Richtek RT8299GQW, RT8299GSP, RT8299ZQW, RT8299ZSP Schematic [ru]

Loading...

®

RT8299

3A, 24V, 500kHz Synchronous Step-Down Converter

General Description

The RT8299 is a high efficiency, monolithic synchronous step-downDC/DC converter with internal power MOSFETs. It achieves 3A of continuous output current over a wide input supply range from 3V to 24V with excellent load and line regulation. Current mode operation provides fast transient response and eases loop stabilization. Cycle- by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. Thermal shutdown provides reliable, fault tolerant operation. The low current shutdown mode provides output disconnection, enabling easy power management in battery powered systems.

Ordering Information

RT8299

Package Type

SP : SOP-8 (Exposed Pad-Option 1) QW: WDFN-10L 3x3 (W-Type)

Lead Plating System

G : Green (Halogen Free and Pb Free) Z : ECO (Ecological Element with

Halogen Free and Pb free)

Note :

Richtek products are :

RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.

Suitable for use in SnPb or Pb-free soldering processes.

Features

3V to 24V Input Voltage Range

3A Output Current

Internal N-MOSFETs

Current Mode Control

Fixed Frequency Operation : 500kHz

Output Adjustable from 0.8V to 15V

Up to 95% Efficiency

Stable with Low ESR Ceramic Output Capacitors

Cycle-by-Cycle Over Current Protection

Input Under Voltage Lockout

Output Under Voltage Protection

Thermal Shutdown Protection

SOP-8 (Exposed Pad) and 10-Lead WDFN Packages

RoHS Compliant and Halogen Free

Applications

Industrial and Commercial Low Power Systems

Computer Peripherals

LCD Monitors and TVs

Green Electronics/Appliances

Point of Load Regulation for High Performance DSPs, FPGAs, and ASICs

Pin Configurations

(TOP VIEW)

BOOT

 

 

8

VCC

VIN

2

GND

7

PGOOD

SW

3

6

EN

GND

4

9

5

FB

 

SOP-8 (Exposed Pad)

FB 1

PGOOD 2 EN 3

VCC 4

BOOT 5

 

10

GND

GND

9

SW

8

SW

 

 

7

VIN

11 6

VIN

WDFN-10L 3x3

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS8299-04 October 2014

www.richtek.com

 

1

RT8299

Marking Information

RT8299GSP

 

RT8299GQW

 

 

RT8299

RT8299GSP : Product Number

 

 

56= : Product Number

 

YMDNN : Date Code

 

56=YM

YMDNN : Date Code

 

GSPYMDNN

 

 

 

 

DNN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RT8299ZSP

 

RT8299ZQW

 

 

 

RT8299ZSP : Product Number

 

 

56 : Product Number

 

RT8299

 

 

 

YMDNN : Date Code

 

56 YM

YMDNN : Date Code

 

ZSPYMDNN

 

 

 

 

DNN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Typical Application Circuit

 

 

 

 

 

 

RT8299

 

 

VIN

CIN

VIN

BOOT

 

 

 

 

 

 

 

 

10µF x 2

 

 

CBOOT

 

 

 

 

 

 

Chip Enable

 

SW

L1

VOUT

EN

 

 

 

 

 

 

 

 

RT

R1

 

 

VCC

FB

COUT

 

CVCC

 

 

 

 

 

R2

 

1µF

GND

PGODD

Power Good

 

 

 

 

 

Table 1. Recommended Component Selection

VOUT (V)

R1 (k )

R2 (k )

RT (k )

L ( H)

COUT ( F)

1.2

15

30

50

2

22 x 2

2.5

25.5

12

40

3.6

22 x 2

3.3

16

5.1

30

4.7

22 x 2

5

27

5.1

18

6.8

22 x 2

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

DS8299-04 October 2014

2

 

Richtek RT8299GQW, RT8299GSP, RT8299ZQW, RT8299ZSP Schematic

RT8299

Functional Pin Description

Pin No.

Pin Name

Pin Function

SOP-8

WDFN-10L 3x3

(Exposed Pad)

 

 

1

5

BOOT

Bootstrap for High Side Gate Driver. Connect a 0.1 F or greater

ceramic capacitor from BOOT to SW pin.

 

 

 

2

6, 7

VIN

Supply Input Voltage. Must bypass with a suitably large ceramic

capacitor.

 

 

 

3

8, 9

SW

Switch Node. Connect to external LC filter.

4, 9

10, 11

GND

Ground. The exposed pad must be soldered to a large PCB and

(Exposed Pad)

(Exposed Pad)

connected to GND for maximum power dissipation.

 

 

 

Feedback Input. This pin is connected to the converter output. It

5

1

FB

is used to regulate the output of the converter to a desired value

via an internal resistive voltage divider. For an adjustable output,

 

 

 

 

 

 

an external resistive voltage divider is connected to this pin.

 

 

 

Enable Input. A logic high enables the converter; a logic low

6

3

EN

forces the RT8299 into shutdown mode, reducing the supply

current to less than 3 A. Attach this pin to VIN with a 100k pull

 

 

 

 

 

 

up resistor for automatic startup.

7

2

PGOOD

Power Good Output. The output of this pin is open drain.

8

4

VCC

Bias Supply.

Function Block Diagram

VIN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current Sense

 

 

 

 

Ramp

 

 

Amplifier

-

 

5k

Comparator

 

Generator

 

 

 

+

EN

 

-

Regulator

 

 

 

BOOT

 

3V

+

 

 

 

 

 

Oscillator

 

 

 

 

 

 

2V

 

 

S

Q

 

VCC

 

 

500kHz

 

Driver

 

 

 

 

 

 

 

 

 

 

+

 

 

 

 

Reference

 

 

R

Q

 

 

 

+

 

-PWM

 

 

 

 

 

 

 

FB

 

 

 

 

 

 

 

 

-

Error

Comparator

 

SW

 

 

 

Amplifier

OC Limit

 

 

 

 

 

300k

30pF

 

 

 

PGOOD

 

PGOOD

Clamp

 

 

 

 

 

 

 

 

 

Generator

 

 

 

 

 

 

 

 

 

1pF

 

 

 

GND

 

 

 

 

 

 

 

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS8299-04 October 2014

www.richtek.com

 

3

RT8299

Absolute Maximum Ratings (Note 1)

Supply Input Voltage, VIN ----------------------------------------------------------------------------------

−0.3 to 26V

Switching Voltage, SW ------------------------------------------------------------------------------------

−0.6 to (VIN + 0.3V)

< 20ns----------------------------------------------------------------------------------------------------------

−5V to 30V

Boot Voltage, BOOT ----------------------------------------------------------------------------------------

(VSW − 0.3V) to (VSW + 6V)

All Other Pins ------------------------------------------------------------------------------------------------

−0.3 to 6V

Power Dissipation, PD @ TA = 25°C

 

SOP-8 (Exposed Pad) -------------------------------------------------------------------------------------

1.333W

WDFN-10L 3x3 -----------------------------------------------------------------------------------------------

1.429W

Package Thermal Resistance (Note 2)

 

SOP-8 (Exposed Pad), θJA --------------------------------------------------------------------------------

75°C/W

SOP-8 (Exposed Pad), θJC -------------------------------------------------------------------------------

15°C/W

WDFN-10L 3x3, θJA -----------------------------------------------------------------------------------------

70°C/W

WDFN-10L 3x3, θJC -----------------------------------------------------------------------------------------

8.2°C/W

Lead Temperature (Soldering, 10 sec.) -----------------------------------------------------------------

260°C

Junction Temperature --------------------------------------------------------------------------------------

150°C

Storage Temperature Range ------------------------------------------------------------------------------

−65°C to 150°C

ESD Susceptibility (Note 3)

 

HBM (Human Body Model) ---------------------------------------------------------------------------------

2kV

MM (Machine Model) ----------------------------------------------------------------------------------------

200V

Recommended Operating Conditions

(Note 4)

 

 

 

 

 

Supply Voltage, VIN

-----------------------------------------------------------------------------------------

 

 

 

3V to 24V

 

 

 

Junction Temperature Range ------------------------------------------------------------------------------

 

 

 

−40°C to 125°C

 

Ambient Temperature Range ------------------------------------------------------------------------------

 

 

 

40°C to 85°C

 

Electrical Characteristics

 

 

 

 

 

 

 

(VIN = 12V, TA = 25°C, unless otherwise specified)

 

 

 

 

 

 

 

Parameter

Symbol

Test Conditions

Min

Typ

Max

 

Unit

Shutdown Current

 

ISHDN

VEN = 0V

 

--

--

3

 

A

Supply Current

 

 

VEN = 3V, VFB = 1V

--

1

--

 

mA

Upper Switch On Resistance

 

 

 

--

100

--

 

m

Lower Switch On Resistance

 

 

 

--

100

--

 

m

Switch Leakage

 

 

VEN = 0V, VSW = 0V or 12V

--

0

10

 

A

Current Limit

 

ILIM

VBOOT VSW = 4.8V

--

5.5

--

 

A

Oscillator Frequency

fOSC

VFB = 0.75V

425

500

575

 

kHz

Short Circuit Frequency

 

VFB = 0V

 

--

150

--

 

kHz

Maximum Duty Cycle

DMAX

VFB = 0.8V

 

--

93

--

 

%

Minimum On-Time

 

tON

 

 

--

100

--

 

ns

Feedback Voltage

 

VFB

4.5V VIN 24V

788

800

812

 

mV

EN Input

 

Logic-High

VIH

 

 

2

--

5.5

 

V

Threshold Voltage

 

Logic-Low

VIL

 

 

--

--

0.4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

 

www.richtek.com

DS8299-04 October 2014

4

 

RT8299

Parameter

Symbol

Test Conditions

Min

Typ

Max

Unit

Under Voltage Lockout

VUVLO

VIN Rising

--

2.8

--

V

Threshold

 

 

 

 

 

 

Under Voltage Lockout

VUVLO

 

--

300

--

mV

Threshold Hysteresis

 

 

 

 

 

 

 

Power Good Threshold

 

VOUT Rising, with Respect to VFB

--

90

--

%

 

VOUT Falling, with Respect to VFB

--

70

--

 

 

 

VCC Regulator

 

 

--

5

--

V

 

 

 

 

 

 

 

VCC Load Regulation

 

ICC = 5mA

4

--

4

%

Soft-Start Period

tSS

 

--

2

--

ms

Thermal Shutdown

TSD

 

--

150

--

C

Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may affect device reliability.

Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package.

Note 3. Devices are ESD sensitive. Handling precaution is recommended.

Note 4. The device is not guaranteed to function outside its operating conditions.

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS8299-04 October 2014

www.richtek.com

 

5

+ 11 hidden pages