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

®

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

RT8299

General Description

The RT8299 is a high efficiency , monolithic synchronous
step-down DC/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. Cycle­by-cycle current limit provides protection against shorted
outputs and soft-start eliminate s input current surge during
start-up. Thermal shutdown provides reliable, fault tolera nt
operation. The low current shutdown mode provides output
disconnection, enabling ea sy 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 require-

ments 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-MOSFET s





 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-Le ad WDFN Package s





 RoHS Compliant and Halogen Free



Applications

 Industrial and Commerci al Low Power Systems
 Computer Peripherals
 LCD Monitors a nd TVs
 Green Electronics/Appliance s
 Point of Load Regulation for High Performance DSPs,

FPGAs, and ASICs

Pin Configurations

(TOP VIEW)

GND

8

VCC

7

PGOOD

6

9

EN

5

FB

BOOT

VIN
SW

GND

2
3
4

SOP-8 (Exposed Pad)

GND

11

10

GND

9

SW

8

SW

7

VIN

6

VIN

FB

PGOOD

EN

VCC

BOOT

1
2
3
4
5

WDFN-10L 3x3

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RT8299

Marking Information

RT8299GSP

RT8299GSP : Product Number

RT8299

YMDNN : Date Code

GSPYMDNN

RT8299ZSP

RT8299ZSP : Product Number

RT8299

YMDNN : Date Code

ZSPYMDNN

Typical Application Circuit

V

IN

Chip Enable

C

VCC

1µF

C

IN

10µF x 2

VIN

EN

VCC

GND

RT8299

BOOT

SW

FB

PGODD

RT8299GQW

56=YM

DNN

RT8299ZQW

56 YM

DNN

C

BOOT

R

T

Power Good

56= : Product Number
YMDNN : Date Code

56 : Product Number
YMDNN : Date Code

L1

R1

R2

C

OUT

V

OUT

Table 1. Recommended Component Selection

V

(V) R1 (k) R2 (k) RT (k) L (H) C

OUT

OUT

(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

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Functional Pin Description

Pin No.

SOP-8

(Exposed Pad)

1 5 BOOT

2 6, 7 VIN
3 8, 9 SW Switch Node. Connect to external LC filter.

4, 9

(Exp osed Pa d)

5 1 FB

6 3 EN

7 2 PGOOD Power Good Output. The output of this pi n is open drain.
8 4 VCC Bias Supply.

WDFN -1 0L 3x3

10, 11

(Exposed Pad)

Pin Name Pin Funct ion

GND

RT8299

Boot strap fo r High Si de Ga te D river. Connect a 0.1F or grea ter
ceramic capacitor from BOO T to SW pin.

Supply I nput Voltage. Must bypass wit h a suitably large ceram ic
capacitor.

Ground. The exposed pad mu st be sol der ed t o a large PCB and
connected to GND for maximum power dissipation.

Feedback Input. This pin is connected to the conv erter output . It
is used to regula te the output of the conver t er to a desired value
via an inter nal res istive voltage divider . F or an adj ustable output,
an external resistive voltage divider is connected to t his pin.

Enable Input. A logic high enables the converter; a logic low
forces the RT8299 into shutdown mode, reducing the supply
current to less than 3A. Attach th is pin to VIN with a 100k pul l
up resistor for aut oma tic startup.

Function Block Diagram

VIN

Comparator

­+

2V

Reference

PGOOD

Generator

EN

VCC

FB

PGOOD

5k

3V

Regulator

300k

+

-

Error

Amplifier

30pF

1pF

Ramp

Generator

Oscillator

500kHz

+

-

PWM

Comparator

OC Limit
Clamp

Current Sense

Amplifier

Q

S

Driver

Q

R

­+

BOOT

SW

GND

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RT8299

Absolute Maximum Ratings (Note 1)

 Supply Input V oltage, V
 Switching Voltage, SW ------------------------------------------------------------------------------------ −0.6 to (V

---------------------------------------------------------------------------------- −0.3 to 26V

IN

+ 0.3V)

IN

< 20ns---------------------------------------------------------------------------------------------------------- −5V to 30V

 Boot V oltage, BOOT---------------------------------------------------------------------------------------- (V
 All Other Pins ------------------------------------------------------------------------------------------------ −0.3 to 6V
 Power Dissipation, P

@ TA = 25°C

D

− 0.3V) to (VSW + 6V)

SW

SOP-8 (Exposed Pad) ------------------------------------------------------------------------------------- 1.333W
W D FN-10L 3x3 ----------------------------------------------------------------------------------------------- 1.429W

 Package Thermal Re sistance (Note 2)

SOP-8 (Exposed Pad), θJA-------------------------------------------------------------------------------- 75°C/W
SOP-8 (Exposed Pad), θJC------------------------------------------------------------------------------- 15°C/W
W DFN-10L 3x3, θJA----------------------------------------------------------------------------------------- 70°C/W
WDFN-10L 3x3, θJC----------------------------------------------------------------------------------------- 8.2°C/W

 Lead T e mperature (Soldering, 10 sec.)----------------------------------------------------------------- 260°C
 Junction T e mperature -------------------------------------------------------------------------------------- 150°C
 Storage T emperature 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, V
 Junction T emperature Range------------------------------------------------------------------------------ − 40°C to 125°C
 Ambient T emperature Range------------------------------------------------------------------------------ 40°C to 85°C

----------------------------------------------------------------------------------------- 3V to 24V

IN

Electrical Characteristics

(VIN = 12V, T

Shutdown Current I
Sup pl y Cu rrent VEN = 3V, V
Upper Switch On Resistance
Lower Switch On Resistance -- 100 -- m
Switch Leakage VEN = 0V, VSW = 0V o r 12V -- 0 10 A
Current Limit I
Oscillator Frequency f
Short Circuit Frequency VFB = 0V -- 150 -- kHz
M axi m um D ut y C ycl e D
Minimum On-Time tON -- 100 -- ns
Feedback Voltage VFB 4.5V  VIN  24V 788 800 812 mV

EN Input
Threshold Voltage

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4

= 25°C, unless otherwise specified)

A

Parameter Symbol Test Conditions Min Typ Max Unit

V

SHDN

V

LIM

VFB = 0.75V 425 500 575 kHz

OSC

VFB = 0.8V -- 93 -- %

MAX

Logic-High V
Logic-Low V

©

2 -- 5.5

IH

-- -- 0.4

IL

= 0V -- -- 3 A

EN

= 1V -- 1 -- mA

FB

-- 100 -- m

VSW = 4.8V -- 5.5 -- A

BOOT

V

DS8299-04 October 2014www.richtek.com

RT8299

Parameter Symbol Test Conditions Min Typ Max Unit

Under Voltage Lockout
Threshold
Under Voltage Loc k out
Threshold Hysteresis

Power Good Threshold
VCC Regulator -- 5 -- V

VCC Load Regulation I
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. θ

Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.

is measured at T

JA

measured at the exposed pad of the package.

= 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is

A

VIN Rising -- 2.8 -- V

V

UVLO

V

-- 300 -- mV

UVLO

VOUT Rising, with Respect to V

-- 90 --

FB

VOUT Falling, with Respect to VFB -- 70 --

= 5mA 4 -- 4 %

CC

%

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