DC1460A - Demo Manual

DEMO C IR C U IT 1 4 6 0 A
Q U IC K S TADC1223A-B
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 stepdow n converter featuring the LTC3620EDC w ith internal
high side and synchronous pow er sw itches that draw s
only 18µA of quiescent current. It has an internal frequency clamp that forces a minimum sw itching frequency at light loads to minimize noise in the audio
range. Its input volt-age ranges betw een 2.9V and 5.5V.
If the input voltage falls below 2.8V, an undervoltage
lockout circuit w illshut dow n the part. The demo circuit
provides selectable jumper outputs for 1.1V, 1.2V and
1.8V. The output can supply up to 15mA of load current. G erber files for this circuit are available. Call the
LTC Factory.
L, LTC, LTM , LT, Burst M ode, O PTI-LO O P, O ver-The-Top and PolyPhase are registered
trademarks of Linear Technology Corporation. Adaptive Pow er, C-Load, DirectSense, Easy
Drive, FilterCAD, H ot Sw ap, LinearView , µM odule, M icropow er Sw itcherCAD, M ultimode
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ThinSO T, U ltraFast and VLDO are trademarks of Linear Technology Corporation. O ther
product names may be trademarks of the companies that manufacture the products.
Table 1. Performance Summary (TA = 25ºC)
PARAMETER
CONDITION
VALUE
Input Voltage Range VIN
Output Voltage VOUT
2.9V to 5.5V
VIN=3.6V
VOUT ± 1.4% (LTC3620EDC Output adj. version)
VOUT ± 1% (LTC3620-1EDC Fixed 1.1V version)
Maximum Output Current
DC Quiescent Current
15mA
No switching, VFB=0.65V, SW
18µA
Pin Floating
Minimum Switching Frequency (Internal)
VFB=0.65V, fMIN/MODE=0
50kHz
Q U ICK STA RT PROCEDU RE
The DC1460A is easy to set up to evaluate the performance 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 voltage ripple, care must be
taken to avoid a long ground lead on the oscilloscope probe. M easure the
input or output voltage ripple by touching the probe tip di-rectly across the
VIN or VO U T and G N D terminals. See the M easurement Equipment Set-up
diagram in Figure 1 for proper scope probe technique.
Please follow the procedure outlined below for proper
operation.
1. Connect the input pow er supply to the VIN and G N D
terminals. Connect the load betw een the VO U T and
G N D terminals. R efer to Figure 2 for the proper
measurement equipment setup.
2. Before proceeding to operation, insert jumper shunt
XJP1 into the O FF position and insert a shunt jumper
into JP2, JP3 or JP4 for voltages of 1.8V, 1.2V or
1.1V respectively. Set the load output current to
12ma.
3. Apply 3.6V at VIN . M easure VO U T; it should read 0V.
If desired, one can measure the shutdow n supply
current at this point. The supply current w ill be
about <1 µA in shutdow n. Set the load output current
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 voltage
should measure according to the voltage set by the
shunt jumper in JP2.
5. Set the load output current to 5mA. Vary the input
voltage from 3.0V to 5.5V and VO U T should be
w ithin a tolerance of ± 0.38% .
1
DC1460A
6. Set the input voltage to 3.6V. Vary the VO U T load
current from 1mA to 12mA, and the output voltage
should be w ithin a tolerance of ± 0.5% (typical). As
the load is varied, there should not be any audible
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.
Figure 1. M easuring Input or O utput Voltage R ipple
Figure 2. Equipm ent Setup to Test LTC3620ED C
2
DC1460A
INDU CTOR COM PA RISON
Demonstration circuit 1460A comes w ith a standard
inductor (Coilcraft LPS3010-223M L) optimized for size
and efficiency. For handheld applications requiring
minimal board area, this inductor can be replaced w ith
a small surface mount 0603 package inductor, for ex-
ample, the Taiyo-Yuden CBM F1608T220K. Figure 3
show s the inductor size comparison on the demonstration board w hile Figure 4 show s the efficiency performance of these tw o inductors.
Figure 3. LTC3620ED C O perating w ith D ifferent Size Inductors
Efficiency vs Iout, L=22uH
100
(CBMF1608T220K - 1.52mmx0.76mm Taiyo Yuden)
(LPS3010-223MLD - 2.95mmx 2.95mm Coil Craft)
1
95
2
Efficiency (%)
90
3
4
85
6
80
75
70
65
60
1.00
Notes:
Vin = 3.6V
FMIN/Mode=0V
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
10.00
100.00
Iout (mA)
Figure 4. Typical Efficiency vs. Load Current for D ifferent Inductors
3
DC1460A
4
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.
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
ADDITIONAL DEMO BOARD CIRCUIT COMPONENTS
1
1
COUT1
Cap., X5R 0.1uF 25V 10%
AVX 06033D104KAT2A
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
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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