ISL9220IRTZ-T7A Intersil, ISL9220IRTZ-T7A Datasheet - Page 11

• Manufacturer Part Number: ISL9220IRTZ-T7A
• Description: IC BATT CHRGR LIION 1CELL 20TQFN
• Manufacturer: Intersil

Specifications of ISL9220IRTZ-T7A

• Function: Charge Management
• Battery Chemistry: Lithium-Ion (Li-Ion), Lithium-Polymer (Li-Pol)
• Voltage - Supply: 4.5 V ~ 14 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-WFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

STAT1 and STAT2 are configured to indicate various
charging conditions as given in Table 1.
A fault status is triggered under one of these conditions:
To exit the fault mode, the input power has to be
recycled, or the EN pin is toggled to HI and back to LO.
Applications Information
Power-On Reset (POR)
The ISL9220, ISL9220A resets itself as the input voltage
rises above the POR rising threshold. The internal
oscillator starts to oscillate, the internal timer is reset,
and the charger begins to charge the battery. The
STAT1/2 pins will indicate the operating condition
according to Table 1.
Trickle Charge
If the battery voltage is below the trickle charge
threshold, the ISL9220, ISL9220A delivers a small
current to charge the battery until the battery voltage
reaches the fast charge threshold value. There are two
trickle charge thresholds. The first threshold, V
to pre-charge a deeply discharged battery or short
circuit. The second threshold, V
discharged to a voltage range from 2.5V to 3V. When
V
as a linear regulator, providing a 50mA constant current
to output. When V
ISL9220A starts to operate as a switching charger. The
trickle charge current is programmable by RISET2.
Charge Cycle
A charge cycle consists of three charge modes: trickle
mode, constant current (CC) mode, and constant voltage
(CV) mode. The charge cycle always starts with the
trickle mode until the battery voltage stays above V
(3.0V typical). If the battery voltage stays below V
the charger stays in the trickle mode. The charger
operates in CC mode after the battery voltage is above
V
final charge voltage, the CV mode operation begins.
Since the battery terminal voltage is regulated at the
constant output voltage in the CV mode, the charge
current begins to drop. After the charge current drops
below the end-of-charge level, which is programmed by
RISET2. The ISL9220, ISL9220A indicates the
end-of-charge (EOC) with STAT1 and STAT2 and
terminates the charge. The following events initiate a
new charge cycle:
• POR
• A new battery being inserted (detected by RTH pin)
• Recovery from an battery over-temperature fault
• The EN pin is toggled from HI-to-LO
1. V
2. Timeout occurs before the EOC current has been
BAT
MIN
reached
BAT
. As the battery-pack terminal voltage rises to the
is below V
> VOUT_OVP threshold
PCHG1,
BAT
reaches V
the ISL9220, ISL9220A operates
11
PCHG2
PCHG2,
is for batteries
the ISL9220,
ISL9220, ISL9220A
PCHG1
MIN
MIN
, is
,
Recharge
After a charge cycle completes at a timeout event,
charging is prohibited until the recharge condition
(V
the timer reset to zero.
Inductor and Output Capacitor Selection
To achieve better steady state and transient response,
ISL9220, ISL9220A typically uses a 10μH inductor. The
peak-to-peak inductor current ripple can be expressed in
Equation 9:
In Equation 9, usually the typical values can be used but
to have a more conservative estimation, the inductance
should consider the value with worst case tolerance; and
for switching frequency f
“Electrical Specifications” table on page 3 can be used. A
worst case for charge current ripple is when battery
voltage is half of the input voltage.
To select the inductor, its saturation current rating should
be at least higher than the sum of the maximum output
current and half of the delta calculated from Equation 9.
Another more conservative approach is to select the
inductor with the current rating higher than the peak
current limit.
Another consideration is the inductor DC resistance since
it directly affects the efficiency of the converter. Ideally,
the inductor with the lower DC resistance should be
considered to achieve higher efficiency.
Inductor specifications could be different from different
manufacturers so please check with each manufacturer if
additional information is needed.
For the output capacitor, a ceramic capacitor can be used
because of the low ESR values, which helps to minimize
the output voltage ripple. A typical value of 10μF/10V
ceramic capacitor should be enough for most of the
applications and the capacitor should be X5R or X7R.
Board Layout Recommendations
The ISL9220, ISL9220A is a high frequency switching
charger and hence the PCB layout is a very important
design practice to ensure a satisfactory performance.
The power loop is composed of the output inductor L, the
output capacitor C
is important to make the power loop as small as possible
and the connecting traces among them should be direct,
short and wide; the same practice should be applied to
the connection of the VIN pin, the input capacitor C
and PGND.
The switching node of the converter, the SW pin, and the
traces connected to this node are very noisy, so keep the
voltage feedback trace and other noise sensitive traces
away from these noisy traces.
ΔI
BAT
=
V
-------------------------------------------------- -
BAT
< VRECHG) is met, then the charging restarts with
•
L f
⎛
⎜
⎝
•
1
–
S
V
-------------- -
V
BAT
IN
OUT
⎞
⎟
⎠
, the SW pin and the PGND pin. It
S
, the minimum f
S
from the
February 8, 2011
FN6936.2
(EQ. 9)
IN