NJW4100M datasheet(13/19 Pages) NJRC

13 / 19 page

NJW4100

-13 -

Ver.2005-01-20

■FEATURE DESCRIPTION (CONTINUED)

7. Reference Voltage Block (VREF pin)

This block generates 1.24V and 4.2V reference voltages. The VREF pin outputs 1.24V. In addition to the IC internal

reference voltage, this is also used as a reference voltage for charge current setting and temperature detection setting.

8. Power Block,

Under Voltage Lockout Circuit (UVLO) Block (V

+ pin, GND pin)

An integrated

Under Voltage Lockout circuit prevents IC malfunction when power is turned on or off. This circuit

incorporates a 200mV hysteresis width to prevent chattering.

As required, insert a bypass capacitor near the IC's V

+ pin when there is power line noise or when wires are long.

9. LED Block (LED-R pin, LED-G pin)

The 2 LEDs can indicate charge status. (Figure 5)

The LED drive circuit is an open collector output configuration.

Therefore, it is easy to set a constant LED drive current with resistance values.

The expression for setting the current that flows through the LEDs is shown below.

ILED-G ≒ (Vcc - VF-LED - VOL-G) / RLED

ILED-R ≒ (Vcc - VF-LED - VOL-R) / RLED

Figure 5. LED Drive Circuit

LED-G

LED-R

Input

VF-LED

ILED

RLED

NJW4100M Datasheet(PDF) 13 Page - New Japan Radio