LTC3208EUH#PBF Linear Technology, LTC3208EUH#PBF Datasheet - Page 18

• Manufacturer Part Number: LTC3208EUH#PBF
• Description: IC LED DRIVR QVGA DISPLAY 32-QFN
• Manufacturer: Linear Technology
• Type: QVGA Display (I²C Interface)r

Specifications of LTC3208EUH#PBF

• Topology: Step-Up (Boost), Switched Capacitor (Charge Pump)
• Number Of Outputs: 17
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: RGB, White LED
• Frequency: 600kHz ~ 1.2MHz
• Voltage - Supply: 2.9 V ~ 4.5 V
• Mounting Type: Surface Mount
• Package / Case: 32-QFN
• Operating Temperature: -40°C ~ 85°C
• Internal Switch(s): Yes
• Efficiency: 95%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Current - Output / Channel: -

APPLICATIO S I FOR ATIO
LTC3208
18
the rated voltage is applied. Therefore, when comparing
different capacitors, it is often more appropriate to compare
the amount of achievable capacitance for a given case size
rather than comparing the specifi ed capacitance value. For
example, overrated voltage and temperature conditions, a
1µF, 10V, Y5V ceramic capacitor in a 0603 case may not
provide any more capacitance than a 0.22µF, 10V, X7R
available in the same case. The capacitor manufacturer’s
data sheet should be consulted to determine what value
of capacitor is needed to ensure minimum capacitances
at all temperatures and voltages.
Table 1 shows a list of ceramic capacitor manufacturers
and how to contact them:
Table 1. Recommended Capacitor Vendors
AVX
Kemet
Murata
Taiyo Yuden
Vishay
Layout Considerations and Noise
Due to its high switching frequency and the transient
currents produced by the LTC3208, careful board layout
is necessary. A true ground plane and short connections
to all capacitors will improve performance and ensure
proper regulation under all conditions.
The fl ying capacitor pins C1P, C2P, C1M and C2M will have
very high edge rate waveforms. The large dv/dt on these
pins can couple energy capacitively to adjacent PCB runs.
Magnetic fi elds can also be generated if the fl ying capacitors
are not close to the LTC3208 (i.e., the loop area is large).
To decouple capacitive energy transfer, a Faraday shield
may be used. This is a grounded PCB trace between the
sensitive node and the LTC3208 pins. For a high quality
AC ground, it should be returned to a solid ground plane
that extends all the way to the LTC3208.
U
U
www.avxcorp.com
www.kemet.com
www.murata.com
www.t-yuden.com
www.vishay.com
W
U
The following guidelines should be followed when design-
ing a PCB layout for the LTC3208.
• The exposed pad should be soldered to a large copper
• Input and output capacitors (C1 and C4) must be placed
• The fl ying capacitors (C2 and C3) must be placed close
• V
• LED pads must be large and connected to other layers
GND PLANE
GND
LAYER
plane that is connected to a solid, low impedance ground
plane using plated, through-hole vias for proper heat
sinking and noise protection.
close to the part.
to the part. The traces running from the pins to the
capacitor pads should be as wide as possible.
inductance and handle the high currents.
of metal to ensure proper heat sinking.
BAT
V
, CPO traces must be made wide to minimize
BAT
LAYER
CPO
PLANE
C4
Figure 7. PC Board Layout Example
GND
1
V
BAT
GND
CONNECT TO
GND PLANE LAYER
V
BAT
C5
GND
C2
R1
GND
C3
ALL VIAS LABELED GND
ARE CONNECTED TO
GND PLANE LAYER
R
REF
C6
C1
GND
ALL VIAS LABELED
ARE CONNECTED TO
V
DV
BAT
GND
V
CC
BAT
PLANE LAYER
LAYER
V
BAT
PLANE
GND PLANE
LAYER
V
3208fa
BAT
3208 F07