Using the High-Input-Voltage Travel Charger, Rev. 1.0
8 Freescale Semiconductor
Test Setup with the Evaluation Board
The absolute maximum voltage at the GRN and RED pin is 12V. When applying higher than 12V
input voltage, select BAT to power the LED.
The JP3 pin header allows the user to disable the MC34674 when shorting pins 1 and 2. Leaving
it open enables the MC34674.
The JP4 pin header links the BAT pin and the external battery connector. It allows the user to
measure the charging current from the MC34674 into the battery with a current meter between
pin 1 and pin 2. The default setting is to short pins 1 and 2.
JP5 lets the user use the potentiometer P1 on the evaluation board to simulate the NTC
thermistor. When it is shorted, turning the P1 can evaluate the voltage threshold at TEMP pin.
When it is opened, an NTC must be connected to the NTC pad of the board. The NTC interface
resistors R1 and R2 must be replaced by the other value resistors with respect to the selected
NTC
7.2 Connector Pads
There are 9 connecting pads (J1 to J9 with the corresponding names) on the evaluation board
to let the user to simply connect the board to their system. The GND pads link power ground of
the MC34674. The INPUT pad connects an external DC power supply to the evaluation board.
The GRN, RED, EN, TEMP, and VREF pad link to the corresponding pins of the MC34674. The
VBAT pad connects the positive pole of the Li+ battery being charged.
7.3 Test points
The KIT34674EPEVBE evaluation board provides 7 signal test points and 3 ground test points
for users to conveniently hook up multi-meters and oscilloscope probes to evaluate the
MC34674. The test points connect the pins of the MC34674 with the same name directly.
8 Test Setup with the Evaluation Board
The test setup is shown in Figure 7. Connect a DC power source with a larger than 1.5A current
limit to the INPUT pad on the evaluation board. Connect the positive and negative polarities of
the Li+ battery to the VBAT pad and the GND pad on the evaluation board respectively. Use a
current meter and a voltage meter to measure the charge current and the battery voltage
respectively. Turn on the power supply and the evaluation board starts to charge the battery.
