B. High Efficiency, Main Power Supply Controllers for Notebook Computers. Features. General Description. Applications. Marking Information

RT8206A/B High Efficiency, Main Power Supply Controllers for Notebook Computers General Description Features The RT8206A/B dual step-down, Switch Mo...
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RT8206A/B High Efficiency, Main Power Supply Controllers for Notebook Computers General Description

Features

The RT8206A/B dual step-down, Switch Mode Power Supply (SMPS) controller generates logic supply voltages in battery powered systems. The RT8206A/B includes two Pulse Width Modulation (PWM) controllers fixed at 5V/3.3V or adjustable from 2V to 5.5V. An optional external charge pump can be monitored through SECFB (RT8206A). This device also features a linear regulator providing a fixed 5V output. The linear regulator provides up to 70mA output current with automatic linear regulator bootstrapping to the BYP input. The RT8206A/B includes on-board power up sequencing, the power good outputs, internal soft-start, and internal soft-discharge output that prevents negative voltages on shutdown.

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A constant on-time PWM control scheme operates without sense resistors and provides 100ns response to load transients while maintaining a relatively constant switching frequency. The unique ultrasonic mode maintains the switching frequency above 25kHz, which eliminates noise in audio applications. Other features include Diode Emulation Mode (DEM), which maximizes efficiency in light load applications, and fixed frequency PWM mode, which reduces RF interference in sensitive application. The RT8206A/B is available in the WQFN-32L 5x5 package.

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Wide Input Voltage Range 6V to 25V Dual Fixed 5V/3.3V Outputs or Adjustable from 2V to 5.5V, 1.5% Accuracy Secondary Feedback Input Maintains Charge Pump Voltage (RT8206A) Independent Enable and Power Good 5V Fixed LDO Output : 70mA 2V Reference Voltage ±1% : 50μ μA Constant ON-Time Control with 100ns Load Step Response Frequency Selectable via TON Setting RDS(ON) Current Sensing and Programmable Current Limit Selectable PWM, DEM or Ultrasonic Mode Internal Soft-Start with 5 Steps Current Limiting and Soft-Discharge High Efficiency Up to 97% 5mW Quiescent Power Dissipation Thermal Shutdown RoHS Compliant and Halogen Free

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Notebook and Sub-Notebook Computers 3-Cell and 4-Cell Li+ Battery-Powered Devices

Ordering Information

Marking Information

RT8206

RT8206AGQW RT8206AGQW : Product Number

Package Type QW : WQFN-32L 5x5 (W-Type) Lead Plating System G : Green (Halogen Free and Pb Free) A : With SECFB B : Without SECFB Note : Richtek products are : `

RoHS compliant and compatible with the current require-

`

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

ments of IPC/JEDEC J-STD-020.

DS8206A/B-06 August 2011

RT8206A GQW YMDNN

YMDNN : Date Code

RT8206BGQW RT8206BGQW : Product Number

RT8206B GQW YMDNN

YMDNN : Date Code

www.richtek.com 1

RT8206A/B Pin Configurations

25 24

2

23

3

22

ENLDO NC VIN LDO NC

4

21

GND

5

BOOT2 LGATE2 PGND GND SECFB PVCC LGATE1 BOOT1

20

6

19

7

18

33

17

32

31

30

29

28

27

26

25

REF TON VCC

1

24

2

23

3

22

ENLDO NC VIN LDO NC

4

21

GND

5

20

6

19

7

18

33

17

9

10

11

12

13

14

15

16

9

10

11

12

13

14

15

16

BYP

FB1

ILIM1

PGOOD1

EN1

UGATE1

PHASE1

BYP

VOUT1

FB1

ILIM1

PGOOD1

EN1

UGATE1

PHASE1

8

VOUT1

8

PHASE2

PHASE2

26

UGATE2

UGATE2

27

EN2

EN2

28

PGOOD2

PGOOD2

29

SKIP

SKIP

30

VOUT2

VOUT2

31

1

ILIM2

ILIM2

32

REF TON VCC

FB2

FB2

(TOP VIEW)

WQFN-32L 5x5

WQFN-32L 5x5

RT8206A

RT8206B

BOOT2 LGATE2 PGND GND NC PVCC LGATE1 BOOT1

Typical Application Circuit VIN 6V to 25V

R14 3.9

C1 10µF

RT8206A/B 6 VIN

C18 0.1µF

Q1

C3 220µF

PHASE2 25

R3 0

17

LGATE2 23

18 LGATE1 9

C8

C9 1µF

C7 0.1µF

3 VCC

0.1µF

C19

C11 0.1µF

R7 0 C16 1µF

11 FB1 32 FB2

ILIM2

19 PVCC

SKIP

7 LDO

C15 0.22µF

R6 100k

28

R13 100k

C17 220µF

R10

PVCC PVCC

5V Enable

ON

3.3V Enable

OFF

LDO Control

31

TON 2

GND

VOUT2 3.3V

C14

13

EN1 14 EN2 27

20 SECFB/NC R12 39k

L2 4.7µH

Q4

ILIM1 12

R11 200k

CP

PGOOD1

C12 10µF

C13 10µF

Q2

R8 0

VOUT2 30 REF 1

ENLDO 4

D4

R9 0

PGND 22

PGOOD2

D2 D3

BYP

10 VOUT1

C5 0.1µF

D1

BOOT1

16 PHASE1

C4

C6 0.1µF

24

15 UGATE1

Q3

R5

BOOT2

R4 0

C2 0.1µF

L1 6.8µH

VOUT1 5V

UGATE2 26

29

VIN R1 180k R2 180k

Frequency Control PWM/DEM/Ultrasonic

21, 33 (Exposed Pad)

C10 4.7µF

Figure 1. Fixed Voltage Regulator

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DS8206A/B-06 August 2011

RT8206A/B VIN 6V to 25V

R14 3.9

C1 10µF

RT8206A/B 6 VIN

C18 0.1µF R4 0

Q1

R3 0 C2 0.1µF

L1 6.8µH

VOUT1 5V C3 220µF

BOOT2 15 UGATE1 17

18 LGATE1 9

C4 D1 C6 0.1µF

BYP

C9 1µF

C7 0.1µF

C8 0.1µF

C23 C20 0.1µF

R15 15k

CP

C19

20 SECFB/NC R12 39k

11 FB1 R7 0

R16 10k

C16 1µF C10 4.7µF

19 PVCC 7 LDO

L2 4.7µH

Q4

C17 220µF

R10

R17 11.5k

C15 0.22µF

SKIP GND

C22 C21 0.1µF

PVCC PVCC

ON

3.3V Enable

OFF

LDO Control

VIN R1 180k R2 180k

31

29

R18 10k

5V Enable

ILIM1 12

TON 2

R6 100k R13 100k

PGOOD2 28

ILIM2

VOUT2 3.3V

C14

13

ENLDO 4

R11 200k

C11 0.1µF

VOUT2 30 FB2 32 REF 1

C12 10µF

R8 0

PGND 22

EN1 14 EN2 27

D4

C13 10µF

Q2

LGATE2 23

PGOOD1 3 VCC

24

R9 0

PHASE2 25

10 VOUT1

C5 0.1µF

D2 D3

BOOT1

16 PHASE1

Q3

R5

UGATE2 26

Frequency Control PWM/DEM/Ultrasonic

21, 33 (Exposed Pad)

Figure 2. Adjustable Voltage Regulator

DS8206A/B-06 August 2011

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RT8206A/B Function Block Diagram TON SKIP

BOOT1

BOOT2

UGATE1

UGATE2

PHASE1

PVCC

PHASE2

PVCC SMPS1 PWM Buck Controller

LGATE1 PGND

SMPS2 PWM Buck Controller

LGATE2 VOUT2 FB2 ILIM2 PGOOD2

VOUT1 FB1 ILIM1 PGOOD1

GND

SW Threshold VCC PVCC ENLDO EN1 EN2

BYP Internal Logic

LDO

Power On Sequence Clear Fault Latch

Thermal Shutdown

LDO

REF

REF

VIN

Function Block Diagram TON

VIN

UGATE On-Time Compute

VOUT

TON

Q 1-Shot

R

TOFF TRIG 1-Shot Q

TRIG REF

-

- Comp

+

+

+ -

LGATE

FB 1.1 x VREF

Over Voltage + Fault Latch -

VCC

-

0.7 x VREF

Blanking Time + Under Voltage

+

Current Limit

-

0.9 x VREF

PGOOD

+

ILIM

-

SS Time

+

25kHz Detector Zero Detector

+

-

PHASE

-

SKIP

PWM Controller (One Side) www.richtek.com 4

DS8206A/B-06 August 2011

RT8206A/B Functional Pin Description REF (Pin 1)

VOUT1 (Pin 10)

2V Reference Output. Bypass to GND with a 0.22μF capacitor. REF can source up to 50μA for external loads. Loading REF degrades FBx and output accuracy according to the REF load regulation error.

SMPS1 Output Voltage Sense Input. Connect this pin to the SMPS1 output. VOUT1 is an input to the Constant on-time-PWM one-shot circuit. It also serves as the SMPS1 feedback input in fixed voltage mode.

TON (Pin 2)

FB1 (Pin 11)

Frequency Select Input. (VOUT1/VOUT2 switching frequency, respectively) :

SMPS1 Feedback Input. Connect FB1 to VCC or GND for fixed 5V operation. Connect FB1 to a resistive voltage divider from VOUT1 to GND to adjust output from 2V to 5.5V.

TON = VCC, (200kHz / 250kHz) TON = REF, (300kHz / 375kHz) TON = GND, (400kHz / 500kHz) VCC (Pin 3) Analog Supply Voltage Input for the PWM Core. Bypass to GND with a 1μF ceramic capacitor ENLDO (Pin 4) LDO Enable Input. The REF/LDO is enabled if ENLDO is within logic high level and disable if ENLDO is less than the logic low level. NC (Pin 5, 8) No Internal Connection. VIN (Pin 6) Power supply Input. VIN is used for the constant on-time PWM one shot circuits. VIN is also used to power the linear regulators. The linear regulators are powered by SMPS1 if VOUT1 is set greater than 4.66V and BYP is tied to VOUT1. Connect VIN to the battery input and bypass with a 1μF capacitor. LDO (Pin 7) Linear Regulator Output. LDO can provide a total of 70mA external loads. The LDO regulates a fixed 5V output. When the BYP is within 5V switchover threshold, the internal regulator shuts down and the LDO output pin connects to BYP through a 1.5Ω switch. Bypass LDO output with a minimum of 4.7μF ceramic. BYP (Pin 9) BYP is the switchover source voltage input for the LDO. DS8206A/B-06 August 2011

ILIM1 (Pin 12) SMPS1 Current Limit Adjustment. The GND − PHASE1 current limit threshold is 1/10th the voltage seen at ILIM1 over a 0.5V to 2V range. There is an internal 5μA current source from VCC to ILIM1. The logic current limit threshold is default to 100mV if ILIM1 is higher than (VCC − 1V). PGOOD1 (Pin 13) SMPS1 Power Good Open-Drain Output. PGOOD1 is low when the SMPS1 output voltage is more than 7.5% below the normal regulation point or during soft-start. PGOOD1 is high impedance when the output is in regulation and the soft-start circuit has terminated. PGOOD1 is low in shutdown. EN1 (Pin 14) SMPS1 Enable Input. The SMPS1 will be enabled if EN1 is greater than the logic high level and disabled if EN1 is less than the logic low level. If EN1 is connected to REF, the SMPS1 starts after the SMPS2 reaches regulation (delay start). Drive EN1 below 0.8V to clear fault level and reset the fault latches. UGATE1 (Pin 15) High Side MOSFET Floating Gate Driver Output for SMPS1. UGATE1 swings between PHASE1 and BOOT1. PHASE1 (Pin 16) Inductor Connection for SMPS1. PHASE1 is the internal lower supply rail for the UGATE1 high side gate driver. PHASE1 is the current sense input for the SMPS1. www.richtek.com 5

RT8206A/B BOOT1 (Pin 17)

PHASE2 (Pin 25)

Boost Flying Capacitor Connection for SMPS1. Connect to an external capacitor according to the typical application circuits.

Inductor Connection for SMPS2. PHASE2 is the internal lower supply rail for the UGATE2 high side gate driver. PHASE2 is the current sense input for the SMPS2.

LGATE1 (Pin 18)

UGATE2 (Pin 26)

SMPS1 Synchronous-Rectifier Gate drive Output. LGATE1 swings between PGND and PVCC.

High Side MOSFET Floating Gate Driver Output for SMPS2. UGATE2 swings between PHASE2 and BOOT2.

PVCC (Pin 19)

EN2 (Pin 27)

PVCC is the supply voltage for the low side MOSFET driver LGATEx. Connect a 5V power source to the PVCC pin (bypass with 1μF MLCC capacitor to PGND if necessary). There is an internal 10Ω connecting from PVCC to VCC. Make sure that both VCC and PVCC are bypassed with 1μF MLCC capacitors.

SMPS2 Enable Input. The SMPS2 will be enabled if EN2 is greater than the logic high level and be disabled if EN2 is less than the logic low level. If EN2 is connected to REF, the SMPS2 starts after the SMPS1 reaches regulation (delay start). Drive EN2 below 0.8V to clear fault level and reset the fault latches.

SECFB (Pin 20) (RT8206A)

PGOOD2 (Pin 28)

The SECFB is used to monitor the optional external 14V charge pump. Connect a resistive voltage divider from the 14V charge pump output to GND to detect the output. If SECFB drops below the threshold voltage, LGATE1 will be turned on for 300ns. This will refresh the external charge pump driven by LGATE1 without over discharging the output voltage.

SMPS2 Power Good Open-Drain Output. PGOOD2 is low when the SMPS2 output voltage is more than 7.5% below the normal regulation point or during soft-start. PGOOD2 is high impedance when the output is in regulation and the soft-start circuit has terminated. PGOOD2 is low in shutdown. SKIP (Pin 29)

NC (Pin 20) (RT8206B)

SMPS Operation Mode Control.

No Internal Connection.

SKIP = GND : DEM operation

GND [Pin 21, 33 (Exposed Pad)]

SKIP = REF : Ultrasonic Mode operation

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

SKIP = VCC : PWM operation. VOUT2 (Pin 30)

Power Ground for SMPS controller. Connect PGND externally to the underside of the exposed pad.

SMPS2 Output Voltage Sense Input. Connect this pin to the SMPS2 output. VOUT2 is an input to the constant on-time-PWM one-shot circuit. It also serves as the SMPS2 feedback input in fixed voltage mode.

LGATE2 (Pin 23)

ILIM2 (Pin 31)

SMPS2 Synchronous-Rectifier Gate drive Output. LGATE2 swings between PGND and PVCC.

SMPS2 Current Limit Adjustment. The GND − PHASE2 current limit threshold is 1/10th the voltage seen at ILIM2 over a 0.5V to 2V range. There is an internal 5μA current source from VCC to ILIM2. The logic current limit threshold is default to 100mV value if ILIM2 is higher than (VCC − 1V).

PGND (Pin 22)

BOOT2 (Pin 24) Boost Flying Capacitor Connection for SMPS2. Connect this pin to an external capacitor according to the typical application circuits. www.richtek.com 6

DS8206A/B-06 August 2011

RT8206A/B FB2 (Pin 32) SMPS2 Feedback Input. Connect FB2 to VCC or GND for fixed 3.3V operation. Connect FB2 to a resistive voltage divider from VOUT2 to GND to adjust output from 2V to 5.5V.

DS8206A/B-06 August 2011

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RT8206A/B Absolute Maximum Ratings z z

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(Note 1)

VIN, ENLDO to GND ---------------------------------------------------------------------------------------------- –0.3V to 30V PHASEx to GND DC --------------------------------------------------------------------------------------------------------------------- –0.3V to 30V

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