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PDF ADP1621 Data sheet ( Hoja de datos )
| Número de pieza | ADP1621 | |
| Descripción | Current-Mode Step-Up DC/DC Controller | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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Constant-Frequency, Current-Mode
Step-Up DC/DC Controller
ADP1621
FEATURES
92% efficiency (no sense resistor required)
±1.0% initial accuracy
IC supply voltage range: 2.9 V to 5.5 V
Power-input voltage as low as 1.0 V
Capable of high supply input voltage (>5.5 V)
with an external NPN or a resistor
VIN UVLO and 35 mA shunt regulator
External slope compensation with 1 resistor
Programmable operating frequency
(100 kHz to 1.5 MHz) with 1 resistor
Lossless current sensing for switch-node voltage <30 V
Resistor current sensing for switch-node voltage >30 V
Synchronizable to external clock
Current-mode operation for excellent line and load transient
responses
10 μA shutdown current
Current limit and thermal overload protection
Soft start in 2048 clock cycles
APPLICATIONS
APD bias
Portable electronic equipment
Isolated dc/dc converter
Step-up/step-down dc/dc converter
LED driver for laptop computer and navigation system
LCD backlighting
GENERAL DESCRIPTION
The ADP1621 is a fixed-frequency, pulse-width modulation
(PWM), current-mode, step-up converter controller. It drives an
external n-channel MOSFET to convert the input voltage to a
higher output voltage. The ADP1621 can also be used to drive
flyback, SEPIC, and forward converter topologies, either isolated
or nonisolated.
The ADP1621 eliminates the use of a current-sense power
resistor by measuring the voltage drop across the on resistance
of the n-channel MOSFET. This technique, allowed up to a
maximum voltage of 30 V at the switch node, maximizes
efficiency and reduces cost. For switch-node voltages higher than
30 V or for more accurate current limiting, the CS pin can be
connected to a current-sense resistor in the source of the MOSFET.
The slope compensation is implemented by an external resistor,
allowing a wide range of external components (inductors and
MOSFETs), and can be chosen for various switching frequencies
and input and output voltages.
The ADP1621 supply input voltage range is 2.9 V to 5.5 V, although
higher input voltages are possible with the use of a small-signal
Rev. A
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
TYPICAL APPLICATION CIRCUIT
VIN = 3.3V
L1
4.7µH
D1
C3 C4
1µF 0.1µF
10V 10V
PIN IN
RS
80Ω
CS
R1
35.7kΩ
1%
ADP1621
SDSN
GATE
R2
11.5kΩ
M1 1%
COMP
PGND
C2
120pF
RCOMP
9.09kΩ
CCOMP
1.8nF
FREQ
FB
GND
RFREQ
31.6kΩ
1%
VOUT = 5V
1A
COUT1
1µF
10V
COUT2
10µF
10V
COUT3
150µF
6.3V
×2
C1
47µF
6.3V
AGND
fOSC = 600kHz
C1 = MURATA GRM31CR60J476M
COUT3 = SANYO POSCAP 6TPE150M
L1 = TOKO FDV0630-4R7M
M1 = VISHAY Si7882DP
D1 = VISHAY SSA33L
Figure 1. High Efficiency Output Boost Converter in Lossless Mode,
3.3 V Input, 5 V Output (Bootstrapped)
100
90
80
70
60
50
40
30
0.01
0.1
1
LOAD CURRENT (A)
Figure 2. Efficiency of Circuit Shown in Figure 1
10
NPN pass transistor or a single resistor. The voltage of the
power input can be as low as 1 V for fuel cell applications. The
switching frequency is set by an external resistor over a range of
100 kHz to 1.5 MHz and can be synchronized to an external
clock by using the SDSN pin. The shutdown quiescent current is
less than 10 μA. The ADP1621 has a thermal shutdown feature
that shuts down the gate driver when the junction temperature
reaches approximately 150°C. The internal soft start circuit limits
inrush current at startup. The ADP1621 is available in the 10-lead
MSOP lead-free package and is specified over the −40°C to +125°C
junction temperature range.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2006 Analog Devices, Inc. All rights reserved.
1 page  
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Rating
IN to GND
FB, COMP, SDSN, FREQ, GATE to GND
CS to GND
−0.3 V to VSHUNT
−0.3 V to (VIN + 0.3 V)
−5 V to +33 V
PIN to PGND
Supply Current into IN
−0.3 V to VSHUNT
25 mA
Supply Current into PIN
35 mA
Storage Temperature Range
−55°C to +150°C
Junction Operating Temperature Range1 −55°C to +150°C
Junction Storage Temperature Range
−55°C to +150°C
Lead Temperature (Soldering, 10 sec)
300°C
Package Power Dissipation1
(TJ,MAX − TA)/θJA
1In applications where high power dissipation and poor package thermal
resistance are present, the maximum ambient temperature may need to be
derated. Maximum ambient temperature (TA,MAX) is dependent on the
maximum operating junction temperature (TJ,MAX = 150oC), the maximum
power dissipation of the device in the application (PD,MAX), and the junction-
to-ambient thermal resistance of the package in the application (θJA), is given
by the following equation: TA,MAX = TJ,MAX -- (θJA x PD,MAX).
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ADP1621
Absolute maximum ratings apply individually only, not in
combination. Unless otherwise specified, all other voltages are
referenced to GND.
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 3. Thermal Resistance
Package Type
10-lead MSOP on a 2-layer PCB
10-lead MSOP on a 4-layer PCB
θJA Unit
200 °C/W
172 °C/W
Junction-to-ambient thermal resistance of the package is based
on modeling and calculation using 2-layer and 4-layer boards,
and natural convection. The junction-to-ambient thermal
resistance is application- and board-layout dependent. In
applications where high maximum power dissipation exists,
attention to thermal dissipation issues in board design is
required.
ESD CAUTION
Rev. A | Page 5 of 32
5 Page 
TA = 25°C LOAD = 0.3A
VIN = 3.3V CCM OPERATION
VOUT = 5V
4
CH4 = INDUCTOR CURRENT
2
CH2 = DRAIN VOLTAGE
1
CH1 = GATE
CH1 5V
CH2 5V
M2µs
CH4 500mAΩ
A CH1
Figure 23. CCM Switching Waveform
2.9V
TA = 25°C
VIN = 3.3V
fVSOWUT=
= 5V
220kHz
SOFT-START = 9.3ms
CH1 = VOUT
2
1
3
CH1 1V
CH3 5V
CH2 = SDSN
CH2 5V
M2ms
CH3 = GATE
A CH1 4.5V
Figure 24. Soft Start Waveform
ADP1621
LOAD CURRENT
FROM 0.2A TO 1.2A
4
1
OUTPUT, AC-COUPLED
TA = 25°C
VIN = 3.3V
VOUT = 5V
CH1 50mV
CH4 1AΩ
M200µs
A CH4 700V
Figure 26. Load Transient Response of the Circuit Shown in Figure 1
TA = 25°C
VOUT = 5V
NO LOAD AT VOUT
CH1 = VOUT, AC-COUPLED
1
CH2 = VIN FROM 3V TO 4V
2
CH1 50mV CH2 2V
M400µs
A CH2 3.8V
Figure 27. Line Transient Response of the Configuration Shown in Figure 1
with No Load
TA = 25°C
VOUT = 5V
LOAD AT VOUT = 1A
1
CH1 = VOUT, AC-COUPLED
CH2 = VIN FROM 3V TO 4V
2
CH1 50mV CH2 2V
M400µs
A CH2 3.8V
Figure 25. Line Transient Response of the Configuration Shown in Figure 1
with a 1 A Load
Rev. A | Page 11 of 32
11 Page | ||
| Páginas | Total 32 Páginas | |
| PDF Descargar | [ Datasheet ADP1621.PDF ] | |
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