LT1932ES6#TRM Linear Technology, LT1932ES6#TRM Datasheet - Page 5

• Manufacturer Part Number: LT1932ES6#TRM
• Description: IC LED DRIVR WHITE BCKLGT TSOT-6
• Manufacturer: Linear Technology
• Type: Backlight, White LEDr

Specifications of LT1932ES6#TRM

• Constant Current: Yes
• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: White LED
• Frequency: 800kHz ~ 1.6MHz
• Voltage - Supply: 1 V ~ 10 V
• Voltage - Output: 36V
• Mounting Type: Surface Mount
• Package / Case: TSOT-23-6, TSOT-6
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 40mA
• Internal Switch(s): Yes
• Efficiency: 80%
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: LT1932ES6#TRMTR

APPLICATIO S I FOR ATIO
Inductor Selection
Several inductors that work well with the LT1932 are listed
in Table 1. Many different sizes and shapes are available.
Consult each manufacturer for more detailed information
and for their entire selection of related parts. As core
losses at 1.2MHz are much lower for ferrite cores that for
the cheaper powdered-iron ones, ferrite core inductors
should be used to obtain the best efficiency. Choose an
inductor that can handle at least 0.5A and ensure that the
inductor has a low DCR (copper wire resistance) to mini-
mize I
a good choice for most LT1932 designs.
Table 1. Recommended Inductors
PART
ELJEA4R7
ELJEA6R8
LQH3C4R7M24
LQH3C100M24
LB2016B4R7
LB2016B100
CMD4D06-4R7
CMD4D06-6R8
CLQ4D10-4R7
CLQ4D10-6R8
Inductor Efficiency Considerations
Many applications have thickness requirements that re-
strict component heights to 1mm or 2mm. There are 2mm
tall inductors currently available that provide a low DCR
and low core losses that help provide good overall effi-
ciency. Inductors with a height of 1mm (and less) are
becoming more common, and a few companies have
introduced chip inductors that are not only thin, but have
a very small footprint as well. While these smaller induc-
tors will be a necessity in some designs, their smaller size
gives higher DCR and core losses, resulting in lower
efficiencies. Figure 2 shows efficiency for the Typical
Application circuit on the front page of this data sheet, with
several different inductors. The larger devices improve
2
R power losses. A 4.7 H or 6.8 H inductor will be
( H)
4.7
6.8
4.7
4.7
6.8
4.7
6.8
4.7
6.8
10
L
U
(m )
MAX
DCR
180
250
260
300
250
350
216
296
162
195
U
HEIGHT
(mm)
MAX
2.2
2.2
2.2
2.2
1.6
1.6
0.8
0.8
1.2
1.2
W
VENDOR
Panasonic
[phone]
www.panasonic.com
Murata
[phone]
www.murata.com
Taiyo Yuden
[phone]
www.t-yuden.com
Sumida
[phone]
www.sumida.com
U
efficiency by up to 12% over the smaller, thinner ones.
Keep this in mind when choosing an inductor.
The value of inductance also plays an important role in the
overall system efficiency. While a 1 H inductor will have
a lower DCR and a higher current rating than the 6.8 H
version of the same part, lower inductance will result in
higher peak currents in the switch, inductor and diode.
Efficiency will suffer if inductance is too small. Figure 3
shows the efficiency of the Typical Application on the front
page of this data sheet, with several different values of the
same type of inductor (Panasonic ELJEA). The smaller
values give an efficiency 3% to 5% lower than the 6.8 H
value.
Figure 3. Efficiency for Several Different Inductor Values
Figure 2. Efficiency for Several Different Inductor Types
85
80
75
70
65
60
55
85
80
75
70
65
60
55
0
0
TAIYO YUDEN
LB2016B6R8
CLQ4D10-6R8
4.7 H
22 H
SUMIDA
5
5
LED CURRENT (mA)
LED CURRENT (mA)
TAIYO YUDEN
LB2012B6R8
6.8 H
10
10
2.2 H
PANASONIC
V
4 WHITE LEDs
PANASONIC ELJEA
INDUCTORS
ELJEA6R8
IN
CMD4D06-6R8
= 3.6V
V
4 WHITE LEDs
ALL ARE 10 H
INDUCTORS
IN
SUMIDA
15
15
= 3.6V
1932 F02
1932 F03
20
20
LT1932
5
1932f