User's Manual Part 1

MC75 Hardware Interface Description
Strictly confidential / Draft
s
MC75_V00.190a Page 67 of 91 15.02.2005
Please note that the reference voltages listed in Table 16 are the values measured directly
on the MC75 module. They do not apply to the accessories connected.
Table 16: Signal description
Function Signal name IO Signal form and level Comment
V
I
max = 4.3V
V
I
typ = 3.8V
V
I
min = 3.2V during Tx burst on board
I  2A, during Tx burst
Power
supply
BATT+ I
n Tx = n x 577µs peak current every
4.616ms
Five pins of BATT+ and GND
must be connected in parallel
for supply purposes because
higher peak currents may
occur.
Minimum voltage must not fall
below 3.2V including drop,
ripple, spikes.
Power
supply
GND Ground Application Ground
VCHARGE I
V
I
min = 1.015 * V
BATT+
V
I
max = 5.45V
This line signalizes to the
processor that the charger is
connected.
If unused keep pin open.
BATT_TEMP I
Connect NTC with R
NTC
 10kΩ @ 25°C to
ground. See Section 3.4.1 for B value of
NTC.
Battery temperature
measurement via NTC
resistance.
NTC should be installed
inside or near battery pack to
enable proper charging and
deliver temperature values.
If unused keep pin open.
ISENSE I
V
I
max = 4.65V
∆V
I
max to V
BATT+
= +0.3V at normal
condition
ISENSE is required for
measuring the charge current.
For this purpose, a shunt
resistor for current
measurement needs to be
connected between ISENSE
and VSENSE.
If unused connect pin to
VSENSE.
VSENSE I
V
I
max = 4.5V
VSENSE must be directly
connected to BATT+ at
battery connector or external
power supply.
Charge
Interface
CHARGEGATE O
V
O
max = 5.5V
I
O
max = 1mA
Control line to the gate of
charge FET
If unused keep pin open.
External
supply
voltage
VEXT O
Normal mode:
V
O
min = 2.75V
V
O
typ = 2.93V
V
O
max = 3.05V
I
O
max = -50mA
VEXT may be used for
application circuits, for
example to supply power for
an SD Card.
If unused keep pin open.
Not available in Power-down
mode. The external digital
logic must not cause any
spikes or glitches on voltage
VEXT.