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Part: LT1612
Category:
Power Management
-> Regulators
-> Switching Regulators
-> Step-Down
Description: LT1612, 500mA Synchronous, Step-down 800kHz PWM DC/DC Converter
Company: Linear Technology Corporation
Datasheet: Download LT1612 datasheet File size : 550 kB
Request For quote: Find where to buy LT1612
Datasheet text preview:
LT1612 Synchronous, Step-Down 800kHz PWM DC/DC Converter
FEATURES
s s s s s s s s
DESCRIPTIO
Operates from Input Voltage As Low As 2V Internal 0.7A Synchronous Switches Uses Ceramic Input and Output Capacitors 620mV Reference Voltage 800kHz Fixed Frequency Switching Programmable Burst Mode Operation Low Quiescent Current: 160µA 8-Lead MSOP or SO Package
APPLICATIO S
s s s s
The LT®1612 is an 800kHz, synchronous step-down DC/ DC converter that operates from an input voltage as low as 2V. Internal 0.45 switches deliver output currents up to 500mA, and the 800kHz switching frequency allows the use of small, low value ceramic input and output capacitors. Input voltage ranges from 5.5V down to 2V and output voltage can be set as low as the 620mV reference. The device features Burst ModeTM operation, keeping efficiency high at light loads. Burst Mode operation can be defeated by pulling the MODE pin high, enabling constant switching throughout the load range for low noise. No-load quiescent current is 160µA and shutdown current is less than 1µA. The device is available in 8-lead SO and MSOP packages.
, LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation.
Portable Devices Lithium-Ion Step-Down Converters 5V to 3.3V Conversion 2-Cell Alkaline Step-Down Converters
TYPICAL APPLICATION
0.1µF VIN 2V VIN SHDN LT1612 C1 10µF MODE VC 33.2k 330pF FB GND R2 232k 1% R1 215k 1% C2 68µF 3.15V BOOST SW 100pF L1 10µH VOUT 1.2V 500mA
Efficiency for LT1612 vs Linear Regulator VOUT = 1.2V
90 80 VIN = 2V VIN = 3V VIN = 2V (LINEAR)
EFFICIENCY (%)
70 60 50 40
VIN = 3V (LINEAR) 10 100 LOAD CURRENT (mA) 500
1612 · F01b
C1: TAIYO-YUDEN JMK325BJ106MN C2: PANASONIC EEFCDOF680R L1: SUMIDA CD43-100
1612 F01a
30
Figure 1. 2V to 1.2V Converter
U
sn1612 1612fs
U
U
1
LT1612
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VIN) ..... 5.5V SW Pin Voltage ....... 5.5V FB Pin Voltage ..... VIN + 0.3V VC Pin Voltage .. 2V SHDN Pin Voltage ......... 5.5V MODE Pin Voltage ........ 5.5V
PACKAGE/ORDER INFORMATION
ORDER PART NUMBER
TOP VIEW VC FB VIN GND 1 2 3 4 8 7 6 5 SHDN MODE BOOST SW
LT1612EMS8 MS8 PART MARKING LTMS
MS8 PACKAGE 8-LEAD PLASTIC MSOP
TJMAX = 125°C, JA = 200°C/ W
Consult factory for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER IQ Quiescent Current
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C, VIN = VSHDN = 3V
CONDITIONS MODE = 5V MODE = 0V, Not Switching SHDN = 0V
q q q q
V FB
FB Voltage FB Line Regulation FB Pin Bias Current (Note 3)
q q
gm
Error Amplifier Transconductance Min Input Voltage Max Input Voltage 2
f OSC
Oscillator Frequency
q
fOSC Line Regulation Maximum Duty Cycle
q
Shutdown Threshold
Minimum Voltage for Active Maximum Voltage for Shutdown
2
U
U
W
WW U
W
(Note 1)
BOOST Pin Voltage ...... VIN + 5.5V Junction Temperature .......... 125°C Operating Temperature Range (Note 2) ... 40°C to 85°C Storage Temperature Range ........ 65°C to 150°C Lead Temperature (Soldering, 10 sec)......... 300°C
TOP VIEW VC 1 FB 2 VIN 3 GND 4 8 7 6 5 SHDN MODE BOOST SW
ORDER PART NUMBER LT1612ES8 S8 PART MARKING 1612
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 125°C, JA = 120°C/ W
MIN
TYP 1 160
MAX 2 220 1 0.635 0.635 0.15 50
UNITS mA µA µA V V %/V nA µmhos V V kHz kHz %/ V % %
0.605 0.60
0.62 0.62 0.02 7 250
5.5 700 550 85 80 2 0.2 800 1 90 900 1100
q q
V V
sn1612 1612fs
LT1612
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER SHDN Pin Current BOOST Pin Current Switch Current Limit (Note 4)
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C, VIN = VSHDN = 3V
CONDITIONS SHDN = 2V SHDN = 5V BOOST = VIN + 2V Duty Cycle = 0% MODE = OV MODE = 5V Burst Mode Operation Current Limit Switch Voltage Drop Rectifier Voltage Drop SW Pin Leakage MODE = 0V ISW = 500mA IRECT = 500mA VSW = 5V, VSHDN = 0V
q q q
MIN
TYP 10 30 4
MAX 15 45 900 900
UNITS µA µA mA mA mA mA
600 550
710 650 180 200 300
280 400 1
mV mV µA
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT1612E is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the 40°C to 85°C operating
temperature range are assured by design, characterization and correlation with statistical process controls. Note 3: Bias current flows out of the FB pin. Note 4: Duty cycle affects current limit due to slope compensation.
TYPICAL PERFOR A CE CHARACTERISTICS
FB Voltage vs Temperature
0.64
QUIESCENT CURRENT (µA)
0.63
FB PIN CURRENT (nA)
FB VOLTAGE (V)
0.62
0.61
0.60
0.59 50
25
0 25 50 TEMPERATURE (°C)
UW
75
1612 · G01
Quiescent Current vs Temperature
190 MODE = 0V 180 170 160 150 140 130 120 110
100 0 2 4 6 8 10 12 14 16 18
FB Pin Bias Current
100 50
25
0 25 50 TEMPERATURE (°C)
75
100
20 50
25
25 50 0 TEMPERATURE (°C)
75
100
1612 · G02
1612 · G03
sn1612 1612fs
3
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