ISL88731CEVAL2Z Intersil, ISL88731CEVAL2Z Datasheet - Page 23

• Manufacturer Part Number: ISL88731CEVAL2Z
• Description: ISL88731C EVALUATION BOARD 2 - 28 Ld TQFN - COMPLI
• Manufacturer: Intersil
• Series: -r

Specifications of ISL88731CEVAL2Z

• Main Purpose: Power Management, Battery Charger
• Embedded: No
• Utilized Ic / Part: ISL88731C
• Primary Attributes: Li-Ion / Li-Pol, SMBus interface
• Secondary Attributes: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

BOOT Pin
This pin’s di/dt is as high as the UGATE; therefore, this trace
should be as short as possible.
CSOP, CSON, CSSP and CSSN Pins
Accurate charge current and adapter current sensing is critical
for good performance. The current sense resistor connects to the
CSON and the CSOP pins through a low pass filter with the filter
capacitor very near the IC (see Figure 4). Traces from the sense
resistor should start at the pads of the sense resistor and should
be routed close together, through the low pass filter and to the
CSOP and CSON pins (see Figure 29). The CSON pin is also used
as the battery voltage feedback. The traces should be routed
away from the high dv/dt and di/dt pins like PHASE, BOOT pins.
In general, the current sense resistor should be close to the IC.
These guidelines should also be followed for the adapter current
sense resistor and CSSP and CSSN. Other layout arrangements
should be adjusted accordingly.
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C U R R E N T
T R A C E
H I G H
FIGURE 29. CURRENT SENSE RESISTOR LAYOUT
T O T H E L O W P A S S F I L T E R A N D
K E L V I N C O N N E C T I O N T R A C E S
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C S O P A N D C S O N
R E S I S T O R
S E N S E
23
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C U R R E N T
T R A C E
H I G H
ISL88731C
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DCIN Pin
This pin connects to AC-adapter output voltage, and should be
less noise sensitive.
Copper Size for the Phase Node
The capacitance of PHASE should be kept very low to minimize
ringing. It would be best to limit the size of the PHASE node
copper in strict accordance with the current and thermal
management of the application.
Identify the Power and Signal Ground
The input and output capacitors of the converters, the source
terminal of the bottom switching MOSFET PGND should connect
to the power ground. The other components should connect to
signal ground. Signal and power ground are tied together at one
point.
Clamping Capacitor for Switching MOSFET
It is recommended that ceramic capacitors be used closely
connected to the drain of the high-side MOSFET, and the source
of the low-side MOSFET. This capacitor reduces the noise and the
power loss of the MOSFET.
www.intersil.com
February 8, 2011
FN6978.2