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SX6030

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SX60303A Step-Down Voltage Regulator

DESCRIPITION

The SX6030 series of regulators are monolithic

integrated circuits that provide all the

active functions for a step-down (buck) switching regulator, capable of driving 3A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V and an ADJ output version.

Requiring a minimum number of external components, these regulators are simple to use and include internal frequency compensation and a fixed-frequency oscillator. The SX6030 series offers a

high-efficiency replacement for popular three-terminal linear

regulators. It substantially reduces the size of the heat sink, and in some cases no heat sink is required. A standard series of inductors optimized for use with the SX6030 are

available from several different manufacturers. This feature greatly simplifies the design of switch-mode power supplies.

Other features include a guaranteed ±4% tolerance on output voltage within specified input voltages and output load conditions, and ±10% on the oscillator frequency. External shutdown is included, featuring 50 µA (typical) standby current. The output switch includes cycle-by-cycle current limiting, as well as thermal shutdown for full protection under fault conditions.

FEATURES APPLICATIONS

z 3.3V, 5V, 12V and adjustable output versions z Guaranteed 3A output current

z Adjustable version output voltage range,1.23V to

57V±4% max over line and load conditions z 52 kHz fixed frequency internal oscillator

z TTL shutdown capability, low power standby mode z High efficiency

z Uses readily available standard inductors z Thermal shutdown and current limit protection z Wide input voltage range up to 60V z Requires only 4 external components

z Simple high-efficiency step-down (buck) regulator z Efficient pre-regulator for

linear regulators

z On-card switching regulatorsz Positive to negative converter (Buck-Boost)

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SX6030

CONNECTION DIAGRAMS

BLOCK DIAGRAM

3.3V R2=1.7K 5V R2=3.1K For ADJ Version R1=open, R2=0Ω

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SX6030

PIN FUNCTIONS

+VIN —This is the positive input supply for the IC switching regulator. A suitable input bypass capacitor must be present at this pin to minimize voltage transients and to supply the switching currents needed by the regulator. Ground —Circuit ground.

Output —Internal switch, the voltage at this pin switches between (+VIN VSAT) and approximately -0.5V. To minimize coupling to sensitive circuitry, the PC board copper area connected to this pin should be kept to a minimum.

FeedBack —Senses the regulated output voltage to complete the feedback loop.

—Allows the switching regulator circuit to be shut down using logic level signals. Pulling this pin below a threshold voltage of approximately 1.5V turns the regulator on, and shutdown feature is not needed, the ON/OFF pin can be wired to the ground pin or it can be left open, in either case the regulator will be in the ON condition.

ABSOLUTE MAXIMUM RATINGS (Ta=25°C) *

Characteristic Value Unit Maximum supply voltage 63 V

-0.3V≤V≤+VIN V ON /OFF pin input voltage Output voltage to ground(steady state) Power dissipation

Storage temperature range Maximum junction temperature

ESD susceptibility (Human Body Model)

-1

Internally limited

-65~+150

2 150

V °C kV °C

RECOMMENDED OPERATING CONDITIONS

Characteristic Symbol Value Unit Supply Voltage

Operating temperature range

VCC

8～60 -40～+125

V °C

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ELECTRICAL CHARACTERISTICS

(Specifications with standard type face are for TJ = 25°C,)

Parameter

Symbol

SX6030

Condition

Min. *2

Typ. Max. Unit Device Parameters

Feedback bias Adjustable version

current only, VOUT=5V Oscillator

*8 fO frequency

VSAT saturation voltage VSAT IOUT=3A *4 Max. duty cycle(ON) Current limit

DC ICL *5 *4,8 Output=0V *6,7 Output=-1V *10

50 100 nA 47 52 58 kHz 93

1.4 98

1.8 2.0

V % mA

4.2 5.8 6.9 A 7.5

30 mA Output leakage IL

current

Quiescent current Standby quiescent current ON/OFF Control ON/OFF pin logic input level

ON/OFF pin input current

IQ *6 5 10 mA 50 200 µA ISTBY ON/OFF PIN=5V VIH

=VOUT0V 2.0 V VOUT=nominal output

VIL 0.8 V voltage

30IIH ON/OFF =pin5V(OFF) 12µA =pin0V(ON) 0IIL ON/OFF 10

µA

SX6030 3.3V System Parameters *3

8V≤VIN≤60V 3.234 3.3 3.366 V Output voltagde VOUT

3.168 3.3 3.450 V 0.5A≤ILOAD≤3A

Efficiency =VIN=12V,Iη LOAD3A 75 % SX6030 5.0V System Parameters *3

8V≤VIN≤60V 4.9 5.0 5.1 V Output voltagde VOUT 5.0 4.8 5.225 V 0.5A≤ILOAD≤3A

Efficiency VIN=12V,I=η LOAD3A 77 % System Parameters *3

11.76 12.0 12.24 V 15V≤VIN≤60V Output voltagde VOUT 11.52 12.0 12.48 V 0.5A≤ILOAD≤3A Efficiency =VIN=15V,Iη LOAD3A 88 % SX6030 ADJ System Parameters *3

8V≤VIN≤60V

Output voltagde VOUT 0.5A≤ILOAD≤3A

VOUT=5V

VIN=12V,ILOAD=3A

Efficiency η

VOUT=5V

1.193 1.230 1.267 1.217 1.230 1.243 V V

SX6030 12V

77 % * 1 Absolute Maximum Ratings indicates limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be

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the best conditions, see the Electrical Characteristics.

SX6030

functional, but specific performance is not guaranteed. For guaranteed specifications and

* 2 All limits guaranteed at room temperature (standard type face) and at temperature extremes(bold type face). All room temperature limits are 100% production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods.

* 3 External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator system performance. * 4 Output pin sourcing current. No diode, inductor or capacitor connected to output pin. * 5 Feedback pin removed from output and connected to 0V.

* 6 Feedback pin removed from output and connected to +12V for the 3.3V, 5V, and the ADJ version, to force the output transistor switch OFF. * 7 VIN = 60V

* 8 The oscillator frequency reduces to approximately 11 KHz in the event of an output short or an overload which causes the regulated output voltage to drop approximately 40% from the nominal output voltage. The self-protection feature lowers the average power dissipation of the minimum duty cycle from 5% down to approximately 2%.

TEST CIRCUIT

SX6030SX6030

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APPLICATION CIRCUIT

Typical

SX6030

Vin

SX6030

Low Noise Vin

SX6030

APPLICATION INFORMATION

Careful layout is important with any switching regulator. Rapidly switching currents associated with wiring inductance generate voltage transients which can cause problems. To minimize inductance and ground loops, the lengths of the leads indicated by heavy lines in Figure 1 below should be kept as short as possible. Single point grounding or ground plane construction should be used for best results. When using the Adjustable version, place the programming resistors as close as possible toSX6030, to keep the sensitive feedback wiring short.

INPUT CAPACITOR CIN

A low ESR aluminum or tantalum bypass capacitor is needed between the input pin and ground pin. It must be located near the regulator using short leads. This capacitor prevents large voltage transients from appearing at the input, and provides the instantaneous current needed each time the switch turns on. Selecting an input capacitor requires consulting the manufacturers data sheet for maximum allowable RMS ripple current. For a maximum ambient temperature of 40°C, a general guideline would be to select a capacitor with a ripple current rating of approximately 50% of the DC load current. For ambient

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SX6030

temperatures up to 70°C, a current rating of 75% of the DC load current would be a good choice for a conservative design. The capacitor voltage rating must be at least 1.25 times greater than the maximum input voltage, and often a much higher voltage capacitor is needed to satisfy the RMS current requirements. OUTPUT CAPACITOR COUT

An output capacitor is required to filter the output and provide regulator loop stability. Low impedance or low ESR Electrolytic or solid tantalum capacitors designed for switching regulator applications must be used. When selecting an output capacitor, the important capacitor parameters are; the 100 kHz Equivalent Series resistance (ESR), the RMS ripples current rating, voltage rating, and capacitance value. For the output capacitor, the ESR value is the most important parameter. The output capacitor requires an ESR value that has an upper and lower limit. For low output ripple voltage, a low ESR value is needed. This value is determined by the maximum allow able output ripple voltage, typically 1% to 2% of the output voltage. But if the selected capacitor’s ESR is extremely low, there is a possibility of an unstable feedback loop, resulting in an oscillation at the output. CATCH DIODE D1

Buck regulators require a diode to provide a return path for the inductor current when the switch turns off. This must be a fast diode and must be located close to the SX6030 using short leads and short printed ci

rcuit traces. Because of their very fast

switching speed and low forward voltage drop, Schottky diodes provide the best performance, especially in low output voltage applications (5V and lower). Ultra fast recovery, or High-Efficiency rectifiers are also a good choice, but some types with an abrupt turnoff characteristic may cause instability or EMI problems. INDUCTOR SELECTION L

All switching regulators have two basic modes of operation; continuous and discontinuous. The difference between the two types relates to the inductor current, whether it is flowing continuously, or if it drops to zero for a period of time in the normal switching cycle. Each mode has distinctively different operating characteristics, which can affect the regulators performance and requirements. Most switcher designs will operate in the discontinuous mode when the load current is low. The SX6030 (or any of the Si

mple Switcher family) can be used for both continuous and

discontinuous modes of operation. There is a formula for general applications:

(Note The unit of voltage is V, the unit of current is A)

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SX6030

CHARACTERISTICS CURVE

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SX6030

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SX6030

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SX6030OUTLINE DRAWING

TO-220T Unit:mm

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SX6030

TO-263 U nit:mm

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