DC/DC Controller. ADP1621 Datasheet

ADP1621 Controller. Datasheet pdf. Equivalent


Analog Devices ADP1621
www.DataSheet4U.com
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
80
CS
R1
35.7k
1%
ADP1621
SDSN
GATE
R2
11.5k
M1 1%
COMP
PGND
C2
120pF
RCOMP
9.09k
CCOMP
1.8nF
FREQ
FB
GND
RFREQ
31.6k
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.


ADP1621 Datasheet
Recommendation ADP1621 Datasheet
Part ADP1621
Description Current-Mode Step-Up DC/DC Controller
Feature ADP1621; www.DataSheet4U.com Constant-Frequency, Current-Mode Step-Up DC/DC Controller ADP1621 FEATURES 92% .
Manufacture Analog Devices
Datasheet
Download ADP1621 Datasheet




Analog Devices ADP1621
ADP1621
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
General Description ......................................................................... 1
Typical Application Circuit ............................................................. 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 5
Thermal Resistance ...................................................................... 5
ESD Caution.................................................................................. 5
Simplified Block Diagram ............................................................... 6
Pin Configuration and Function Descriptions............................. 7
Typical Performance Characteristics ............................................. 8
Theory of Operation ...................................................................... 12
Control Loop............................................................................... 12
Current-Sense Configurations.................................................. 12
Current Limit .............................................................................. 13
Undervoltage Lockout ............................................................... 13
Shutdown..................................................................................... 13
Soft Start ...................................................................................... 13
Internal Shunt Regulators.......................................................... 13
Setting the Oscillator Frequency and Synchronization
Frequency .................................................................................... 13
Application Information: Boost Converter................................. 14
Duty Cycle ................................................................................... 14
REVISION HISTORY
12/06—Rev. 0 to Rev. A
Changes to Table 1............................................................................ 3
Changes to Table 2............................................................................ 5
Added Table 3.................................................................................... 5
Changes to Table 5.......................................................................... 19
Changes to Ordering Guide .......................................................... 31
7/06—Revision 0: Initial Version
Setting the Output Voltage........................................................ 14
Inductor Current Ripple............................................................ 14
Inductor Selection ...................................................................... 14
Input Capacitor Selection.......................................................... 15
Output Capacitor Selection....................................................... 15
Diode Selection........................................................................... 15
MOSFET Selection..................................................................... 16
Loop Compensation .................................................................. 16
Slope Compensation .................................................................. 17
Current Limit.............................................................................. 18
Light Load Operation ................................................................ 18
Recommended Component Manufacturers........................... 19
Layout Considerations................................................................... 20
Efficiency Considerations ............................................................. 21
Examples of Application Circuits................................................. 22
Standard Boost Converter—Design Example ........................ 22
Bootstrapped Boost Converter................................................. 23
SEPIC Converter Circuit ........................................................... 27
Low Voltage Power-Input Circuit ............................................ 27
LED Driver Application Circuits ............................................. 28
Related Parts.................................................................................... 30
Outline Dimensions ....................................................................... 31
Ordering Guide .......................................................................... 31
Rev. A | Page 2 of 32



Analog Devices ADP1621
ADP1621
SPECIFICATIONS
VIN = 5 V, RFREQ = 100 kΩ, fOSC = 200 kHz, TJ = −40°C to 125°C, unless otherwise noted.
Table 1.
Parameter
MAIN CONTROL LOOP
Internal Soft Start Time
PIN Supply Voltage1
IN Supply Voltage1
Shunt Regulation Voltage
Shunt Resistance
IN Quiescent Current
IN Shutdown Current
PIN Supply Current
Static Mode, No Switching
Shutdown Mode
Undervoltage Lockout Threshold at
IN Pin
FB Regulation Voltage
Symbol
tSS
VPIN
VIN
VSHUNT
RSHUNT
IIN
IPIN
VUVLO
VFB
Conditions
IIN = 3 mA, IPIN = 3 mA, TA = 25°C
IIN = 3 mA, IPIN = 3 mA
Current into IN = 8 mA to 12 mA
Current into PIN = 8 mA to 12 mA
VIN = 2.9 V to 5.5 V, VFB = 1.215 V
VIN = 2.9 V to 5.5 V, SDSN = GND
VFB = 1.3 V, VCOMP < VCOMP,ZCT, GATE = 0 V
SDSN = GND
VUVLO rising
VUVLO hysteresis
TA = 25°C
FB Input Current
Line Regulation2
Load Regulation3
Error Amplifier Transconductance
COMP Zero-Current Threshold
COMP Clamp High Voltage
Current-Sense Amplifier Gain
Peak Slope-Compensation Current at
CS Pin4
CS Pin Leakage Current
Shutdown Time
Thermal Shutdown Threshold5
Thermal Shutdown Hysteresis5
OSCILLATOR
Oscillator Frequency Range6
Oscillator Frequency
Oscillator Frequency Tempco
SDSN Input Level Threshold
SDSN Threshold Hysteresis
SDSN Internal Pull-Down Resistor
Synchronization Minimum Pulse Width
Synchronization Maximum Pulse Width
Synchronization Frequency
GATE Minimum On Time
GATE Minimum Off Time
Maximum Duty Cycle6, 7
Recommended Maximum
Synchronized Frequency Ratio6, 8
IFB
∆VFB/∆VIN
∆VFB/∆VCOMP
gm
VCOMP,ZCT
VCOMP,CLAMP
n
ISC,PK
ICS,LEAK
tSD
TTMSD
VFB = 1.215 V, TA = 25°C
2.9 V ≤ VIN ≤ 5 V, TJ = −40°C to +85°C
2.9 V ≤ VIN ≤ 5 V, TJ = −40°C to +125°C
VCOMP = 1.4 V to 1.5 V
TJ = −40°C to +85°C
TJ = −40°C to +125°C
VCS = 0 V to 100 mV maximum
across RS (GATE high)
VCS = 30 V (GATE low)
SDSN pin from high to low or left floating
fOSC
fOSC
fOSC,TC
VSDSN,THRESH
RSDSN
tSYNC,MIN
tSYNC,MAX
fSYNC
tON,MIN
tOFF,MIN
DMAX
fSYNC/fOSC
RFREQ = 65 kΩ, TA = 25°C
VIN = VPIN = 5 V
VSDSN = 0 V to VIN
VSDSN = 0 V to VIN
VFB = 1.215 V, VCOMP = 1.0 V
VFB = 1.215 V, VCOMP = 2.0 V
fSW = 200 kHz, RFREQ = 100 kΩ
fOSC = 200 kHz, RFREQ = 100 kΩ, fSYNC = fSW
Min Typ
Max Unit
2048
Cycles
2.9 VSHUNT V
2.9 VSHUNT V
5.4 5.6
5.7 V
5.2 5.6
6.0 V
13 Ω
1.8 3 mA
1 10 μA
2.2
1.203
1.197
−75
−1
0.85
1.9
1.9
7.5
55
1
1
2.5
−80
1.215
1.215
+25
0.02
0.02
−0.1
300
1.0
2.0
2.0
9.5
70
50
150
−10
10
10
2.8
1.227
1.233
+75
0.06
0.072
1.15
2.1
2.2
11.5
85
μA
μA
V
mV
V
V
nA
%/V
%/V
%
μS
V
V
V
V/V
μA
5 μA
μs
°C
°C
100 1500 kHz
255 325
395 kHz
±0.06
%/°C
1.5 1.7
1.9 V
−0.19
V
100 kΩ
45 100 ns
0.8/fSYNC
ns
110 1800 kHz
180 215 ns
190 230 ns
93 97 %
1.1 1.2
1.4
Rev. A | Page 3 of 32







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