Richtek RT8202, RT8202A, RT8202B Datasheet

Single Synchronous Buck Controller

RT8202/A/B

General Description

The RT8202/A/B PWM controller provides high efficiency ,
excellent transient response, a nd high DC output a ccuracy
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 ha ndles wide
input/output voltage ratios with ea se and provides 100ns
“instant-on” response to load tran sients while maintaining
a relatively constant switching frequency .

The RT8202/A/B 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 MOSFET s. The buck conversion allows this device
to directly step down high-voltage batteries for the highest
possible efficiency . The RT8202/A/B is intended f or CPU
core, chipset, DRAM, or other low-voltage supplies as
low as 0.75V. RT8202 is available in WQFN-16L 4x4,
RT8202A is available in WQF N-16L 3x3 and R T8202B is
available in WQF N-14L 3.5x3.5 pack ages.

Ordering Information

RT8202/A/B

Features

zz

z Ultra-High Efficiency

zz

zz

z Resistor Progra mm able Current Li mit by Low-Side

zz

R

Sense (Lossless Limit) or Sense Resistor

DS(ON)

(High Accuracy)

zz

z Quick Load-Step Response within 100ns

zz

zz

z 1% V

zz

zz

z Adjustable 0.75V to 3.3V Output Range

zz

zz

z 4.5V to 26V Battery Input Range

zz

zz

z Resistor Programmable Frequency

zz

zz

z Over/Under Voltage Protection

zz

zz

z 2 Steps Current Limit During Soft-Start

zz

zz

z Drives Large Synchronous-Rectifier FET s

zz

zz

z Power-Good Indicator

zz

zz

z RoHS Compliant and 100% Lead (Pb)-Free

zz

Accuracy over Line and Load

OUT

Applications

z Notebook Computers
z CPU Core Supply
z Chipset/RAM Supply a s Low as 0.75V

Pin Configurations

(TOP VIEW)

Package Type
QW : WQ FN-16L 4x4 (W -Type) (RT8202)
QW : WQ FN-16L 3x3 (W -Type) (RT8202A)
QW : WQ FN-14L 3.5x3.5 (W-Type) (RT8202B)

Operating Temperature Range
P : Pb F re e with Commerc ia l Standa rd
G : Green (Halogen Free with Commer­ cial Standard)

Note :
Richtek Pb-free and Green products are :

` RoHS compliant and compatible with the current require-

VOUT

VDD

FB

PGOOD

WQFN-16L 4x4/WQFN-16L 3x3

TON

EN/DEM

BOOT

NC

13141516

UGATE

GND

17

8765

PGND

12
11

PHASE

10

OC
VDDP

9

LGATE

1
2

GND

3
4

NC

ments of IPC/JEDEC J-STD-020.

EN/DEM

GND

GND

15

BOOT

141

87

PGND

13
12
11

10

96

UGATE
PHASE
OC
VDDP

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

Marking Information

For marking information, contact our sales re presentative
directly or through a Richtek distributor located in your
area, otherwise visit our website for detail.

2

TON

3

VOUT

4

VDD

5

FB

PGOOD LGATE

WQFN-14L 3.5x3.5

DS8202/A/B-02 July 2008 www.richtek.com

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RT8202/A/B

p

yp

g

g

p

p

Typical Application Circuit

D

1

T

B

A

2

5

V

P

D

D

V

5

D

O

O

G

P

C

C

M

/

D

E

M

1

C

u

F

1

2

R

1

k

5

R

0

1

C
1

T

O

N

V

D

1

2

F

u

D

D

D

V

O

G

P
E

D

N

/
D

N

G
P

G

N

Functional Pin Description

Pin No.

RT8202/A RT8202B

1 3 VOUT

2 4 VDD

3 5 FB

4 6 PGOOD

5, 14 -- NC No Internal Connection.

6,

Exposed Pad

(1 7)

7,

Exposed Pad

(15)

7 8 PGND Power Groun d.

8 9 LGATE

9 10 VDDP

10 11 OC

11 12 PHASE

12 13 UGATE

13 14 BOOT

15 1 EN/DEM

16 2 TON

Pin Name Pin Function

GND

4

R

T

2

8

0

B

/

2

A

/

O

O

B

T

P

O

D

E

M

D

A

T

U

G

E

H

A

P

S

E

G

L

A

T

E

O

C

F

B

V

O

U

T

VOUT Sense Input. Connect to the output of PWM converter. VOUT is an

ut of the PWM controller.

in
Analog Supply Voltage Input for the internal analog integrated circuit.

ass to GND with a 1uF ceramic capacitor.

B
VOUT Feedback Input. Connect FB to a resistor voltage divider from
VOUT to GND to adjust the output from 0.75V to 3.3V.
Power Good Signal Open-Drain Output of PWM Converter. This pin will be
pulled high when the output voltage is within the target range.

Ground for Analog Circuitry. The exposed pad must be soldered to a large
PCB and connected to GND for maximum power dissipation.

Low-side N-MOSFET Gate-Drive Output for PWM. This pin swings
between GND and VDDP.
VDDP is the gate driver supply for the external MOSFETs. Bypass to GND
with a 1uF ceramic capacito r.
PW M Cur rent Lim it Settin g a nd sense . Co nnect a re sist or between OC to
PHASE for current limit settin
Inductor Connection. This pin is not only the zero-current-sense input for
the PWM converter, but also the UGATE hi
High-Side N-MOSFET Floating Gate-Driver Output for the PWM
converter. This
Boost Capacitor Connection for PWM Converter. Connect an external
ceramic ca

acitor to PHASE and an external diode to VDDP.
PW M Enable and Operati on Mode Selection Inpu t. Connect to VDD for
d iode- emu lati on mo de, connect t o GND fo r sh utdo wn m ode and float ing
the pin for CCM mode.
VIN Sense Input. Connect to VIN through a resistor. TON is an input of the
PWM controller.

V

I

N

V

4

5

.

6

o

2

t

V

R

3

1

M

C

R

4

2

.

2

C

3

0

1

.

u

F

R

5

0

1

0

k

R

6

A

O

Q
A

Q

2

7

4

0

2

4

1

0

u

F

1

O

4

7

2

0

L

1

2

4

.

u

H

R

7

R

C

5

C

8

0

1

.

u

F

8

1

2

k

R

9

2

0

k

.

h-side gate driver return.

in swings between PHASE and BOOT.

V

U

O

T

1

2

.

V

C

7

2

0

2

u

C

6

F

DS8202/A/B-02 July 2008www.richtek.com

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Function Block Diagram

TRIG

-

GM

+

On-time

Compute

1-SHOT

+

-

REF

+

-

+

-

SS Timer

VOUT

TON

FB

VDD

GND

SS(Internal)

115% V

70% V

0.75V V

REF

REF

OV

UV

90% V

­+

Latch

S1 Q

Latch

S1 Q

REF

Thermal

Shutdown

Comp

­+

Min. T

OFF

Q TRIG

1-SHOT

R

QS

Diode

Emulation

RT8202/A/B

BOOT

DRV

DRV

20uA

+

-

UGATE
PHASE

VDDP
LGATE

PGND

OC

EN/DEM

PGOOD

DS8202/A/B-02 July 2008 www.richtek.com

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RT8202/A/B

Absolute Maximum Ratings (Note 1)

z Input V oltage, TON to GN D ---------------------------------------------------------------------------------------------- −0.3V to 32V
z BOOT to GND -------------------------------------------------------------------------------------------------------------- −0.3V to 38V
z PHASE to BOOT ---------------------------------------------------------------------------------------------------------- −6V to 0.3V
z V DD, V DDP, VOUT , EN/DEM, FB, PGOOD to GN D -------------------------------------------------------------- −0.3V to 6V
z UGA TE to PHASE -------------------------------------------------------------------------------------------------------- −0.3V to 6V
z OC to GND ------------------------------------------------------------------------------------------------------------------ −0.3V to 32V
z LGA TE to GN D ------------------------------------------------------------------------------------------------------------- −0.3V to 6V
z PGND to GND -------------------------------------------------------------------------------------------------------------- −0.3V to 0.3V
z Power Dissipation, P

WQFN-16L 4x4 ------------------------------------------------------------------------------------------------------------ 1.852W
WQFN-16L 3x3 ------------------------------------------------------------------------------------------------------------ 1.471W
WQFN-14L 3.5x3.5 ------------------------------------------------------------------------------------------------------- 1.667W

z Package Thermal Re sistance (Note 4)

WQF N-16L 4x4, θJA------------------------------------------------------------------------------------------------------- 54°C/W
WQFN-16L 4x4, θJC------------------------------------------------------------------------------------------------------ 7°C/W
WQF N-16L 3x3, θJA------------------------------------------------------------------------------------------------------- 68°C/W
WQFN-16L 3x3, θJC------------------------------------------------------------------------------------------------------ 7.5°C/W
WQF N-14L 3.5x3.5, θJA-------------------------------------------------------------------------------------------------- 60°C/W
WQFN-14L 3.5x3.5, θJC------------------------------------------------------------------------------------------------- 7°C/W

z Lead Temperature (Soldering, 10 sec.)------------------------------------------------------------------------------- 260°C
z Junction T e mperature ---------------------------------------------------------------------------------------------------- 150 °C
z Storage T emperature Range -------------------------------------------------------------------------------------------- −65°C to 150°C
z ESD Susceptibility (Note 2)

HBM (Human Body Mode) ---------------------------------------------------------------------------------------------- 2kV
MM (Ma chine Mode)------------------------------------------------------------------------------------------------------ 200V

@ TA = 25°C

D

Recommended Operating Conditions (Note 3)

z Input Voltage, V
z Supply Voltage, V
z Junction T emperature Range--------------------------------------------------------------------------------------------
z Ambient T emperature Range--------------------------------------------------------------------------------------------

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

IN

, V

DD

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

DDP

−40°C to 125°C

−40°C to 85°C

Electrical Characteristics

(V

= V

DD

PWM Controller

Quiescent Supply C urrent VDD + VDDP, FB = 0.8V -- -- 1250 uA
TON Operating Current R

Shutdown Current I

4

DDP

= 5V, V

= 15V, V

IN

= 1.25V, EN/DEM = VDD, R

OUT

= 1MΩ, T

TON

= 25°C, unless otherwise specified)

A

Parameter Symbol Test Conditions Min Typ Max Units

= 1M -- 15 -- uA

TON

VDD + VDDP -- 1 10 uA

SHDN

TON -- 1 5 uA
EN/DEM = 0V −10 −1 -- uA

To be continued

DS8202/A/B-02 July 2008www.richtek.com

RT8202/A/B

Parameter Symbol Test Conditions Min Typ Max Units

FB Reference Voltage VFB V

= 4.5 to 5.5V 0.742 0.75 0.758 V

DD

FB Input Bias Current FB = 0.75V −1 0.1 1 uA
Output Voltage Range V
On-Time VIN = 15V, V

0.75 -- 3.3 V

OUT

= 1.25V, R

OUT

= 1M 267 334 401 ns

TON

Minimum Off-Time 250 400 550 ns
V

Shutdown Discharge

OUT

Resistance

EN/DEM = GND -- 20 -- Ω

Current Sensing

ILIM Source Current LGATE = High 18 20 22 uA
Current Comparator Offset GND − OC −10 -- 10 mV
Current Limit Setting Range R

2.5 -- 10 kΩ

ILIM

Zero Crossing Threshold GND − PHASE, EN/DEM = 5V −10 -- 5 mV

Faul t Protection

Current Limit Sense
Voltage

V

RILIM

GND − PHASE, R
GND − PHASE, R

= 2.5k 35 50 65 mV

ILIM

= 10k 170 200 230 mV

ILIM

Output UV Threshold 60 70 80 %
OVP Threshold

With respect to error comparator
threshold

10 15 20 %
OV Fault Delay FB forced above OV threshold -- 20 -- us
VDD UVLO Threshold

Soft-Start Ramp Time

Risi ng edge, Hyster e sis = 2 0m V,
PWM disabled below this level
From EN high to internal V

REF

reach

0.71V (0Æ95%)

4.1 4.3 4.5 V

-- 1.35 -- ms

UV Blank Time From EN signal going high -- 3.1 -- ms
Thermal Shutdown -- 155 -- °C

Thermal Shut down
Hysteresis

-- 10 -- °C

Driver On-Resistance

UGATE Driver Pull Up BOOT − PHASE = 5V -- 1.5 5 Ω
UGATE Driver Sink R

UGATEsk

BOOT − PHASE = 5V -- 1.5 5 Ω
LGATE Driver Pull Up LGATE, High State (Source) -- 1.5 5 Ω
LGATE Driver Pull Down LGATE, Low State (Sink) -- 0.6 2.5 Ω

UGATE Driver Source/Sink
Current
LGATE Dri ver So ur ce
Current

LGATE forced to 2.5V -- 1 -- A

UGATE − PHASE = 2.5V,
BOOT − PHASE = 5V

-- 1 -- A

LGATE Driver Sink Current LGATE forced to 2.5V -- 3 -- A

LGATE Rising (P HA SE = 1.5V ) -- 30 - -

Dead Time

ns

UGATE Rising -- 30 --

To be continued

DS8202/A/B-02 July 2008 www.richtek.com

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RT8202/A/B

Parameter Symbol Test Conditions Min Typ Max Units

Logic I/O

EN/DEM Logic Low Voltage -- -- 0.8 V
EN/DEM Logic High Voltage
EN/DEM Floating Voltage EN/DEM Open -- 2 -- V

Logic Input Current

PGOOD (upper side threshold decide by OV threshold)

Trip Threshold (Falling)

Fault Propagation Delay
Output Low Voltage I

Leakage Current High state, forced to 5.0V -- -- 1 uA

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

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

2.9 -- -- V

EN/DEM = V
EN/DEM = 0 −5 −1 --

-- 1 5

DD

uA

Measured at FB, with respect to
reference, no load.

−13 −10 −7 %

Hysteresis = 3%
Fal ling edge , FB f or ce d b elo w

PGOOD trip threshold

= 1mA -- -- 0.4 V

SINK

is on the expose pad for the WQFN package.

JC

-- 2.5 -- us

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