics of some
types of ceramic capacitors, high voltage transients can be generated under some start-up conditions,
such as connecting the charger input to a live power source. Adding a 1.5W resistor in series with an
X5R ceramic capacitor will minimize start-up voltage transients.