Richtek RT8209A, RT8209B, RT8209C Datasheet

Single Synchronous Buck Controller

RT8209A/B/C

General Description

The RT8209A/B/C PWM controller provides high efficiency,

excellent transient response, and high DC output accuracy

needed for stepping down high voltage batteries to

generate low voltage CPU core, I/O, and chipset RAM

supplies in notebook computers.

The constant-on-time PWM control scheme handles wide

input/output voltage ratios with ease and provides 100ns

“instant-on” response to load transients while maintaining

a relatively constant switching frequency.

The RT8209A/B/C achieves high efficiency at a reduced

cost by eliminating the current-sense resistor found in

traditional current mode PWMs. Efficiency is further

enhanced by its ability to drive very large synchronous

rectifier MOSFETs. The buck conversion allows this device

to directly step down high voltage batteries for the highest

possible efficiency. The RT8209A/B/C is intended for CPU

core, chipset, DRAM, or other low voltage supplies as

low as 0.75V. The RT8209A is in a WQFN-16L 3x3

package, the RT8209B is in a WQFN-14L 3.5x3.5 package

and the RT8209C is available in a TSSOP-14 package.

Ordering Information

RT8209

Package Type
QW : WQFN-16L 3x3 (W-Type)
QW : WQFN-14L 3.5x3.5 (W-Type)
C : TSSOP-14

Operating Temperature Range
G : Green (Halogen Free with Commer­ cial Standard)

A : WQFN-16L 3x3
B : WQFN-14L 3.5x3.5
C : TSSOP-14

Features

zz

Ultra-High Efficiency

z

zz

zz

z Resistor Programmable Current Limit by Low Side

zz

R

zz

z Quick Load Step Response within 100ns

zz

zz

z 1% V

zz

zz

z 4.5V to 26V Battery Input Range

zz

zz

z Resistor Programmable Frequency

zz

zz

z Integrated Bootstrap Switch

zz

zz

z Integrated Negative Current Limiter

zz

zz

z Over/Under Voltage Protection

zz

zz

z 4 Steps Current Limit During Soft-Start

zz

zz

z Power Good Indicator

zz

zz

z RoHS Compliant and Halogen Free

zz

Sense (Lossless Limit)

DS(ON)

Accuracy over Line and Load

FB

Applications

z Notebook Computers

z System Power Supplies

z I/O Supplies

Marking Information

For marking information, contact our sales representative

directly or through a Richtek distributor located in your

area, otherwise visit our website for detail.

Note :

Richtek Green 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.

DS8209A/B/C-03 April 2010 www.richtek.com

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RT8209A/B/C

Pin Configurations

TON

EN/DEM

BOOT

NC

13141516

NC

GND

12

UGATE

11

PHASE

10

CS

17

9

VDDP

8765

PGND

LGATE

R

2

R

T

8

2

O

N

T

D

V

D

P

1

R

0

1

2

R

0

1

0

k

2

C

1

µ

F

R

1

8

D

D

V

O

O

D

G

P

C

S

6

k

1

VOUT

2

VDD

3

FB

PGOOD

4

NC

RT8209A (WQFN-16L 3x3)

Typical Application Circuit

P

D

D

V

D

P

O

O

G

(TOP VIEW)

EN/DEM

BOOT

141

NC

R

R

13

UGATE

12

PHASE

11

CS

15

10

VDDP

96

87

PGND

4

0

C

5

0

3

µ

F

1

0

.

C

1

B

S

1

0

9

3

N

2

TON

3

VOUT

4

VDD

5

FB

PGOOD LGATE

GND

RT8209B (WQFN-14L 3.5x3.5)

T

O

N

5

k

0

0

9

A

C

/

B

/

O

B

O

T

U

T

E

G

A

P

S

E

H

A

A

L

G

T

E

N

D

P

G

F

B

14

EN/DEM

TON

VOUT

VDD

FB

PGOOD

GND

2

3

4

5

6

7

BOOT

13

UGATE

12

PHASE

11

CS

10

VDDP

9

LGATE

8

PGND

RT8209C (TSSOP-14)

V

I

N

5

.

4

o

t

2

V

6

V

C

4

1

µ

F

0

1

Q

B

S

C

1

1

L

9

1

1

µ

N

0

3

S

S

Q

2

H

7

*

R

C

7

*

*

R

8

1

2

k

R

9

3

0

k

V

1

.

=

0

V

O

p

t

O

:

o

a

i

n

l

*

C

5

C

6

*

5

U

T

C

1

2

2

0

µ

F

/

E

D

C

M

M

C

EN/DEM

G

Functional Pin Description

Pin No.

RT8209A RT8209B/C

1 3 VOUT

2 4 VDD

3 5 FB

4 6 PGOOD

5, 14

17 (Exposed pad)

RT 8209B :

15 (Exposed pa d)

O

U

V

T

D

N

Pin Name Pin Function

Outpu t Vo lta ge Pin. Conne ct to the o utpu t of PWM converter.
VOUT is an inpu t of the PW M cont roller.

Analog sup ply voltage input for the interna l anal og inte grated
circuit. Bypass to GND with a 1 μF ceramic c apacitor.

Feed back In put Pin. C onnect FB to a resistor voltage divider
from VOUT to GND to adjust VOUT from 0.7 5V to 3. 3V
Power goo d s ignal open-drain output of PWM converte r. This
pin will be pulled h igh when the output voltage is within the
targe t range.
No interna l connecti on. The e xposed pad must b e soldered to

NC

a large PCB and conne cted to GND for maximum power
dissipation.

To be continued

DS8209A/B/C-03 April 2010www.richtek.com

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RT8209A/B/C

Pin No.

Pin Na me Pin Function

RT8209A RT8209B/C

6 7 GND Analog Ground.

7 8 PGND Power Ground.

8 9 LGATE

9 10 VDDP

Low side N-MOSFET gate driver output for PWM. This pin
swings between GND and VDDP.

VDDP is the gate driver supply for external MOSFETs. Bypass
to GND wi th a 1μF ceramic capacitor.

Over Current Trip Point Set Input. Connect resistor from this

10 1 1 CS

pin to signal ground to set threshold for both over current and
negative over current limit.

11 12 PHASE

12 1 3 UGAT E

13 1 4 BOOT

The UGATE High Side Gate Driver Ret urn. Also serves as
anode of over current comparator.

High side N-MOSFET floating gate driver output for the PWM
converter. This pin swings between PHASE and BOOT.

Bootstrap Capacitor Connection for PWM Converter. Connect
to an external ceramic capacitor to PHASE.
Enable/Diode Emulation Mode Control Input. Connect to VDD

15 1 EN/D EM

for diode-emulation mode, connect to GND for shutdown and
floating the pin for CCM mode.

16 2 TON

On Time/Frequency Adjustment Pin. Connect to PHASE
through a resistor. TON is an input for the PWM controller.

Function Block Diagram

TRIG

-

GM

+

On-time

Compute

1-SHOT

+

-

+

-

+

-

SS Timer

VOUT

TON

FB

VDD

EN/DEM

SS

(internal)

V

REF

125% V

70% V

REF

REF

OV

UV

90% V

­+

Latch

S1 Q

Latch

S1 Q

REF

Thermal

Shutdown

BOOT

R

QS

Min. T

OFF

QTRIG

1-SHOT

­+

Diode

Emulation

+

-

-

+

GM

DRV

DRV

10µA

UGATE

PHASE

VDDP

LGATE

PGND

PGOOD

CS

GND

DS8209A/B/C-03 April 2010 www.richtek.com

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RT8209A/B/C

Absolute Maximum Ratings (Note 1)

z VDD, VDDP, VOUT, EN/DEM, FB, PGOOD, TON to GND------------------------------------------------------- −0.3V to 6V
z BOOT to GND -------------------------------------------------------------------------------------------------------------- −0.3V to 38V

z BOOT to PHASE ---------------------------------------------------------------------------------------------------------- −0.3V to 6V

z PHASE to GND

DC----------------------------------------------------------------------------------------------------------------------------- –0.3V to 32V

< 20ns ----------------------------------------------------------------------------------------------------------------------- −8V to 38V

z UGATE to PHASE

DC----------------------------------------------------------------------------------------------------------------------------- −0.3V to 6V

< 20ns ----------------------------------------------------------------------------------------------------------------------- −5V to 7.5V

z CS to GND ------------------------------------------------------------------------------------------------------------------ −0.3V to 6V

z LGATE to GND ------------------------------------------------------------------------------------------------------------- −0.3V to 6V

z LGATE to GND

DC----------------------------------------------------------------------------------------------------------------------------- −0.3V to 6V

< 20ns ----------------------------------------------------------------------------------------------------------------------- −2.5V to 7.5V

z PGND to GND -------------------------------------------------------------------------------------------------------------- –0.3V to 0.3V

z Power Dissipation, P

D

WQFN−16L 3x3 ------------------------------------------------------------------------------------------------------------ 1.471W

WQFN−14L 3.5x3.5 ------------------------------------------------------------------------------------------------------- 1.667W

TSSOP-14 ------------------------------------------------------------------------------------------------------------------- 0.741W

z Package Thermal Resistance (Note 2)

WQFN−16L 3x3, θJA------------------------------------------------------------------------------------------------------ 68°C/W

WQFN−16L 3x3, θJC------------------------------------------------------------------------------------------------------ 7.5°C/W

WQFN−14L 3.5x3.5, θJA------------------------------------------------------------------------------------------------- 60°C/W

WQFN−14L 3.5x3.5, θJC------------------------------------------------------------------------------------------------- 7.5°C/W

TSSOP-14, θJA------------------------------------------------------------------------------------------------------------- 135°C/W

z Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------- 260°C

z Junction Temperature ----------------------------------------------------------------------------------------------------- 150°C
z Storage Temperature Range -------------------------------------------------------------------------------------------- −65°C to 150°C

z ESD Susceptibility (Note 3)

HBM (Human Body Mode) ---------------------------------------------------------------------------------------------- 2kV

MM (Machine Mode) ------------------------------------------------------------------------------------------------------ 200V

@ T

= 25°C

A

Recommended Operating Conditions (Note 4)

z Input Voltage, V

z Supply Voltage, V

z Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C

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

4

---------------------------------------------------------------------------------------------------------- 4.5V to 26V

IN

, V

DD

---------------------------------------------------------------------------------------------- 4.5V to 5.5V

DDP

−40°C to 85°C

DS8209A/B/C-03 April 2010www.richtek.com

RT8209A/B/C

Electrical Characteristics

(V

= 15V, V

IN

PWM Controller

Quiescent Supply Current

Shutdown Current

FB Reference Voltage V
FB Input Bias Current VFB = 0.75V −1 0.1 1 μA
Output Voltage Range V

On Time

Minimum Off-Time 250 400 550 ns
VOUT Shutdown Discharge

Resistance

Current Sensing

Current Limiter Source Current CS to GND 9 10 11 μA
Curr en t C omparat or O ffset −10 -- 10 mV
Zer o Cr ossing Thr eshold PH AS E to GND , EN /D EM = 5V −10 -- 5 mV

Fa ul t Protection

Current Limit Threshold

Current Limit Setting Range CS to GND 50 -- 200 mV
Output UV Threshold UVP detect 60 70 80 %
OVP Threshold V
OV Fault Delay FB forced above OV threshold -- 20 -- μs

Threshold

Current Limit Step Duration at
Soft Start
UVP Blanking Time From EN signal going high -- 512 -- clks

Thermal Shutdown T

Driver On-Resista nce

= V

DD

= 5V, TA = 25°C, unless otherwise specified)

DDP

Parameter Symbol Test Conditions Min Typ Max Unit

I

V

VDD

I

V

VDDP

I

SHDN_VDD

I

SHDN_VDDP

REF

OUT

EN/DEM = 0V -- 1 10 μA

V

0.75 -- 3.3 V

= 0.8V, EN/DEM = 5V -- 500 800 μA

FB

= 0.8V, EN/DEM = 5V -- 1 10 μA

FB

EN/DEM = 0V -- -- 1 μA

= 4.5V to 5.5V 0.742 0.750 0.758 V

DD

V

PHASE

R

TON

= 12V, V

= 250kΩ

OUT

= 2.5V,

336 420 504 ns

EN/DEM = GND -- 20 -- Ω

GND − PHASE, VCS = 50mV 40 50 60 mV
GND − PHASE, V

FB_OVP

OVP detect 120 125 130 %

Rising edge, PWM disabled below
this level

= 200mV 190 200 210 mV

CS

4.1 4.3 4.5 V VDD Under Voltage Lockout

Hysteresis -- 80 -- mV

Each step -- 128 -- clks

Hysteresis = 10°C -- 155 -- °C

SHDN

UGATE Driver Pull-up V

UGATE Driver Sink V

BOOT

BOOT

− V

− V

= 5V -- 2 5 Ω

PHASE

= 5V -- 1 5 Ω

PHASE

LGATE Driver Pull-up LGATE, High State (Source) -- 1 5 Ω
LGATE Driver Pull-down LGATE, Low State (Sink) -- 0.5 2.5 Ω

UGATE Driver Source/Sink
Curr ent

LGATE Driver Source Current V

LGATE Driver Sink Current V

LGATE Rising (V

Dead Time

V

UGATE

V

BOOT

LGATE

LGATE

− V

− V

PHASE

PHASE

= 2.5V,

= 5V

-- 1 -- A

= 2.5V -- 1 -- A

= 2.5V -- 3 -- A

= 1.5V) -- 30 - - ns

PHASE

UGATE Rising -- 30 - - ns

To be continued

DS8209A/B/C-03 April 2010 www.richtek.com

5

RT8209A/B/C

Parameter Symbol Test Conditions Min Typ Max Unit

Internal BOOT Charging S witch
On Resistance

Logic I/O

EN/DEM Logic Input Voltage

Logic Input Current

PGOOD

PGOOD Th reshold

Fa ult Propag ation Delay

Out put Low Voltage I
Leakage Current High state, forced to 5V -- -- 1 μA

VDD P to BOOT, 10mA -- -- 80 Ω

EN/DEM Low -- -- 0.8 V

EN/DEM High 2.9 -- -- V

EN/DEM float -- 2 -- V

EN /DEM = VDD -- 1 5

μA

EN/DEM = 0 −5 1 --

with respect to referen ce,

V

FB

PGOOD from Low t o High
V

with respect to reference,

FB

PGOOD from High to Low

87 90 93 %

-- 125 -- %

Hysteresis -- 3 -- %

Fallin g ed ge, FB forced below
PGOOD trip threshold

= 1mA -- -- 0.4 V

SINK

-- 20 -- μs

Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for

stress ratings. 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 for extended

periods may remain possibility to 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 in the natural convection at TA = 25°C on a high effective four layers thermal conductivity test board of

JA

JEDEC 51-7 thermal measurement standard. The case point of θ

is on the expose pad for the WQFN package.

JC

DS8209A/B/C-03 April 2010www.richtek.com

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