PM6600 STMicroelectronics, PM6600 Datasheet - Page 45

• Manufacturer Part Number: PM6600
• Description: IC LED DRIVR WHT BCKLT 24-VFQFPN
• Manufacturer: STMicroelectronics
• Type: Backlight, White LEDr

Specifications of PM6600

• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 6
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: White LED
• Frequency: 200kHz ~ 1MHz
• Voltage - Supply: 4.7 V ~ 28 V
• Voltage - Output: 36V
• Mounting Type: Surface Mount
• Package / Case: 24-VFQFN, 24-VFQFPN
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 32mA
• Internal Switch(s): Yes
• Number Of Segments: 60
• Operating Supply Voltage: 4.7 V to 28 V
• Maximum Power Dissipation: 2.3 W
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• For Use With: 497-8414 - BOARD EVAL BASED ON PM6600
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Efficiency: -
• Lead Free Status / Rohs Status: Details

PM6600
A.3
A.4
A.5
A.6
Take care not to design the LX switching copper area near the COMP network, in order to
avoid cross-talking between the power switching signal and the compensation one.
A very important thing is to keep the feedbacks (ROWs) and compensation traces as short
as possible to minimize noise pick up and to keep them away from noise or field sources
(the switch, diode, inductor). The feedbacks and compensation traces should never pass
under the inductor, switch or diode (even if on opposite sides of the PCB). They should not
run close to and parallel to a noisy (power critical) trace.
LX area – vout power area
The LX Switching node area should be properly dimensioned ‡ large and short enough to
assure a noise-free working. The power loop of LX, inductor, PGND must be as short as
possible, by mounting L, D, Cout as close as possible one each other. The power area
should be positioned away from the critical signals (mainly the compensation network).
The L, D, Cout components are in the power critical path.
The Cin position is less important than the L, D, Cout. However, it is preferable to have all
the power components in the same side of the device, to reduce the power path length and
to avoid noise coupling between power and signal traces.
Overvoltage divider
Since the PM6600 works with a compensated divider connected to the OVSEL pin to set the
Overvoltage threshold, the two capacitors should be mounted as close as possible to the
OVSEL pin of the device.
Then you can choose the resistors position near of them.
In the standard PM6600 demonstration board, the capacitors and resistors position is
swapped. This was done because of the need to test the application in different working
conditions.
The capacitors have the priority in the positioning because they clean the OVSEL signal of
the noise caused by the LX switching node.
LDO5 – AVCC filter
The 2 capacitors should be mounted as close as possible to the LDO5 and VCC pins of the
device. The resistor has to be mounted near of them or it can be omitted (short) where the
PCB dimensions are very small.
ROWs current generators
The ROWs current generators are referred to SGND. In order to assure the best
performances for current accuracy/mismatch the PCB traces lengths from the ROWs pins to
the LEDs should be the same for all the current generators.
Doc ID 14248 Rev 7
Layout guidelines
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