ANALOG DEVICES ADP1612 Service Manual
600kHz/1.25MHz Step-Up
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Preliminary Technical Data
FEATURES
Fully integrated 1.5 A , 0.15 Ω power switch
Pin-selectable 600 kHz or 1.25 MHz PWM frequency
1.8 V minimum input voltage
Adjustable output voltage up to 20 V
Adjustable soft start
Input undervoltage lockout
Thermal shutdown
MSOP 8-lead package
APPLICATIONS
TFT LCD bias supplies
Portable applications
Industrial/instrumentation equipment
FUNCTIONAL BLOCK DIAGRAM
PWM DC-DC Switching Converter
ADP1612
GENERAL DESCRIPTION
The ADP1612 is a step-up dc-to-dc switching converter with an
integrated 1.5 A, 0.15 Ω power switch capable of providing an
output voltage as high as 20 V. With a package height of less
than 1.1 mm, the ADP1612 is optimal for space-constrained
applications such as portable devices or thin film transistor
(TFT) liquid crystal displays (LCDs).
The ADP1612 operates in pulse-width modulation (PWM)
current mode with up to 90% efficiency. Adjustable soft start
prevents inrush currents at startup. The pin-selectable
switching frequency and PWM current-mode architecture
allow for excellent transient response, easy noise filtering, and
the use of small, cost-saving external inductors and capacitors.
The ADP1612 is offered in the lead-free 8-lead MSOP and
operates over the temperature range of −40 °C to +85 °C.
Figure 1.Functional Block Diagram
Rev. PrA
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ADP1612 Preliminary Technical Data
www.BDTIC.com/ADI
TABLE OF CONTENTS
Features.............................................................................................. 1
Applications....................................................................................... 1
General Description ......................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 4
Thermal Resistance ...................................................................... 4
ESD Caution.................................................................................. 4
Pin Configuration and Function Descriptions............................. 5
Typical Performance Characteristics ............................................. 6
Theory of Operation ........................................................................ 7
Current-Mode PWM Operation................................................ 7
Frequency Selection ..................................................................... 7
Soft Start .........................................................................................7
Thermal Shutdown .......................................................................8
On/Off Control..............................................................................8
Applications Information.................................................................9
Setting the Output Voltage...........................................................9
Choosing the Input and Output Capacitors........................... 10
Diode Selection........................................................................... 10
Loop Compensation .................................................................. 10
Soft Start Capacitor.................................................................... 11
Typical Application Circuits ......................................................... 12
Layout Guidelines........................................................................... 13
Outline Dimensions....................................................................... 14
Ordering Guide............................................................................... 14
REVISION HISTORY
6/08—Rev. PrA
Rev. PrA | Page 2 of 14
Preliminary Technical Data ADP1612
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SPECIFICATIONS
Specifications with standard typeface are for TJ = 25 °C, and those in bold face type apply over the full operating temperature range (TJ =
-40 °C to + 125 °C). Unless otherwise specified, V
characterization using standard statistical quality control (SQC), unless otherwise noted.
Table 1.
Parameter Symbol Conditions Min Typ Max Unit
SUPPLY
Input Voltage VIN
Quiescent Current
Non-switching State IQ V
Non-switching State IQ V
Shutdown I
Switching State
Switching State
1
2
OUTPUT
Output Voltage V
Load Regulation I
Overall Regulation Line, load, temperature
REFERENCE
Feedback Voltage VFB TBD TBD TBD V
Line Regulation VIN = 2.5 V to 5.5 V TBD TBD %/V
ERROR AMPLIFIER
Transconductance G
Voltage Gain AV 60 dB
FB Input Bias Current V
SWITCH
SW On Resistance R
SW Leakage Current VSW = 20 V 0.01 10 μA
Peak Current Limit
3
I
OSCILLATOR
Oscillator Frequency fSW FREQ = GND TBD 600 TBD kHz
FREQ = VIN TBD 1.25 TBD MHz
Maximum Duty Cycle D
FREQ Pin Current I
SHUTDOWN
Shutdown Input Voltage Low VIL Non-switching state, V
Shutdown Input Voltage High VIH Switching state, V
Shutdown Input Bias Current I
SOFT START
SS Charging Current VSS = 0 V TBD 5 TBD μA
UNDERVOLTAGE LOCKOUT
4
UVLO Threshold Rising VIN rising 1.7
UVLO Threshold Falling VIN falling TBD 1.65 V
1
This parameter specifies the average current while switching internally and with SW (Pin 5) floating.
2
This parameter specifies the average current while switching internally and with SW (Pin 5) floating.
3
Current limit is a function of duty cycle. See Typical Performance Characteristics section for typical values over operating ranges.
4
UVLO
= 3.6 V. All limits at temperature extremes are guaranteed by correlation and
IN
1.8
= 1.5 V, FREQ = VIN 900 TBD μA
FB
= 1.5 V, FREQ = GND 900 TBD
FB
V
QSHDN
IQSW f
IQSW f
V
OUT
= 0 V 0.01 2 μA
SHDN
= 600 kHz, no load 2 TBD mA
SW
= 1.23 MHz, no load 4 TBD mA
SW
IN
= 10 mA to 150 mA, V
LOAD
= 8 V TBD mV/mA
OUT
TBD
MEA ΔI = 5 μA
= TBD V 10 TBD nA
FB
ISW = 1.0 A 150 TBD mΩ
DSON
V
CL
COMP = open, VFB = 1 V, FREQ = VIN TBD 90 TBD %
MAX
FREQ
V
SDHN
= 8 V TBD 1.5 TBD A
OUT
FREQ = GND TBD 5 TBD uA
= 1.8 V to 6 V 0.95 0.3 V
IN
= 1.8 V to 6 V 1.6 0.95 V
IN
= 1.6 V 1 TBD μA
SHDN
160 μA/V
6
20
%
1.8
V
V
V
Rev. PrA | Page 3 of 14
ADP1612 Preliminary Technical Data
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ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Rating
VIN, SHDN, FB to GND −0.3 V to 6.5 V
FREQ to GND -0.3 V to VIN+ 0.3 V
COMP to GND 1.0 V to 1.6 V
SS to GND -0.3 V to 1.3 V
SW to GND 21 V
RMS SW Pin Current 1.2 A
Operating Ambient Temperature
Range
Operating Junction Temperature
Range
Storage Temperature Range −65 °C to + 150 °C
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.
−40 °C to + 85 °C
−40 °C to + 125 °C
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 θJA θ
8 Lead MSOP
2-Layer Board
4-Layer Board
Maximum Power Dissipation
TBD TBD
TBD TBD
TBD TBD mW
Unit
JC
°C/W
°C/W
ESD CAUTION
Rev. PrA | Page 4 of 14
Preliminary Technical Data ADP1612
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PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
Figure 2.Pin Configuration
Table 4. Pin Function Descriptions
Pin No. Mnemonic Description
1 COMP Compensation input. Connect a series resistor-capacitor network from COMP to GND to compensate the
regulator.
2 FB Output voltage feedback input. Connect a resistive voltage divider from the output voltage to FB to set the
regulator output voltage.
3 SHDN Shutdown input. Drive SHDN low to shut down the regulator; drive SHDN high to turn it on.
4 GND Ground.
5 SW Switching output. Connect the power inductor from the input voltage to SW and connect the external rectifier
from SW to the output voltage to complete the step-up converter.
6 VIN Main power supply input. VIN powers the ADP1612 internal circuitry. Connect VIN to the input source voltage.
Bypass VIN to GND with a 10 μF or greater capacitor as close to the ADP1612 as possible.
7 FREQ Frequency Setting Input. FREQ controls the switching frequency. Connect FREQ to GND to program the oscillator
to 600 kHz, or connect FREQ to VIN to program it to 1.25 MHz. If FREQ is left floating, the part will default to
600kHz.
8 SS Soft start timing capacitor input. Connect a capacitor from SS to GND brings up the output slowly at power-up
and reduce in-rush current.
Rev. PrA | Page 5 of 14
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