PM6600 STMicroelectronics, PM6600 Datasheet - Page 56

• 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

Application suggestions
C.2
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EN, DIM path in production line
Normally, in production line, the LCD modules are connected to testing machines with long
wires. The VIN, EN and DIM signals are provided with automatic testing equipment, such as
relays and/or software controlled switches, that connects the dedicated power supplies to
the board.
The wires parasitic inductance can lead to voltage spikes conditions that can exceed the
device maximum absolute ratings, thus resulting in a device damage.
In order to filter the critical signals, the suggestion is to add an RC network between the
board connector and the device pin.
Figure 59. EN pin filter
In case of the EN pin, the recommended power supply value is 3.3 V, and we also suggest
to use an RC low pass filter network with Ren1 = 3.3 kΩ, Cen = 470 nF.
If the EN is not externally driven, the PM6600 has an internal pull-up that permits to turn the
device ON by leaving the EN pin floating. In case the external driving circuit is present, but it
is not guaranteed that it drives the EN pin to a logic “0”, an external pull-down resistor Ren2
is needed.
Figure 60. DIM pin filter
In the production line, the DIM signal is provided by a common power supply/signal
generator to a set of LED driver boards under test. The use of long wires and relays can
provoke spikes on the DIM pin, with a voltage level higher than the absolute maximum
ratings of the device. In this case, the device is internally damaged and stops working
properly.
To protect the DIM pin of the PM6600 device, a resistor Rdim1 is needed. It prevents a large
inrush current flowing into the device in case the voltage spike is exceeding the absolute
maximum ratings.
In case the DIM signal is provided by a micro controller (in production line and/or in the final
application), a pull-down resistor Rdim2 can be needed. If the micro controller is not
powered, it is possible that the voltage on the DIM pin of the PM6600 device will go to a logic
high level, because of board noise or signals coupling. The pull-down resistor avoids this
issue.
EN
D IM
Doc ID 14248 Rev 7
100 kR
1
R en 2
2
1kR to 3. 3kR
R dim 1
3 .3k R
R en1
470 nF
C en
R dim 2
10 0kR
D IM
EN
PM6600