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LT1506CR-3.3#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24
1
LT1506
4.5A, 500kHz Step-Down
Switching Regulator
■
Constant 500kHz Switching Frequency
■
Easily Synchronizable
■
Operates with Input as Low as 4V
■
Uses All Surface Mount Components
■
Inductor Size Reduced to 1.8
µ
H
■
Saturating Switch Design: 0.07Ω
■
Shutdown Current: 20µA
■
Cycle-by-Cycle Current Limiting
The LT
®
1506 is a 500kHz monolithic buck mode switching
regulator functionally identical to the LT1374 but optimized
for lower input voltage applications. It will operate over a
4V to 15V input range compared with 5.5V to 25V for the
LT1374. A 4.5A switch is included on the die along with all
the necessary oscillator, control and logic circuitry. High
switching frequency allows a considerable reduction in the
size of external components. The topology is current mode
for fast transient response and good loop stability. Both
fixed output voltage and adjustable parts are available.
A special high speed bipolar process and new design tech-
niques achieve high efficiency at high switching frequency.
Efficiency is maintained over a wide output current range
by keeping quiescent supply current to 4mA
and by utiliz-
ing a supply boost
capacitor to saturate the power switch.
The LT1506 fits into standard 7-pin DD and fused lead
SO-8 packages. Full cycle-by-cycle short-circuit protection
and thermal shutdown are provided. Standard surface
mount external parts are used, including the inductor and
capacitors. There is the optional function of shutdown or
synchronization. A shutdown signal reduces supply current
to 20µA. Synchronization allows an external logic level sig-
nal to increase the internal oscillator from 580kHz to 1MHz.
■
Portable Computers
■
Battery-Powered Systems
■
Battery Charger
■
Distributed Power
, LTC and LT are registered trademarks of Linear Technology Corporation.
LOAD CURRENT (A)
0
EFFICIENCY (%)
90
85
80
75
70
2.0 2.5 3.0 3.5
1506 TA02
0.5 1.0 1.5 4.0
V
OUT
= 3.3V
V
IN
= 5V
L = 10µH
Efficiency vs Load Current
5V to 3.3V Down Converter
BOOST
LT1506-3.3
V
IN
OUTPUT
3.3V
4A
INPUT
5V
1506 TA01
C2
0.68µF
C
C
1.5nF
D1
MBRS330T3
C1
100µF, 10V
SOLID
TANTALUM
C3
10µF TO
50µF
CERAMIC
D2
1N914
L1
5µH
V
SW
SENSESHDN
OPEN
OR
HIGH
= ON
GND
V
C
+
+
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
2
LT1506
ABSOLUTE MAXIMUM RATINGS
W
WW
U
Input Voltage .......................................................... 16V
BOOST Pin Above Input Voltage ............................. 15V
SHDN Pin Voltage..................................................... 7V
FB Pin Voltage (Adjustable Part)............................ 3.5V
FB Pin Current (Adjustable Part)............................ 1mA
Sense Voltage (Fixed 3.3V Part) ............................... 5V
SYNC Pin Voltage ..................................................... 7V
Operating Junction Temperature Range
LT1506C............................................... 0°C to 125° C
LT1506I ........................................... –40°C to 125°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS
Feedback Voltage (Adjustable) 2.39 2.42 2.45 V
All Conditions ● 2.36 2.48 V
Sense Voltage (Fixed 3.3V) 3.25 3.3 3.35 V
All Conditions ● 3.23 3.37 V
SENSE Pin Resistance 4 6.6 9.5 kΩ
Reference Voltage Line Regulation 4.3V ≤ V
IN
≤ 15V 0.01 0.03 %/V
Feedback Input Bias Current ● 0.5 2 µA
Error Amplifier Voltage Gain (Notes 2, 8) 200 400
Error Amplifier Transconductance ∆I (V
C
) = ±10µA (Note 8) 1500 2000 2700 µMho
● 1000 3100 µMho
V
C
Pin to Switch Current Transconductance 5.3 A/V
Error Amplifier Source Current V
FB
= 2.1V or V
SENSE
= 2.9V ● 140 225 320 µA
Error Amplifier Sink Current V
FB
= 2.7V or V
SENSE
= 3.7V ● 140 225 320 µA
V
C
Pin Switching Threshold Duty Cycle = 0 0.9 V
V
C
Pin High Clamp 2.1 V
Switch Current Limit V
C
Open, V
FB
= 2.1V or V
SENSE
= 2.9V, DC ≤ 50% ● 4.5 6 8.5 A
Slope Compensation DC = 80% 0.8 A
T
J
= 25°C, V
IN
= 5V, V
C
= 1.5V, Boost = V
IN
+ 5V, switch open, unless otherwise noted.
PACKAGE/ORDER INFORMATION
W
U
U
ORDER PART
NUMBER
ORDER PART
NUMBER
LT1506CR
LT1506CR-3.3
LT1506CR-SYNC
LT1506CR-3.3 SYNC
LT1506IR
LT1506IR-3.3
LT1506IR-SYNC
LT1506IR-3.3 SYNC
T
JMAX
= 125°C, θ
JA
= 30°C/W
WITH PACKAGE SOLDERED TO 0.5 SQUARE INCH
COPPER AREA OVER BACKSIDE GROUND PLANE OR
INTERNAL POWER PLANE. θ
JA
CAN VARY FROM 20°C/W
TO >40°C/W DEPENDING ON MOUNTING TECHNIQUES
1506I
506I33
1506
150633
S8 PART MARKING
LT1506CS8
LT1506CS8-3.3
LT1506IS8
LT1506IS8-3.3
*Default is the adjustable output voltage device with FB pin and shutdown function. Option -3.3 replaces FB with SENSE pin for fixed 3.3V output
applications. -SYNC replaces SHDN with SYNC pin for applications requiring synchronization. Consult factory for Military grade parts.
FB OR SENSE*
BOOST
V
IN
GND
V
SW
SYNC OR SHDN*
V
C
R PACKAGE
7-LEAD PLASTIC DD PAK
FRONT VIEW
TAB
IS
GND
7
6
5
4
3
2
1
1
2
3
4
8
7
6
5
TOP VIEW
S8 PACKAGE
8-LEAD PLASTIC SO
V
IN
BOOST
GND**
V
SW
SYNC
SHDN
V
C
FB OR
SENSE*
θ
JA
= 80°C/W
**WITH FUSED (GND) GROUND PIN
CONNECTED TO GROUND PLANE OR
LARGE LANDS
(Note 1)
3
LT1506
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS
Switch On Resistance (Note 7) I
SW
= 4.5A 0.07 0.1 Ω
● 0.13 Ω
Maximum Switch Duty Cycle V
FB
= 2.1V or V
SENSE
= 2.9V 90 93 %
● 86 93 %
Switch Frequency V
C
Set to Give 50% Duty Cycle 460 500 540 kHz
● 440 560 kHz
Switch Frequency Line Regulation 4.3V
≤ V
IN
≤ 15V ● 0 0.15 %/V
Frequency Shifting Threshold on FB Pin ∆f = 10kHz ● 0.8 1.0 1.3 V
Minimum Input Voltage (Note 3) ● 4.0 4.3 V
Minimum Boost Voltage (Note 4) I
SW
≤ 4.5A ● 2.3 3.0 V
Boost Current (Note 5) I
SW
= 1A ● 20 35 mA
I
SW
= 4.5A ● 90 140 mA
Input Supply Current (Note 6) ● 3.8 5.4 mA
Shutdown Supply Current V
SHDN
= 0V, V
SW
= 0V, V
C
Open 15 50 µA
● 75 µA
Lockout Threshold V
C
Open ● 2.3 2.38 2.46 V
Shutdown Thresholds V
C
Open Device Shutting Down ● 0.13 0.37 0.60 V
Device Starting Up ● 0.25 0.45 0.7 V
Synchronization Threshold ● 1.5 2.2 V
Synchronizing Range 580 1000 kHz
SYNC Pin Input Resistance 40 kΩ
T
J
= 25°C, V
IN
= 5V, V
C
= 1.5V, Boost = V
IN
+ 5V, switch open, unless otherwise noted.
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: Gain is measured with a V
C
swing equal to 200mV above the
switching threshold level to 200mV below the upper clamp level.
Note 3: Minimum input voltage is not measured directly, but is guaranteed
by other tests. It is defined as the voltage where internal bias lines are still
regulated so that the reference voltage and oscillator frequency remain
constant. Actual minimum input voltage to maintain a regulated output will
depend on output voltage and load current. See Applications Information.
Note 4: This is the minimum voltage across the boost capacitor needed to
guarantee full saturation of the internal power switch.
Note 5: Boost current is the current flowing into the boost pin with the pin
held 5V above input voltage. It flows only during switch on time.
Note 6: Input supply current is the bias current drawn by the input pin
with switching disabled.
Note 7: Switch on resistance is calculated by dividing V
IN
to V
SW
voltage
by the forced current (4.5A). See Typical Performance Characteristics for
the graph of switch voltage at other currents.
Note 8: Transconductance and voltage gain refer to the internal amplifier
exclusive of the voltage divider. To calculate gain and transconductance
refer to SENSE pin on fixed voltage parts. Divide values shown by the ratio
V
OUT
/2.42.
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LT1506CR-3.3#TRPBF

Mfr. #:
Buy LT1506CR-3.3#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 4.5A, 500kHz Buck Sw Reg
Lifecycle:
New from this manufacturer.
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