isl9203crz-t Intersil Corporation, isl9203crz-t Datasheet - Page 14

• Manufacturer Part Number: isl9203crz-t
• Description: Li-ion/li Polymer Battery Charger
• Manufacturer: Intersil Corporation

NOTE: Both outputs are pulled up with external resistors.
FAULT and STATUS Pull-Up Resistors
Both FAULT and STATUS pins are open-drain outputs that
need an external pull-up resistor. It is recommended that
both pins be pulled up to the input voltage or the 2.8V from
the V2P8 pin. If the indication pins have to be pulled up to
other voltages, the user needs to examine carefully whether
or not the ESD diodes will form a leakage current path to the
battery when the input power is removed. If the leakage path
does exist, an external transistor is required to break the
path.
Figure 24 shows the implementation. If the FAULT pin is
directly pulled up to the VCC voltage (not shown in Figure
24), a current will flow from the VCC to the FAULT pin, then
through the ESD diode to the VIN pin. Any leakage on the
VIN pin, caused by an external or internal current path, will
result in a current path from VCC to ground.
The N-channel MOSFET Q
gate of Q
FAULT pin outputs a logic low signal, Q
drain outputs a low signal as well. When FAULT is high
impedance, R
power is removed, the Q
the Q
High
High
Low
FAULT STATUS
FIGURE 23. THE V2P8 PIN OUTPUT vs THE INPUT VOLTAGE
1
drain stays high.
High
Low
High
1
V
V2P8
is connected to VIN or the V2P8 pin. When the
IN
1
AT THE VIN PIN. VERTICAL: 1V/DIV,
HORIZONTAL: 100ms/DIV
TABLE 4. STATUS INDICATIONS
pulls the Q
3.4V
2.8V
Charge completed with no fault (Inhibit) or
Standby
Charging in one of the three modes
Fault
1
gate voltage is also removed, thus
1
1
drain to high. When the input
14
buffers the FAULT pin. The
INDICATION
1
is turned on and its
2.4V
ISL9203
Shutdown
The ISL9203 can be shutdown by pulling the EN pin to
ground. When shut down, the charger draws typically less
than 30PA current from the input power and the 2.8V output
at the V2P8 pin is also turned off. The EN pin needs be
driven with an open-drain or open-collector logic output, so
that the EN pin is floating when the charger is enabled. If the
EN pin is driven by an external source, the POR threshold
voltage will be affected.
Input and Output Capacitor Selection
Typically any type of capacitors can be used for the input
and the output. Use of a 0.47PF or higher value ceramic
capacitor for the input is recommended. When the battery is
attached to the charger, the output capacitor can be any
ceramic type with the value higher than 0.1PF. However, if
there is a chance the charger will be used as an LDO linear
regulator, a 10PF tantalum capacitor is recommended. Note
that the charger always steps through the 15-cycle V
verification time before the charge current rises to the
constant charge current, as discussed earlier. Hence, when
using as an LDO, the system should make sure not to load
the charger heavily until the 15-cycle verification is
completed.
Working with Current-Limited Adapter
The ISL9203 can work with a current-limited adapter to
significantly reduce the thermal dissipation during charging.
Refer to the ISL6292 data sheet, which can be found at
http://www.intersil.com, for more details.
Board Layout Recommendations
The ISL9203 internal thermal foldback function limits the
charge current when the internal temperature reaches
approximately 100°C. In order to maximize the current
capability, it is very important that the exposed pad under the
VIN
GND
FIGURE 24. PULL-UP CIRCUIT TO AVOID BATTERY LEAKAGE
EN
Note:
R
approximately 140k: when the EN is grounded.
LKG
R
LKG
is approximately 240k: when EN is floating and is
CURRENT IN THE ESD DIODES.
ESD Diode
VIN
STATUS
FAULT
VIN or
V2P8
February 3, 2005
VCC
MIN
FN6106.0
Q
R
1
1