SAA1504T/N1 Просмотр технического описания (PDF) - Philips Electronics
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SAA1504T/N1 Datasheet PDF : 16 Pages
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Philips Semiconductors
Safety IC
Objective specification
SAA1504T
PINNING
SYMBOL PIN
DESCRIPTION
VSS
1 ground supply
DO
2 output to gate of discharge power FET
CO
3 output to gate of charge power FET
VM
4 negative sense input
ST
5 status output
n.c.
6 not connected
CEXT
7 connection for external delay capacitor
VCC
8 positive battery sense input
handbook, halfpage
VSS 1
8 VCC
DO 2
7 CEXT
SAA1504T
CO 3
6 n.c.
VM 4
5 ST
MGS970
Fig.2 Pin configuration.
FUNCTIONAL DESCRIPTION
The basic function of the SAA1504T is to protect a single
Li-ion cell against overcharge and overdischarge for
reasons of life time and safety. The voltage across the cell
terminals (Vbat) is monitored continuously and compared
to an accurate internal reference voltage.
The circuit diagram (see Fig.3) of a Li-ion battery pack
shows the SAA1504T and 2 power NMOS transistors
which are connected in anti series. Both transistors must
have their backgate connected to their source, resulting in
2 backgate diodes in anti series.
The timing diagram (see Fig.6) shows the detection levels
for the various modes of operation.
Battery voltage between 2.6 and 4.18 V
The safety IC is in the normal operating mode for
Vbat = 2.6 to 4.18 V, a charge or discharge current below
the current-protection level and a junction temperature
below the temperature protection activation level. In this
mode transistors SW1 and SW2 are driven with an
elevated supply voltage (with a charge pump) which
guarantees a low on-resistance in the main current path.
This is important for fully utilizing the high energy density
of the Li-ion battery technology.
handbook, full pagewidth
2000 Mar 07
+ charger/load
Vbat
R1
1 kΩ
C1
0.47 µF
CEXT
7
C2
VSS 1
VCC
8
ST
5
SW2
DO
2 SAA1504T
− charger/load
SW1
CO
3
4
VM
MGS971
Fig.3 Safety IC connection diagram.
4
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