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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 |
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8 |
VCC |
VIN |
2 |
GND |
7 |
PGOOD |
SW |
3 |
6 |
EN |
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GND |
4 |
9 |
5 |
FB |
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SOP-8 (Exposed Pad)
FB 1
PGOOD 2 EN 3
VCC 4
BOOT 5
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10 |
GND |
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GND |
9 |
SW |
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8 |
SW |
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7 |
VIN |
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11 6 |
VIN |
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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 |
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RT8299
Marking Information
RT8299GSP |
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RT8299GQW |
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RT8299 |
RT8299GSP : Product Number |
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56= : Product Number |
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YMDNN : Date Code |
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56=YM |
YMDNN : Date Code |
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GSPYMDNN |
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DNN |
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RT8299ZSP |
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RT8299ZQW |
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RT8299ZSP : Product Number |
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56 : Product Number |
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RT8299 |
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YMDNN : Date Code |
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56 YM |
YMDNN : Date Code |
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ZSPYMDNN |
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DNN |
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Typical Application Circuit |
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RT8299 |
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VIN |
CIN |
VIN |
BOOT |
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10µF x 2 |
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CBOOT |
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Chip Enable |
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SW |
L1 |
VOUT |
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EN |
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RT |
R1 |
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VCC |
FB |
COUT |
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CVCC |
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R2 |
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1µF |
GND |
PGODD |
Power Good |
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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 |
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RT8299
Functional Pin Description
Pin No. |
Pin Name |
Pin Function |
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SOP-8 |
WDFN-10L 3x3 |
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(Exposed Pad) |
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1 |
5 |
BOOT |
Bootstrap for High Side Gate Driver. Connect a 0.1 F or greater |
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ceramic capacitor from BOOT to SW pin. |
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2 |
6, 7 |
VIN |
Supply Input Voltage. Must bypass with a suitably large ceramic |
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capacitor. |
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3 |
8, 9 |
SW |
Switch Node. Connect to external LC filter. |
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4, 9 |
10, 11 |
GND |
Ground. The exposed pad must be soldered to a large PCB and |
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(Exposed Pad) |
(Exposed Pad) |
connected to GND for maximum power dissipation. |
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Feedback Input. This pin is connected to the converter output. It |
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5 |
1 |
FB |
is used to regulate the output of the converter to a desired value |
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via an internal resistive voltage divider. For an adjustable output, |
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an external resistive voltage divider is connected to this pin. |
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Enable Input. A logic high enables the converter; a logic low |
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6 |
3 |
EN |
forces the RT8299 into shutdown mode, reducing the supply |
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current to less than 3 A. Attach this pin to VIN with a 100k pull |
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up resistor for automatic startup. |
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7 |
2 |
PGOOD |
Power Good Output. The output of this pin is open drain. |
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8 |
4 |
VCC |
Bias Supply. |
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Function Block Diagram
VIN |
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Current Sense |
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Ramp |
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Amplifier |
- |
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5k |
Comparator |
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Generator |
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+ |
EN |
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- |
Regulator |
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BOOT |
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3V |
+ |
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Oscillator |
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2V |
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S |
Q |
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VCC |
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500kHz |
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Driver |
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+ |
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Reference |
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R |
Q |
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+ |
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-PWM |
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FB |
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- |
Error |
Comparator |
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SW |
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Amplifier |
OC Limit |
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300k |
30pF |
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PGOOD |
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PGOOD |
Clamp |
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Generator |
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1pF |
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GND |
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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 |
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SOP-8 (Exposed Pad) ------------------------------------------------------------------------------------- |
1.333W |
WDFN-10L 3x3 ----------------------------------------------------------------------------------------------- |
1.429W |
Package Thermal Resistance (Note 2) |
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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) |
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HBM (Human Body Model) --------------------------------------------------------------------------------- |
2kV |
MM (Machine Model) ---------------------------------------------------------------------------------------- |
200V |
Recommended Operating Conditions |
(Note 4) |
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Supply Voltage, VIN |
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3V to 24V |
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Junction Temperature Range ------------------------------------------------------------------------------ |
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−40°C to 125°C |
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Ambient Temperature Range ------------------------------------------------------------------------------ |
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40°C to 85°C |
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Electrical Characteristics |
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(VIN = 12V, TA = 25°C, unless otherwise specified) |
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Parameter |
Symbol |
Test Conditions |
Min |
Typ |
Max |
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Unit |
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Shutdown Current |
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ISHDN |
VEN = 0V |
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-- |
-- |
3 |
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A |
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Supply Current |
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VEN = 3V, VFB = 1V |
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1 |
-- |
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mA |
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Upper Switch On Resistance |
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-- |
100 |
-- |
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m |
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Lower Switch On Resistance |
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-- |
100 |
-- |
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m |
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Switch Leakage |
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VEN = 0V, VSW = 0V or 12V |
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0 |
10 |
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A |
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Current Limit |
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ILIM |
VBOOT VSW = 4.8V |
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5.5 |
-- |
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A |
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Oscillator Frequency |
fOSC |
VFB = 0.75V |
425 |
500 |
575 |
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kHz |
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Short Circuit Frequency |
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VFB = 0V |
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-- |
150 |
-- |
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kHz |
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Maximum Duty Cycle |
DMAX |
VFB = 0.8V |
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93 |
-- |
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% |
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Minimum On-Time |
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tON |
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-- |
100 |
-- |
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Feedback Voltage |
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VFB |
4.5V VIN 24V |
788 |
800 |
812 |
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mV |
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EN Input |
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Logic-High |
VIH |
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2 |
-- |
5.5 |
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V |
Threshold Voltage |
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Logic-Low |
VIL |
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-- |
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0.4 |
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Copyright ©2014 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
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www.richtek.com |
DS8299-04 October 2014 |
4 |
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RT8299
Parameter |
Symbol |
Test Conditions |
Min |
Typ |
Max |
Unit |
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Under Voltage Lockout |
VUVLO |
VIN Rising |
-- |
2.8 |
-- |
V |
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Threshold |
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Under Voltage Lockout |
VUVLO |
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-- |
300 |
-- |
mV |
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Threshold Hysteresis |
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Power Good Threshold |
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VOUT Rising, with Respect to VFB |
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90 |
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% |
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VOUT Falling, with Respect to VFB |
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70 |
-- |
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VCC Regulator |
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-- |
5 |
-- |
V |
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VCC Load Regulation |
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ICC = 5mA |
4 |
-- |
4 |
% |
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Soft-Start Period |
tSS |
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-- |
2 |
-- |
ms |
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Thermal Shutdown |
TSD |
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-- |
150 |
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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 |
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