ltc3566 Linear Technology Corporation, ltc3566 Datasheet - Page 19

• Manufacturer Part Number: ltc3566
• Description: High Ef?ciency Usb Power Manager Plus 1a Buck-boost Converter
• Manufacturer: Linear Technology Corporation

APPLICATIONS INFORMATION
CLPROG Resistor and Capacitor
As described in the High Effi ciency Switching PowerPath
Controller section, the resistor on the CLPROG pin deter-
mines the average input current limit when the switching
regulator is set to either the 1x mode (USB 100mA), the
5x mode (USB 500mA) or the 10x mode. The input cur-
rent will be comprised of two components, the current
that is used to drive V
switching regulator. To ensure that the USB specifi cation
is strictly met, both components of input current should
be considered. The Electrical Characteristics table gives
values for quiescent currents in either setting as well as
current limit programming accuracy. To get as close to
the 500mA or 100mA specifi cations as possible, a 1%
resistor should be used. Recall that I
V
An averaging capacitor or an R-C combination is required
in parallel with the CLPROG resistor so that the switching
regulator can determine the average input current. This
network also provides the dominant pole for the feedback
loop when current limit is reached. To ensure stability, the
capacitor on CLPROG should be 0.1μF or larger.
CLPROG
/R
CLPROG
• (h
OUT
CLPROG
and the quiescent current of the
+ 1).
VBUS
= I
VBUSQ
+
Choosing the PowerPath Inductor
Because the input voltage range and output voltage range
of the power path switching regulator are both fairly nar-
row, the LTC3566 was designed for a specifi c inductance
value of 3.3μH. Some inductors which may be suitable
for this application are listed in Table 4.
Table 4. Recommended Inductors for PowerPath Controller
INDUCTOR
TYPE
LPS4018
D53LC
DB318C
WE-TPC
Type M1
CDRH6D12
CDRH6D38
(μH)
3.3
3.3
3.3
3.3
3.3
3.3
L
MAX
2.26
1.55
1.95
IDC
2.2
2.2
3.5
(A)
0.0625
0.034
0.070
0.065
0.020
MAX
DCR
0.08
(Ω)
3.9 × 3.9 × 1.7 CoilCraft
5.0 × 5.0 × 3.0
3.8 × 3.8 × 1.8
4.8 × 4.8 × 1.8 Würth Elektronik
6.7 × 6.7 × 1.5
7.0 × 7.0 × 4.0
SIZE IN mm
(L × W × H)
LTC3566
MANUFACTURER
www.coilcraft.
com
Toko
www.toko.com
www.we-online.
com
Sumida
www.sumida.com
19
3566p