LTC3207EUF#PBF Linear Technology, LTC3207EUF#PBF Datasheet - Page 16

• Manufacturer Part Number: LTC3207EUF#PBF
• Description: IC LED DRIVR QVGA DISPLAY 24-QFN
• Manufacturer: Linear Technology
• Type: QVGA Display (I²C Interface)r

Specifications of LTC3207EUF#PBF

• Topology: Step-Up (Boost), Switched Capacitor (Charge Pump)
• Number Of Outputs: 13
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: RGB, White LED
• Frequency: *
• Voltage - Supply: 2.9 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 24-QFN
• Operating Temperature: -40°C ~ 85°C
• Internal Switch(s): Yes
• Efficiency: 91%
• Operating Supply Voltage (typ): 3.3/5V
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Package Type: QFN EP
• Pin Count: 24
• Mounting: Surface Mount
• Operating Supply Voltage (min): 2.9V
• Operating Supply Voltage (max): 5.5V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Current - Output / Channel: -
• Lead Free Status / Rohs Status: Compliant

LTC3207/LTC3207-1
APPLICATIONS INFORMATION
Flying Capacitor Selection
Warning: Polarized capacitors, such as tantalum or
aluminum, should never be used for the fl ying capaci-
tors since their voltage can reverse upon start-up of the
LTC3207/LTC3207-1. Ceramic capacitors should always
be used for the fl ying capacitors.
The fl ying capacitors control the strength of the charge
pump. In order to achieve the rated output current it is
necessary to have at least 1.6µF of capacitance for each
of the fl ying capacitors. Capacitors of different materials
lose their capacitance with higher temperature and voltage
at different rates. For example, a ceramic capacitor made
of X7R material will retain most of its capacitance from
–40°C to 85°C whereas a Z5U or Y5V style capacitor will
lose considerable capacitance over that range. Z5U and Y5V
capacitors may also have a very poor voltage coeffi cient
causing them to lose 60% or more of their capacitance when
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.
16
Table 1 shows a list of ceramic capacitor manufacturers
and how to contact them:
Table 1. Recommended Capacitor Vendors
Layout Considerations and Noise
The LTC3207/LTC3207-1 have been designed to minimize
EMI. However due to the high switching frequency and the
transient currents produced by the LTC3207/LTC3207-1,
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 5ns to 10ns edge-rate waveforms. The large
dv/dt on these pins can couple energy capacitively to
adjacent PCB runs. Magnetic fi elds can also be gen-
erated if the fl ying capacitors are not close to the
LTC3207/LTC3207-1 (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 LTC3207/LTC3207-1 pins. For a high quality
AC ground, it should be returned to a solid ground plane
that extends all the way to the LTC3207/LTC3207-1.
Taiyo Yuden
Murata
Vishay
Kemet
AVX
www.avxcorp.com
www.t-yuden.com
www.murata.com
www.vishay.com
www.kemet.com
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