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PDF LTC3621 Data sheet ( Hoja de datos )
| Número de pieza | LTC3621 | |
| Descripción | 1A Synchronous Step-Down Regulator | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LTC3621 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
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Fea ures
n Wide VIN Range: 2.7V to 17V
n Wide VOUT Range: 0.6V to VIN
n 95% Max Efficiency
n Low IQ < 3.5µA, Zero-Current Shutdown
n Constant Frequency (1MHz/2.25MHz)
n Full Dropout Operation with Low IQ
n 1A Rated Output Current
n ±1% Output Voltage Accuracy
n Current Mode Operation for Excellent Line and Load
Transient Response
n Pulse-Skipping, Forced Continuous, Burst Mode®
Operation
n Internal Compensation and Soft-Start
n Overtemperature Protection
n Compact 6-Lead DFN (2mm × 3mm) Package or
8-Lead MSOPE Package with Power Good Output
and Independent SGND Pin
pplica ions
n Portable-Handheld Scanners
n Automotive Applications
n Emergency Radio
LTC3621/LTC3621-2
17V, 1A Synchronous
Step-Down Regulator with
3.5µA Quiescent Current
Descrip ion
The LTC®3621/LTC3621-2 is a high efficiency 17V, 1A
synchronous monolithic step-down regulato.rThe switch-
ing frequency is fixed to 1MHz or 2.25MHz. The regulator
features ultralow quiescent current and high efficiencies
over a wide VOUT range.
The step-down regulator operates from an input voltage
range of 2.7V to 17V and provides an adjustable output
range from 0.6V to VIN while delivering up to 1A of output
current. A user-selectable mode input is provided to allow
the user to trade off ripple noise for light load efficiency;
Burst Mode operation provides the highest efficiency at
light loads, while pulse-skipping mode provides the low-
est voltage ripple.
List of LTC3621 Options
PART NAME
FREQUENCY
LTC3621
1.00MHz
LTC3621-2
2.25MHz
VOUT
Adjustable
Adjustable
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents, including 5481178, 6580258,
6498466, 6611131, 6177787, 5705919, 5847554.
Typical pplica ion
2.5V VOUT with 400mA Burst Clamp, fSW = 1MHz
VIN
2.7V TO 17V
10µF
VIN SW
LTC3621
RUN FB
MODE
INTVCC
GND
4.7µH
604k
191k
1µF
22pF
VOUT
2.5V
1A
22µF
3621 TA01a
Efficiency and Power Loss vs Load
100 1.0
90 EFFICIENCY
80
0.1
70
60
50 0.01
40
30
20
10
0
0.0001
POWER LOSS
0.001
0.001
0.01
VIN = 12V 0.0001
0.1 1
LOAD CURRENT (A)
3621 TA01b
For more information www.linear.com/LTC3621
3621f
1
http://www.Datasheet4U.com
1 page  
LTC3621/LTC3621-2
Typical er or ance harac eris ics TJ = 25°C, unless otherwise noted.
Efficiency vs Load at 1MHz
100
90
80
70
60
50
40
30
20
10
0 VIN = 12V
0.0001 0.001
0.01
VOUT = 2.5V
VOUT = 3.3V
VOUT = 5V
0.1 1
LOAD CURRENT (A)
3621 G16
Oscillator Frequency
vs Supply Voltage
2.50
2.45
2.40
2.35
2.30
2.25
2.20
2.15
2.10
2.05
2.00
2
7 12
SUPPLY VOLTAGE (V)
17
3621 G10
Reference Voltage
vs Temperature
600.5
600.0
599.5
599.0
598.5
598.0
597.5
–100
–50 0
50 100
TEMPERATURE (°C)
150
3521 G11
RDS(ON) vs Input Voltage
700
600
500
400 TOP FET
300
200 BOTTOM FET
100
0 2 4 6 8 10 12 14 16 18 20
INPUT VOLTAGE (V)
3621 G12
Line Regulation
0.5
0.3
0.1
–0.1
–0.3
–0.5
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
INPUT VOLTAGE (V)
3621 G15
RDS(ON) vs Temperature
600
550
500
TOP FET
450
400
350
300
250
200 BOTTOM FET
150
100
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3621 G13
vVsINTSemupppelryaCtuurrerent
6
5
4
SLEEP
3
2
1
0
–50 –25
SHUTDOWN
0 25 50 75
TEMPERATURE (°C)
100 125
3521 G17
For more information www.linear.com/LTC3621
Load Regulation
5 VIN = 12V
4 VOUT = 3.3V
3 FORCED CONTINUOUS MODE
2
1
0
–1
–2
–3
–4
–5
0
500 1000
LOAD CURRENT (mA)
1500
3621 G14
Switch Leakage
vs Temperature
0.09
0.08
0.07
0.06
BOTTOM FET
0.05
0.04
0.03
0.02
0.01
0
–50 –25
TOP FET
0 25 50 75
TEMPERATURE (°C)
100 125
3621 G18
3621f
5
5 Page 
LTC3621/LTC3621-2
pplica ions n or
Table 1. Inductor Selection Table
INDUCTOR
INDUCTANCE
(µH)
IHLP-1616BZ-11 Series
1.0
2.2
4.7
IHLP-2020BZ-01 Series
FDV0620 Series
1
2.2
3.3
4.7
5.6
6.8
1
2.2
3.3
4.7
MPLC0525L Series
1
1.5
2.2
HCP0703 Series
1
1.5
2.2
3.3
4.7
6.8
8.2
RLF7030 Series
WE-TPC 4828 Series
1
1.5
2.2
3.3
4.7
6.8
1.2
1.8
2.2
2.7
3.3
3.9
4.7
a ion
DCR
(mΩ)
24
61
95
18.9
45.6
79.2
108
113
139
18
37
51
68
16
24
40
9
14
18
28
37
54
64
8.8
9.6
12
20
31
45
17
20
23
27
30
47
52
MAX CURRENT
(A)
4.5
3.25
1.7
7
4.2
3.3
2.8
2.5
2.4
5.7
4
3.2
2.8
6.4
5.2
4.1
11
9
8
6
5.5
4.5
4
6.4
6.1
5.4
4.1
3.4
2.8
3.1
2.7
2.5
2.35
2.15
1.72
1.55
DIMENSIONS
(mm)
4.3 × 4.7
4.3 × 4.7
4.3 × 4.7
5.4 × 5.7
5.4 × 5.7
5.4 × 5.7
5.4 × 5.7
5.4 × 5.7
5.4 × 5.7
6.7 × 7.4
6.7 × 7.4
6.7 × 7.4
6.7 × 7.4
6.2 × 5.4
6.2 × 5.4
6.2 × 5.4
7 × 7.3
7 × 7.3
7 × 7.3
7 × 7.3
7 × 7.3
7 × 7.3
7 × 7.3
6.9 × 7.3
6.9 × 7.3
6.9 × 7.3
6.9 × 7.3
6.9 × 7.3
6.9 × 7.3
4.8 × 4.8
4.8 × 4.8
4.8 × 4.8
4.8 × 4.8
4.8 × 4.8
4.8 × 4.8
4.8 × 4.8
HEIGHT
(mm)
2
2
2
2
2
2
2
2
2
2
2
2
2
2.5
2.5
2.5
3
3
3
3
3
3
3
3.2
3.2
3.2
3.2
3.2
3.2
2.8
2.8
2.8
2.8
2.8
2.8
2.8
MANUFACTURER
Vishay
www.vishay.com
Toko
www.toko.com
NEC/Tokin
www.nec-tokin.com
Cooper Bussmann
www.cooperbussmann.com
TDK
www.tdk.com
Würth Elektronik
www.we-online.com
produce the most improvement. Percent efficiency can
be expressed as:
% Efficiency = 100% – (L1 + L2 + L3 +…)
where L1, L2, etc. are the individual losses as a percent-
age of input power. Although all dissipative elements in
the cir cuit produce losses, three main sour ces usually
account for most of the losses in LTC3621 circuits: 1) I2R
losses, 2) switching and biasing losses, 3) other losses.
1. I2R losses are calculated from the DC resistances of
the internal switches, R SW, and external inductor, RL.
In continuous mode, the average output current flows
through inductor L but is “chopped” between the
internal top and bottom power MOSFETs. Thus, the
series resistance looking into the SW pin is a function
of both top and bottom MOSFET RDS(ON) and the duty
cycle (DC) as follows:
RSW = (RDS(ON)TOP)(DC) + (RDS(ON)BOT)(1 – DC)
The RDS(ON) for both the top and bottom MOSFETs can be
obtained from the Typical Performance Characteristics
curves. Thus to obtain I2R losses:
I2R losses = IOUT2(RSW + RL)
For more information www.linear.com/LTC3621
3621f
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LTC3621.PDF ] | |
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