Document
Low Input Voltage, High Efficiency, 4A Integrated FET Synchronous Step down DC/DC Regulator
POWER MANAGEMENT Description
The SC4624 is a highly integrated synchronous step-down DC/DC regulator designed for low input voltage range of 2.3V to 5.5 Volts. It can deliver 4A continuous output current with the output voltage as low as 0.5 Volts. The internal low RDS(ON) synchronous power switches eliminate the need for external Schottky diode while delivering overall converter efficiency up to 95%.
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SC4624
Features
u VIN Range: 2.3 – 5.5V u 4A Continuous Output Current u Adjustable Output Voltage 0.5V to Vin u Low RDS(ON) integrated FETs: 75mΩ and 47mΩ u Up to 95% Efficiency u Synchronizable and Programmable Frequency: 200kHz – 2MHz u Power Good Monitor u <1µA of Shutdown Current u Programmable Soft Start u Programmable Current Limit u Over Temperature protection u -40 to +85 °C Ambient Temperature Range u Starts into pre-biased output u 4x4mm MLPQ-20 and SOIC-16EDP packagesWEEE and RoHS Compliant
A power good pin is available to monitor the output voltage status. Operating frequency is adjustable from 200 kHz to 2MHz with a single resistor and it can be synchronized to an external clock. The SC4624 offers adjustable current limit, soft start and over temperature protection to safeguard the device under extreme operating conditions. The soft start provides a controlled output voltage ramp up at startup. When a logic low is applied to the Enable pin, the SC4624 enters the shutdown mode and it consumes less than 1µA of current. The SC4624 is available in 4x4 MLPQ-20 and SOIC-16EDP package, and it is rated over -40°C to +85°C ambient temperature range.
Applications
Low Voltage Distributed DC-DC Converters Telecommunication Power Supplies Portable Equipment xDSL
Typical Application Circuit
R4 C11 L1 R5 C9 R6 R2 C3 PVIN SYNC/EN PGOOD VCC FB R1 R9 C1 L2 PH R7 R8 C8 C4
Vin
Vout
SC4624
SS ISET FS COMP
C2
AGND
Revision: July 24, 2007
PGND
C7
C5 R3 R11
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SC4624
POWER MANAGEMENT Pin Configuration
5 4 D
3
2
1
Ordering Information
Device Top Mark SC 4624 SC4624 Package MLPQ-20 SO-16 EDP
D
Top View
PVIN2
PGND2
PH3
PH2
PH1
SC4624MLTRT (1) (2) SC4624SETRT (1) (2)
ISET www.DataSheet4U.com SS
C
PVIN1
20 1
16 15
PGND1 AGND VCC
SC4624EVB-MLPQ
C
VCC
B
FS
T
5 6 11 10
SYNC/EN
SC4624EVB-SO
Evaluation Board
FB
Notes: (1) Available in tape and reel only. A reel contains 3,000 devices for MLPQ-20 package and 2,500 devices for SO-16 package. (2) Available in lead-free package only. Device is WEEE and RoHS compliant.
B
A
θJA= 29°C/W; θJC= 2.5°C/W.
5 4 3 2 1
PGOOD
20Pin MLPQ
A
5
D
4
Top View
3
COMP
2
NC
NC
NC
1
D
SYNC/EN PGND1 PGND2 PH1 PH2
1 2 3 4 5 6 7 8 T
16 15 14 13 12 11 10 9
AGND VCC FB
C
COMP VCC SS FS
C
PVIN1
B
PGOOD
B
PVIN2 ISET
16Pin SOIC-EDP
A
θJA= 31°C/W; θJC= 3.9°C/W.
5 4 3 2 1
A
2007 Semtech Corp.
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SC4624
POWER MANAGEMENT Absolute Maximum Ratings
Parameter Supply Voltage PVIN to VCC FB, COMP, ISET, SYNC/EN, FS, SS, PGOOD to AGND
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Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied.
Symbol PVIN, VCC
Maximum -0.3 to 6 +/- 0.3 -0.3 to VCC+ 0.3 +/- 0.3
Units V V V V V V °C °C °C
PGND to AGND PHASE Voltage to PGND PHASE Pulse Voltage to PGND Tpulse < 50ns Storage Temperature Range Junction Temperature IR Reflow Temperature VPHASE VPHASE TSTG TJ TP
-0.3 to PVIN+ 0.3 -3 to PVIN+ 2 -40 to 150 150 260
Recommended Operating Conditions
The Performance is not guarantied if exceeding the specifications below.
Parameter Power Supply Input Voltage Operating Range Ambient Temperature Range Junction Temperature Max. Output Current
Symbol
Conditions
Min
Typ
Max
Units
VIN TA TJ IOUTMAX
2.3 -40 -40 0
5.5 85 125 4
V °C °C A
Electrical Characteristics
Unless otherwise specified, VIN= VCC=SYNC/EN=3.3V, ROSC=51.1KΩ, RISET=27.4KΩ, TA = -40°C to 85°C
Parameter Power Supply Start Threshold Voltage, UVLO Hysteresis Voltage, UVLO Supply Current, Shutdown Supply Current, Operating
Symbol
Conditions
Min
Typ
Max
Units
VIUV VIUVHY ISD IQswitching IQL
VIN Rising
2 120
2.25
V mV
VSYNC = 0V FB = COMP, No Load FB = 0.6V, No Load
0.2 7 3.5
1 10 7
µA mA mA
2007 Semtech Corp.
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SC4624
POWER MANAGEMENT Electrical Characteristics (Cont.)
Unless otherwise specified, VIN= VCC=SYNC/EN=3.3V, ROSC=51.1KΩ, RISET=27.4KΩ, TA = -40°C to 85°C.
Parameter Thermal Shutdown Thermal Shutdown Trip Point Thermal Shutdown Hysteresis Synchronization, Enable Input
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Symbol
Conditions
Min
Typ
Max
Units
TOTP TOTP_HYS
Temperature Rising
160 10
°C °C
SYNC/EN Threshold Frequency Range, SYNC Oscillator Osciilator Frequency Range Osciilator Frequency Accuracy Ramp Peak to Valley(1) Ramp Peak Voltage(1) Ram.