ISL9222AIRTZ-T Intersil, ISL9222AIRTZ-T Datasheet - Page 7

• Manufacturer Part Number: ISL9222AIRTZ-T
• Description: IC VOLT CHARGER HI INPUT 8-TDFN
• Manufacturer: Intersil

Specifications of ISL9222AIRTZ-T

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion), Lithium-Polymer (Li-Pol)
• Voltage - Supply: 4.5 V ~ 6.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-TDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ISL9222AIRTZ-TTR

event. A tantalum capacitor is a good choice for its high
ESR, providing damping to the voltage transient. Multi-layer
ceramic capacitors, however, have a very low ESR and
hence when chosen as input capacitors, a 1Ω series resistor
must be used (as shown in “Typical Applications” on page 4)
to provide adequate damping.
Output Capacitor Selection
The criteria for selecting the output capacitor is to maintain
the stability of the charger as well as to bypass any transient
load current. The minimum capacitance is a 1µF X5R
ceramic capacitor. The actual capacitance connected to the
output is dependent on the actual application requirement.
Charge Current Limit
The actual charge current in CC mode is limited by several
factors in addition to the set I
for the charge current in CC mode. The charge current is
limited by the ON-resistance of the pass element (power
P-channel MOSFET) if the input and the output voltage are
too close to each other. The solid curve shows a typical case
when the battery voltage is 4.0V and the charge current is
set to 700mA. The non-linearity on the R
due to the increased resistance at higher die temperatures. If
the battery voltage increases to higher than 4.0V, the entire
curve moves towards the right side. As the input voltage
increases, the charge current may be reduced due to the
thermal foldback function. The limit caused by the thermal
limit is dependent on the thermal impedance. As the thermal
impedance increases, the thermal-limited curve moves
towards left, as shown in Figure 3.
FIGURE 3. CHARGE CURRENT LIMITS IN THE CC MODE
700
4.0
LIMITED
R
ON
4.5
INPUT VOLTAGE (V)
INCREASES
5.0
V
REF
BAT
7
INCREASES
. Figure 3 shows three limits
R
IREF
5.5
INCREASES
ON
θ
JA
-limited region is
6.0
or T
THERMAL
LIMITED
A
6.5
ISL9222A
Layout Guidance
The ISL9222A uses a thermally-enhanced TDFN package
that has an exposed thermal pad at the bottom side of the
package. The layout should connect as much as possible to
copper on the exposed pad. Typically, the component layer
is more effective in dissipating heat. The thermal impedance
can be further reduced by using other layers of copper
connecting to the exposed pad through a thermal via array.
Each thermal via is recommended to have 0.3mm diameter
and 1mm distance from other thermal vias.
Input Power Sources
The input power source is typically a well-regulated wall
cube with 1-meter length wire or a USB port. The input
voltage ranges from 4.25V to 6.5V under full-load and
unloaded conditions. The ISL9222A can withstand up to 28V
on the input without damaging the IC. If the input voltage is
higher than typically 7.2V, the charger stops charging.
July 28, 2008
FN6704.0