DEMO C IR C U IT 1 4 6 0 A
DC1223A-B
Q U IC K S TA R T G U IDE
U L T R A L OW P OW ER 1 5 MA
H IG H EF F IC IEN C Y S T EP -DOW N C ON V ER T ER L T C 3 6 2 0 EDC
DESCRIPTION
Demonstration circuit 1460A is a high efficiency step-
dow n converter featuring the LTC3620EDC w ith internal
high side and synchronous pow er sw itches that draw s
onl 18µA of quiescent current. It has an internal fre-
y
quency cl
amp that forces a minimum sw itching fre-
quency at l
ight l
oads to minimize noise in the audio
range. I input vol
ts
t-age ranges betw een 2.9V and 5.5V.
I the input vol
f
tage fals bel 2.8V, an undervol
l
ow
tage
l
ockout circuit w il shut dow n the part. The demo circuit
l
Table 1. Performance Summary (TA = 25ºC)
provides sel
ectabl j
e umper outputs for 1.1V, 1.2V and
1.8V. The output can suppl up to 15mA of l cur-
y
oad
rent. G erber fil for this circuit are avail e. Cal the
es
abl
l
LTC Factory.
L
, LTC, LTM , LT, Burst M ode, O PTI O P, O ver-The-Top and Pol
-LO
yPhase are registered
trademarks of Linear Technol Corporation. Adaptive Pow er, C-Load, DirectSense, Easy
ogy
Drive, Fil
terCAD, H ot Sw ap, LinearView , µM odul M icropow er Sw itcherCAD, M ul
e,
timode
Dimming, N o Latency , N o Latency Del
ta-Sigma, N o R SEN SE, O perationalFil Panel
ter,
-
Protect, Pow erPath, Pow erSO T, SmartStart, SoftSpan, Stage Shedding, Sw itcherCAD,
ThinSO T, U l
traFast and VLDO are trademarks of Linear Technol Corporation. O ther
ogy
product names may be trademarks of the companies that manufacture the products.
PARAMETER
Input Voltage Range V
IN
Output Voltage V
OUT
Maximum Output Current
DC Quiescent Current
Minimum Switching Frequency (Internal)
CONDITION
V
IN
=3.6V
VALUE
2.9V to 5.5V
V
OUT
± 1.4% (LTC3620EDC Output adj. version)
V
OUT
± 1% (LTC3620-1EDC Fixed 1.1V version)
15mA
No switching, V
FB
=0.65V, SW
Pin Floating
V
FB
=0.65V, f
MIN
/MODE=0
18µA
50kHz
Q U ICK STA RT PROCEDU RE
The DC1460A is easy to set up to eval
uate the perform-
ance of the LTC3620EDC. For a proper measurement
equipment configuration, set up the circuit according to
the diagram in Figure 2.
N O TE.
W hen measuring the input or output vol
tage rippl care must be
e,
taken to avoid a l ground l on the osciloscope probe. M easure the
ong
ead
l
input or output vol
tage rippl by touching the probe tip di-rectl across the
e
y
VI or VO U T and G N D terminal See the M easurement Equipment Set-up
N
s.
diagram in Figure 1 for proper scope probe technique.
into JP2, JP3 or JP4 for vol
tages of 1.8V, 1.2V or
1.1V respectivel Set the l
y.
oad output current to
12ma.
3.
Appl 3.6V at VIN . M easure VO U T; it shoul read 0V.
y
d
I desired, one can measure the shutdow n suppl
f
y
current at this point. The suppl current w il be
y
l
about <1 µA in shutdow n. Set the l output current
oad
back to 0mA.
4.
Turn on VO U T by changing shunt XJP1 from the O FF
position to the O N position. The output vol
tage
shoul measure according to the vol
d
tage set by the
shunt j
umper in JP2.
5.
Set the l
oad output current to 5mA. Vary the input
vol
tage from 3.0V to 5.5V and VO U T shoul be
d
w ithin a tol
erance of ± 0.38% .
Pl
ease folow the procedure outl
l
ined bel for proper
ow
operation.
1.
Connect the input pow er suppl to the VIN and G N D
y
terminal Connect the l betw een the VO U T and
s.
oad
G N D terminal R efer to Figure 2 for the proper
s.
measurement equipment setup.
2.
Before proceeding to operation, insert j
umper shunt
XJP1 into the O FF position and insert a shunt j
umper
1
DC1460A
6.
Set the input vol
tage to 3.6V. Vary the VO U T l
oad
current from 1mA to 12mA, and the output vol
tage
shoul be w ithin a tol
d
erance of ± 0.5% (typical As
).
the l
oad is varied, there shoul not be any audibl
d
e
noise generated by the demo circuit.
Warning.
If the power for the demo board is carried in long leads,
the input voltage at the part could “ring”, which could affect the
operation of the circuit or even exceed the maximum voltage rating
of the IC. To eliminate the ringing, insert an electrolytic capacitor
(for instance, Panasonic part #
EEAFC1A220 (22µF/
10V)
on the pads
between the input power and return terminals on the bottom of the
demo board. The (greater) ESR of the electrolytic will dampen the
(possible) ringing voltage due to the use of long input leads. On a
normal, typical PCB, with short traces, the capacitor is not needed.
Fi
gure 1. M easuring Input or O ut Vol
put tage R i e
ppl
Fi
gure 2. Equi ent Set t Test LTC3620ED C
pm
up o
2
DC1460A
INDU CTOR COM PA RISON
Demonstration circuit 1460A comes w ith a standard
inductor (Coil
craft LPS3010-223M L) optimized for size
and efficiency. For handhel appl
d
ications requiring
minimal board area, this inductor can be repl
aced w ith
a smal surface mount 0603 package inductor, for ex-
l
ampl the Taiyo-Yuden CBM F1608T220K. Figure 3
e,
show s the inductor size comparison on the demonstra-
tion board w hil Figure 4 show s the efficiency perform-
e
ance of these tw o inductors.
Fi
gure 3. LTC3620ED C O perat ng w i D i erent Si I
i
th ff
ze nductors
Efficiency vs Iout, L=22uH
100
95
90
Efficiency (%)
85
80
75
70
65
60
1.00
Notes:
Vin = 3.6V
FMIN/Mode=0V
6
4
5
1 – Vout=2.5V LPS3010
2 – Vout=1.8V LPS3010
3 – Vout=1.2V LPS3010
4 – Vout=2.5V CBMF1608T
5 – Vout=1.8V CBMF1608T
6 – Vout=1.2V CBMF1608T
(CBMF1608T220K - 1.52mmx0.76mm Taiyo Yuden)
(LPS3010-223MLD - 2.95mmx 2.95mm Coil Craft)
1
2
3
10.00
Iout (mA)
cal f ciency vs. Load Current f D i f
or f erent I
nduct
ors
Fi
gure 4. Typi Ef i
100.00
3
DC1460A
Item Qty Reference
Part Description
REQUIRED CIRCUIT COMPONENTS
1
1
CFFW
Cap., NPO 22pF 25V 10%
2
2
COUT,CIN
Cap., X5R 1uF 6.3V 10%
3
1
CIN1
Cap., Tant. 10uF 16V 20%
4
1
L1
Inductor, 22uH
5
1
RFB1
Res., Chip 1.37M 0.06W 1%
6
1
RFB2
Res., Chip 681K 0.06W 1%
7
2
R1,R3
Res., Chip 1M 0.06W 5%
8
1
R2
Res., Chip 715K 0.06W 1%
9
1
U1
I.C., Volt. Reg.
ADDITIONAL DEMO BOARD CIRCUIT COMPONENTS
1
1
COUT1
Cap., X5R 0.1uF 25V 10%
HARDWARE FOR DEMO BOARD ONLY
1
7
E1,E2,E3,E4,E5,E6,E7 Turret, Testpoint
2
1
JP1
Headers, 3 Pins 2mm Ctrs.
3
3
JP2,JP3,JP4
Jumper, 2 Pins 2mm Ctrs.
4
1
JP5
Headers, Dbl. Row 2 x 3 2mm Ctrs.
5
1
RFB3
Res., Chip 1.37M 0.06W 1%
6
1
RFB4
Res., Chip 1.65M 0.06W 1%
7
3
XJP1,XJP2,XJP5
Shunt, 2mm Ctrs.
8
1
FAB, PRINTED CIRCUIT BOARD
9
1
STENCIL
Manufacturer / Part #
AVX 04023A220KAT2A
Taiyo Yuden JMK107BJ105KA-T
AVX TAJT106M016R
Coilcraft LPS3010-223
Vishay CRCW04021M37FKED
Vishay CRCW0402681KFKED
Vishay CRCW04021M00JNED
Vishay CRCW0402715KFKED
Linear Tech. Corp. LTC3620EDC
AVX 06033D104KAT2A
Mill Max 2501-2-00-80-00-00-07-0
Samtec TMM-103-02-L-S
Samtec TMM-102-02-L-S
Samtec TMM-103-02-L-D
Vishay CRCW04021M37FKED
Vishay CRCW04021M65FKED
Samtec 2SN-BK-G
DEMO CIRCUIT #1460A
STENCIL 1460A
5
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