Richtek RT8204LGQW, RT8204LZQW Schematic [ru]

RT8204L

Single Synchronous Buck Controller

General Description

The RT8204L 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 RT8204L 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 RT8204L is intended for CPU core, chipset, DRAM, or other low voltage supplies as low as 0.75V. The RT8204L is available in a WQFN-16L 3x3 package.

A built in LDO controller can drive an external N-MOSFET to provide a second output voltage from PWM output or other power source. The RT8204L can provide adjustable voltage down to 0.75V and maximum output voltage is dependen on the selected MOSFET. The internal 0.75V reference voltage with ±1.5% accuracy provides tight regulation of the output voltage. Other features such as independent enable control, open drain power good indicator, under voltage protection, and soft start make the RT8204L a system friendly power management solution for various applications.

Features

zPWM Controller

`Ultra High Efficiency

`Resistor Programmable Current Limit by Low Side RDS(ON) Sense (Lossless Limit)

`4700ppm/°C RDS(ON) Current Sensing

`Quick Load Step Response within 100ns

`1% VFB Accuracy Over Line and Load

`Adjustable 0.75V to 3.3V Output Range

`4.5V to 26V Battery Input Range

`Resistor Programmable Frequency

`Integrated Bootstrap Switch

`Over/Under Voltage Protection

`Voltage Ramp Soft-Start

`Power Good Indicator

zLDO Controller

`1.5% accuracy Over Line and Load

`Independent Enable and Power Good Indicator

`Drive N-MOSFETs within Rail to Rail Controller Voltage

`MLCC and POSCAP Stable

zRoHS Compliant and Halogen Free

Applications

zNotebook Computers

zCPU Core Supply

zChipset/RAM Supply as Low as 0.75V

Ordering Information

RT8204L

Package Type

QW : WQFN-16L 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.

DS8204L-04 April 2011

www.richtek.com

 

1

RT8204L

Marking Information

Pin Configurations

RT8204LGQW

(TOP VIEW)

J8= : Product Code

TON

EN/DEM

LEN

BOOT

 

J8=YM

 

 

YMDNN : Data Code

 

 

 

 

 

DNN

 

16

15

14

13

 

 

 

 

 

VOUT

1

 

 

12

UGATE

 

VDD

2

GND

11

PHASE

 

FB

3

10

OC

 

 

 

 

PGOOD

 

 

17

VDDP

 

4

 

 

9

RT8204LZQW

 

5

6

7

8

 

 

LPGOOD

LFB

LDRV

LGATE

 

J8

: Product Code

 

 

 

 

 

 

YMDNN : Data Code

 

 

 

 

 

J8 YM

 

 

 

 

 

 

DNN

 

WQFN-16L 3x3

 

Typical Application Circuit

VIN 4.5V to 26V

RTON

 

 

16

VDDP

 

9

5V

R2

 

C1

 

R1

2

 

 

 

C2

 

PGOOD

 

4

CCM/DEM

 

15

 

 

LDO Enable

 

14

 

 

LDO PGOOD

 

5

 

 

R3

 

V

 

 

DDP

 

 

17 (Exposed Pad)

* :

Optional

 

RT8204L

 

R4

 

 

 

C4

 

 

 

13

 

 

 

 

 

 

 

TON

BOOT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C3

 

 

 

 

 

V

 

 

 

 

 

 

 

 

 

VDDP

 

12

R5

 

 

 

 

 

OUT1

UGATE

 

 

Q1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

L1

 

 

 

PHASE

11

 

 

 

 

 

 

 

VDD

 

 

 

 

 

 

 

 

LGATE

8

 

 

 

 

R6*

 

 

C8

 

 

 

Q2

 

 

 

 

 

R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OC

10

ILIM

 

 

 

C5*

R7

C6*

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PGOOD

FB

3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

EN/DEM

 

 

 

 

 

 

 

R8

 

C7*

LEN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LPGOOD

VOUT

1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LDRV

7

 

 

 

Q3

 

 

 

C14

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R9

R10

 

 

 

 

V

OUT2

 

 

 

 

R11

 

 

 

GND

 

 

C10

 

C11*

C12

C13

 

 

 

 

 

 

 

 

 

6

 

 

 

 

 

LFB

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R12

 

 

 

 

 

 

 

C9

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

www.richtek.com

DS8204L-04 April 2011

2

 

Richtek RT8204LGQW, RT8204LZQW Schematic

RT8204L

Function Block Diagram

 

 

TRIG

 

 

 

 

 

 

 

VOUT

 

On-time

 

 

 

 

 

 

 

Compute

 

 

 

 

 

 

TON

 

 

 

 

 

 

 

 

1-SHOT

 

 

R

 

 

 

 

 

 

 

 

 

 

 

 

+

 

 

- Comp

 

 

BOOT

SS (Internal)

+

 

 

 

 

 

 

 

 

 

 

 

 

GM

 

 

+

S

Q

DRV

UGATE

 

-

-

 

 

 

 

 

 

 

 

 

 

 

PHASE

 

 

 

 

 

 

Min. TOFF

 

 

 

 

 

 

 

 

Q

TRIG

 

 

 

 

 

+

OV

Latch

1-SHOT

 

 

VDDP

115% VREF

S1

Q

 

 

DRV

LGATE

-

 

Latch

 

 

FB

 

+

UV

 

 

 

PGND

 

S1

Q

 

Diode

 

 

70% VREF

 

-

 

 

 

 

 

 

 

 

 

-

 

Emulation

 

 

 

 

 

 

 

 

 

 

 

 

 

90% VREF

 

 

 

 

 

 

 

+

 

 

20µA

 

 

 

SS Ramp

Thermal

 

 

 

VDD

 

 

 

+

OC

 

 

 

 

Shutdown

 

 

GND

 

 

 

 

 

 

 

-

 

 

 

EN/DEM

 

 

PGOOD

 

 

 

 

 

LEN

 

 

SS

 

 

 

 

0.75V VREF

+

X1

LDRV

SS Ramp

-

 

 

LPGOOD

 

 

 

LFB

-

 

 

90% VREF

+

 

 

50% VREF

-

 

 

+

 

 

LDO Controller

DS8204L-04 April 2011

www.richtek.com

3

RT8204L

Functional Pin Description

Pin No.

Pin Name

Pin Function

1

VOUT

Output Voltage Sense Pin. Connect this pin to the output of the PWM converter.

VOUT is an input of the PWM controller.

 

 

2

VDD

Analog Supply Voltage Input for Internal Analog Integrated Circuit. Bypass this

pin to GND with a 1μF ceramic capacitor.

 

 

3

FB

Feedback Input of PWM Controller. Connect FB to a resistive voltage divider

from VOUT to GND to adjust the output voltage from 0.75V to 3.3V.

 

 

4

PGOOD

Power Good Signal Open-Drain Output of PWM Controller. This pin will be

pulled high when the output voltage is within the target range.

 

 

5

LPGOOD

Power Good Signal Open-Drain Output of the LDO Regulator. This pin will be

pulled high when the output voltage is within the target range.

 

 

6

LFB

Feedback Input of LDO Regulator. This pin will be pulled high when the output

voltage is within the target range.

 

 

7

LDRV

Drive Signal for LDO’s Path MOSFET.

8

LGATE

Low Side N-MOSFET Gate-Drive Output for the PWM Controller. This pin

swings between GND to VDDP.

 

 

9

VDDP

Gate Driver Supply for external MOSFETs. Bypass this pin to GND with a 1μF

ceramic capacitor.

 

 

10

OC

PWM Current Limit Setting and Sense. Connect a resistor between OC to

PHASE for current limit setting.

 

 

11

PHASE

Inductor Connection. This pin is not only the zero current sense input for the

PWM converter, but also the UGATE high side gate driver return.

 

 

12

UGATE

High Side N-MOSFET Floating Gate-Driver Output for PWM Controller. This pin

swings between PHASE and BOOT.

 

 

13

BOOT

Boost Capacitor Connection for PWM Controller. Connect an external ceramic

capacitor from this pin to PHASE.

 

 

 

 

LDO Enable Input with Internal Pull Low Resistor. LDO is enabled if LEN voltage

14

LEN

is greater than the Logic High voltage level and disabled if LEN voltage is less

 

 

than the Logic Low voltage level.

 

 

PWM Enable and Operation Mode Selection Input. Connect to VDD for diode

15

EN/DEM

emulation mode, connect GND for shutdown mode, and float the pin for CCM

 

 

mode.

16

TON

On Time/Frequency Adjustment Pin. Connect this pin to VIN through a resistor.

TON is an input of the PWM controller.

 

 

17 (Exposed Pad)

GND

Analog Ground and Power Ground. The exposed pad must be soldered to a

large PCB and connected to GND for maximum power dissipation.

 

 

www.richtek.com

DS8204L-04 April 2011

4

 

 

 

 

 

 

 

RT8204L

Absolute Maximum Ratings

(Note 1)

 

 

 

 

 

 

z Input Voltage, TON to GND ------------------------------------------------------------------------------------------------

 

 

 

 

 

–0.3V to 32V

z BOOT to PHASE ------------------------------------------------------------------------------------------------------------

 

 

 

 

 

–0.3V to 6V

z UGATE to PHASE

 

 

 

 

 

 

 

 

 

DC -------------------------------------------------------------------------------------------------------------------------------

 

 

 

 

 

–0.3V to 6V

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

 

 

 

 

 

−5V to 7.5V

z LGATE to GND

 

 

 

 

 

 

 

 

 

DC -------------------------------------------------------------------------------------------------------------------------------

 

 

 

 

 

–0.3V to 6V

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

 

 

 

 

 

−2.5V to 7.5V

z PHASE to GND

 

 

 

 

 

 

 

 

 

DC -------------------------------------------------------------------------------------------------------------------------------

 

 

 

 

 

–0.3V to 32V

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

 

 

 

 

 

−8V to 38V

z VDD, VDDP, VOUT, EN/DEM, LEN, LFB, FB, PGOOD, LPGOOD, LDRV to GND -------------------------

 

 

–0.3V to 6V

z OC to GND --------------------------------------------------------------------------------------------------------------------

 

 

 

 

 

–0.3V to 28V

z Power Dissipation, PD @ TA = 25°C

 

 

 

 

 

 

 

WQFN-16L 3x3 --------------------------------------------------------------------------------------------------------------

 

 

 

 

 

1.471W

 

 

z Package Thermal Resistance (Note 2)

 

 

 

 

 

 

 

WQFN-16L 3x3, θJA ---------------------------------------------------------------------------------------------------------

 

 

 

 

 

68°C/W

 

 

WQFN-16L 3x3, θJC --------------------------------------------------------------------------------------------------------

 

 

 

 

 

7.5°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

 

 

Recommended Operating Conditions (Note 4)

 

 

 

 

 

 

z Input Voltage, VIN ------------------------------------------------------------------------------------------------------------

 

 

 

 

 

4.5V to 26V

z Supply Voltage, VDD, VDDP ------------------------------------------------------------------------------------------------

 

 

 

 

 

4.5V to 5.5V

z Junction Temperature Range

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

 

 

 

 

40°C to 125°C

z Ambient Temperature Range

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

 

 

 

 

40°C to 85°C

Electrical Characteristics

 

 

 

 

 

 

 

(VDD = VDDP = 5V, VIN = 15V, VEN/DEM = VDD, RTON = 1MΩ, TA = 25°C, unless otherwise specified)

 

 

 

 

 

Parameter

 

Symbol

 

Test Conditions

Min

Typ

Max

 

Unit

 

PWM Controller

 

 

 

 

 

 

 

 

 

Quiescent Current

 

IQ

 

VDD + VDDP, VFB = 0.8V, forced above

--

--

1250

 

μA

 

 

 

the regulation point

 

 

 

 

 

 

 

 

 

 

 

 

TON Operating Current

 

 

 

 

--

15

--

 

μA

 

 

 

 

 

VDD + VDDP

--

1

10

 

 

 

Shutdown Current

 

ISHDN

 

TON

--

1

5

 

μA

 

 

 

 

 

VEN/DEM = 0V

−10

−1

--

 

 

 

FB Reference Voltage

 

VFB

 

VDD = 4.5V to 5.5V

0.742

0.75

0.758

 

V

 

 

 

 

 

 

 

 

To be continued

 

 

 

 

 

 

 

 

 

 

DS8204L-04 April 2011

 

 

 

 

 

www.richtek.com

 

 

 

 

 

 

 

 

 

5

RT8204L

Parameter

Symbol

Test Conditions

Min

Typ

Max

Unit

FB Input Bias Current

 

VFB = 0.75V

−1

0.1

1

μA

Output Voltage Range

VOUT

 

0.75

--

3.3

V

On-Time

 

 

VIN = 15V, VOUT = 1.25V,

267

334

401

ns

 

 

 

RTON = 1MΩ

 

 

 

 

Minimum Off-Time

 

 

 

250

400

550

ns

 

 

 

 

 

 

 

 

VOUT Shutdown Discharge

 

EN/DEM = GND

--

20

--

Ω

Resistance

 

 

 

 

 

 

 

 

 

Current Sensing

 

 

 

 

 

 

 

Current Limit Source Current

 

LGATE = High

18

20

22

μA

 

 

 

 

 

 

 

 

Current Limiter Temperature

TCICS

On the basis of 25°C

--

4700

--

ppm/°C

Coefficient

 

 

 

 

 

 

 

 

Current Comparator Offset

 

GND to OC

−10

--

10

mV

Voltage

 

 

 

 

 

 

 

 

 

Zero Crossing Threshold

 

PHASE to GND, VEN/DEM = 5V

−10

--

5

mV

Voltage

 

 

 

 

 

 

 

 

 

Fault Protection

 

 

 

 

 

 

 

Current Limit Sense Voltage

 

GND − PHASE, RILIM = 10kΩ

170

200

230

mV

Output Under Voltage Threshold

VUVP

 

60

70

80

%

 

 

 

 

 

 

 

 

Over Voltage Protection

VOVP

With respect to error comparator

110

115

120

%

Threshold

 

threshold

 

 

 

 

 

 

Over Voltage Fault Delay

 

FB forced above OV threshold

--

20

--

μs

 

 

 

 

 

 

 

 

Under Voltage Lockout

 

Falling edge, PWM disabled below

3.7

3.9

4.1

V

Threshold

 

 

this level

 

 

 

 

 

 

Under Voltage Lockout

 

 

--

150

--

mV

Hysteresis

 

 

 

 

 

 

 

 

 

 

Soft-Start Ramp Time

tSS

From EN high to internal VREF

--

1.5

--

ms

reaches 0.71V (0Æ95%)

 

 

 

 

 

 

 

Under Voltage Blank Time

 

From EN signal going high

--

4.5

--

ms

Thermal Shutdown

 

TSD_PWM

 

--

155

--

°C

Thermal Shutdown Hysteresis

TSD_PWM

 

--

10

--

°C

 

 

 

 

 

 

 

 

Driver On-Resistance

 

 

 

 

 

 

UGATE Driver Source

RUGATEsr

BOOT to PHASE forced to 5V

--

2

--

Ω

UGATE Driver Sink

 

RUGATEsk

BOOT to PHASE forced to 5V

--

1.5

--

Ω

LGATE Driver Source

RLGATEsr

LGATE, High State

--

1.5

--

Ω

LGATE Driver Sink

 

RLGATEsk

LGATE, Low State

--

0.7

--

Ω

Dead Time

 

 

LGATE Rising (VPHASE = 1.5V)

--

30

--

ns

 

 

UGATE Rising

--

30

--

 

 

 

 

Internal BOOT Charging Switch

 

VDDP to BOOT, 10mA

--

--

90

Ω

On Resistance

 

 

 

 

 

 

 

 

 

Logic I/O

 

 

 

 

 

 

 

EN/DEM Input

Logic-Low

VIL

EN/DEM Low

--

--

0.8

V

 

 

EN/DEM High

2.9

--

--

Threshold Voltage

Logic-High

VIH

EN/DEM Float

--

2

--

 

 

 

 

 

 

To be continued

 

 

www.richtek.com

DS8204L-04 April 2011

6

 

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