ISL6255AHRZ-T Intersil, ISL6255AHRZ-T Datasheet - Page 15

• Manufacturer Part Number: ISL6255AHRZ-T
• Description: IC BATTERY CHRGR NOTEBOOK 28-QFN
• Manufacturer: Intersil

Specifications of ISL6255AHRZ-T

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion), Lithium-Polymer (Li-Pol)
• Voltage - Supply: 7 V ~ 25 V
• Operating Temperature: -10°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 28-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

current-sense resistor. The highest accuracy of ±3% is
achieved with 100mV current-sense threshold voltage for
ACLIM = VREF, but it has the highest power dissipation. For
example, it has 400mW power dissipation for rated 4A AC
adapter and 1W sensing resistor may have to be used. ±4%
and ±6% accuracy can be achieved with 75mV and 50mV
current-sense threshold voltage for ACLIM = Floating and
ACLIM = GND, respectively.
A low pass filter is suggested to eliminate the switching
noise. Connect the resistor to CSIN pin instead of CSIP pin
because CSIN pin has lower bias current and less influence
on the current-sense accuracy.
AC Adapter Detection
Connect the AC adapter voltage through a resistor divider to
ACSET to detect when AC power is available, as shown in
Figure 15. ACPRN is an open-drain output and is high when
ACSET is less than V
above V
Where I
V
hysteresis is I
and 4.4µA (max).
DC Adapter Detection
Connect the DC adapter voltage like aircraft power through a
resistor divider to DCSET to detect when DC power is
available, as shown in Figure 16. DCPRN is an open-drain
output and is high when DCSET is less than V
active low when DCSET is above V
are given by:
Where I
V
hysteresis is I
and 4.4µA (max).
Current Measurement
Use ICM to monitor the input current being sensed across
CSIP and CSIN. The output voltage range is 0 to 2.5V. The
V
V
V
V
th
ACSET
th
th rise
th fall
DCSET
,
,
,
,
rise
fall
=
=
=
hys
hys
th,fall
⎛
⎜
⎜
⎝
=
⎛
⎜
⎜
⎝
= 1.24V (min), 1.26V (typ) and 1.28V (max). The
= 1.24V (min), 1.26V (typ) and 1.28V (max). The
R
R
R
R
⎛
⎜
⎝
⎛
⎜
⎝
8
9
8
9
R
--------- -
R
is the ACSET input bias current hysteresis and
R
--------- -
R
is the DCSET input bias current hysteresis and
14
15
+
. V
+
14
15
hys
hys
1
1
+
⎞
• ⎟ ⎟
⎠
⎞
• ⎟ ⎟
⎠
+
th,rise
R
1
R14, where I
V
1
V
⎞
⎟
⎠
8
⎞
⎟
⎠
ACSET
ACSET
•
, where I
•
V
th,rise
V
and V
DCSET
DCSET
−
, and active low when ACSET is
I
th,fall
hys
hys
15
–
hys
I
R
hys
= 2.2µA (min), 3.4µA (typ)
8
are given by:
= 2.2µA (min), 3.4µA (typ)
R
th,fall
14
. V
th,rise
th,rise
and V
ISL6255, ISL6255A
, and
th,fall
voltage of ICM is proportional to the voltage drop across
CSIP and CSIN, and is given by the following equation:
where I
ICM has ±3% accuracy. It is recommended to have an RC
filter at the ICM output for minimizing the switching noise.
LDO Regulator
VDD provides a 5.0V supply voltage from the internal LDO
regulator from DCIN and can deliver up to 30mA of current.
The MOSFET drivers are powered by VDDP, which must be
connected to VDDP as shown in Figure 15. VDDP connects
to VDD through an external low pass filter. Bypass VDDP
and VDD with a 1µF capacitor.
Shutdown
The ISL6255, ISL6255A features a low-power shutdown
mode. Driving EN low shuts down the ISL6255, ISL6255A. In
shutdown, the DC/DC converter is disabled, and VCOMP
and ICOMP are pulled to ground. The ICM, ACPRN and
DCPRN outputs continue to function.
EN can be driven by a thermistor to allow automatic
shutdown of the ISL6255, ISL6255A when the battery pack
is hot. Often a NTC thermistor is included inside the battery
pack to measure its temperature. When connected to the
charger, the thermistor forms a voltage divider with a
resistive pull-up to the VREF. The threshold voltage of EN is
1.0V with 60mV hysteresis. The thermistor can be selected
to have a resistance vs temperature characteristic that
abruptly decreases above a critical temperature. This
arrangement automatically shuts down the ISL6255,
ISL6255A when the battery pack is above a critical
temperature.
Another method for inhibiting charging is to force CHLIM
below 85mV (typ).
Supply Isolation
If the voltage across the adapter sense resistor R2 is
typically greater than 8mV, the P-channel MOSFET
controlled by SGATE is turned on reducing the power
dissipation. If the voltage across the adapter sense resistor
R2 is less than 3mV, SGATE turns off the P-channel
MOSFET isolating the adapter from the system bus.
Battery Power Source Selection and Aircraft
Power Application
The battery voltage is monitored by CSON. If the battery
voltage measured on CSON is less than the adapter voltage
measured on DCIN, then the P-channel MOSFET controlled by
BGATE turns off and the P-channel MOSFET controlled by
SGATE is allowed to turn on when the adapter current is high
enough. If it is greater, then the P-channel MOSFET controlled
by SGATE turns off and BGATE turns on the battery discharge
P-channel MOSFET to minimize the power loss. Also, the
ICM
=
INPUT
19.9 I
•
INPUT
is the DC current drawn from the AC adapter.
•
R
2
May 23, 2006
FN9203.2