Richtek RT9907PQV Schematic [ru]

Preliminary

RT9907

3 Channel DC/DC Converters IC with

High-Efficiency Step-up and Step-down

General Description

The RT9907 is a three channel power-supply solution for

digital still cameras and other battery-powered devices. It

integrates an asynchronous step-up and two synchronous

step-down DC-DC converters. The RT9907 is targeted for

applications that use two AA cells or a single lithium-ion

battery.

The three DC-DC converters (CH1, CH2, CH3) accept input

voltage from 1.5V to 5.5V. Each DC-DC converter has

better transient response and excellent stability by

providing current-mode control and external compensation

network. With built-in Internal MOSFET and up to 1.4MHz

operating frequency, the RT9907 allows minimum BOM

cost and PCB area.

The step-down DC-DC converters (CH2, CH3) can regulate

output voltage as low as 0.8V. Three operational modes

are available: PWM, PSM, Low-Dropout modes. At PWM

mode, Internal synchronous rectifier with low R

dramatically reduces conduction loss and achieve 94%

efficiency. It enters Low-Dropout mode when normal PWM

cannot provide regulated output voltage by continuously

turning on the upper P-MOSFET. No external Schottky

diode is required in practical application.

Each DC-DC converter has independent enable input and

soft-start function allowing versatile power sequence

combination. Complete protection functions are

implemented such as short circuit, over-voltage protection.

DS(ON)

Features

zz

1.5V to 5.5V Battery Input Voltage Range

z

zz

zz

z Main step-up DC-DC Converter

zz

``

`1.5V to 5.5V Adjustable Output Voltage

``

``

`Up to 90% Efficiency

``

``

`2.6A, 0.3

``

zz

z T wo Step-Down DC-DC Converters

zz

``

`0.8V to 5.5V Adjustable Output Voltage

``

``

`94% Efficiency

``

``

`100% Duty Cycle

``

zz

z Up to 1.4MHz Switching Frequency

zz

μμ

zz

z 1

μA Supply Current in Shutdown Mode

zz

μμ

zz

z Programmable Soft Start Function

zz

zz

z Independent Enable Pin (CH1, CH2, CH3)

zz

zz

z External Compensation Network (CH1, CH2, CH3)

zz

zz

z Short Circuit Protection (CH1, CH2, CH3)

zz

zz

z Over Voltage Protection (CH2)

zz

zz

z 24-Lead VQFN Package

zz

zz

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

zz

Ω Ω

Ω Internal Power Switch

Ω Ω

Applications

z Digital Still Camera

z PDAs

z Portable Device

Pin Configurations

(TOP VIEW)

The RT9907 is available in small VQFN-24L 4x4 package.

COMP1 EN2

COMP2

FB2

18

EN1

17

ENM

16

VDD2

15

LX2

14

PGND2

13

LX1

11

VDD1

PGND1

FB3

GND

EN3

Ordering Information

RT9907

Package Type
QV : VQFN-24L 4x4 (V-Type)

Operating Temperature Range
P : Pb Free with Commercial Standard

Note :

RichTek Pb-free 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.

COMP3

VDD3

LX3

PGND3

SS

RT

24 2223

1

2

3

4

5

6

7

GND

VQFN-24L 4x4

21 20 19

GND

8 9 10 12

FB1

VDDM

`100% matte tin (Sn) plating.

DS9907-03 November 2005 www.richtek.com

1

RT9907

Typical Application Circuit

1-cell Li+ Battery 3.4V to 4.2V

V

BAT

1.5V/500mA

10μF x 4

4.7nF

10μF x 2

200k

220k

Chip Enable

1nF

4.7μH

100pF

20k

10k

30k

1nF

1nF

Preliminary

V

BAT

2

VDD3

3

LX3

24

FB3

17

ENM

18

21

22

10

19

1

5

EN1

EN2

EN3

COMP1

COMP2

COMP3

SS

64

RT

RT9907

PGND3

14

10μF

8

VDDM

PGND2

PGND1

11 7 23

10μF

LX1

VDD1

FB1

VDD2

LX2

FB2

GND

GND

13

12

9

16

15

20

4.7μH

0.1μF

4.7μH

100pF

SS0520

680k

130k

150k

470k

5V/500mA

10μF x 4

V

10μF x 2

3.3V/500mA

10μF x 4

BAT

Figure 1. Typical Application Circuit for 1-cell Li+ Battery

DS9907-03 November 2005www.richtek.com

2

2-AA Battery 1.8V to 3.2V

V

BAT

1.5V/300mA

10μF x 4

4.7nF

10μF x 2

200k

220k

Chip Enable

1nF

4.7μH

100pF

20k

10k

30k

1nF

1nF

Preliminary

2

VDD3

3

LX3

24

FB3

17

ENM

18

EN1

21

EN2

22

EN3

10

COMP1

19

COMP2

1

COMP3

5

SS

RT

64

3.3V

8

VDDM

RT9907

PGND3

PGND2

11 7 23

14

10μF

LX1

VDD1

FB1

VDD2

LX2

FB2

GND

PGND1

GND

13

12

9

16

15

20

SS0520

470k

150k

4.7μH

100pF

4.7μH

220k

10μF x 2

10μF x 4

10μF x 2

470k

RT9907

V

BAT

I/O 3.3V/500mA

3.3V

2.5V/300mA

10μF x 4

Figure 2. Typical Application Circuit for 2-AA Battery Supply

DS9907-03 November 2005 www.richtek.com

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RT9907

Function Block Diagram

Preliminary

VDDM ENM

SS

RT

Soft-Start

OSC

PWM

OSC

Thermal

Shutdown

CH1

Current-MODE

Asynchronous

Step-Up

PWM

Boost

CH2

Current-MODE

Synchronous

Step-Down

PWM

Buck2

CH3

Current-MODE

Synchronous

Step-Down

PWM

Buck3

EN

EN1
VDD1

LX1

PGND1

COMP1
FB1

EN2
VDD2

LX2

PGND2

COMP2
FB2

EN3
VDD3

LX3

PGND3

COMP3
FB3

GND

ENM EN1 EN2 EN3 CH1 CH2 CH3

0 X X X Off Off Off

1 0 0 0 Off Off Off

1 1 0 0 On Off Off

1 1 1 0 On On Off

1 1 1 1 On On On

DS9907-03 November 2005www.richtek.com

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Functional Pin Description

Pin Number Pin Name Pin Function

Preliminary

RT9907

1 COMP3

2 VDD3

3 LX3

4 PGND3

5 SS

6 RT

7, 23

8 VDDM

9 FB1

10 COMP1

11 PGND1

12 VDD1

13 LX1

14 PGND2

15 LX2

16 VDD2

17 ENM

18 EN1

19 COMP2

GND

CH3 Feedback Compensation Pin.

CH3 Power Input Pin.

CH3 Switch Node. Drains of the internal P-Channel and N-Channel MOSFET switches.
Connect an inductor to LX3 pins together as close as possible.

Power Ground for CH3.

Sets the Soft Start interval of the converter. Connect a capacitor from this pin to ground.

Frequency setting resistor connection pin. Frequency is 500KHz if RT pin not connected

Analog Ground

Device Input Power Pin.

CH1 Feedback Input Pin.

CH1 Feedback Compensation Pin.

Power Ground for CH1

CH1 Power Input Pin. Connect output of Boost to this pin.

CH1 Switch Vode. Connect an inductor to LX1 Pins together as close as possible.

Power Ground for CH2.

CH2 Switch Node. Drains of the internal P-Channel and N-Channel MOSFET switches.
Connect an inductor to LX2 pins together as close as possible.

CH2 Power Input Pin.

Whole Device Control Pin. Tie this pin higher than 1.3V to enable the device. Tie below

0.4V to turn off the device.
CH1 Enable Input. Tie this pin higher than 1.3V to enable CH1. Tie below 0.4V to turn off
the CH1.

CH2 Feedback Compensation Pin.

20 FB2

21 EN2

22 EN3

24 FB3

Exposed Pad GND

DS9907-03 November 2005 www.richtek.com

CH2 Feedback Input.

CH2 Enable Input. Tie this pin higher than 1.3V to enable CH2. Tie below 0.4V to turn off
the CH2.
CH3 Enable Input. Tie this pin higher than 1.3V to enable CH3. Tie below 0.4V to turn off
the CH3.

CH3 Feedback Input.

Exposed pad should be soldered to PCB board and connected to GND.

5

RT9907

Preliminary

Absolute Maximum Ratings (Note 1)

z Supply Input Voltage, V
z LX1 Pin Switch Voltage ------------------------------------------------------------------------------------------ −0.3V to 7V
z LX2 Pin Switch Voltage ------------------------------------------------------------------------------------------ −0.3V to (V
z LX3 Pin Switch Voltage ------------------------------------------------------------------------------------------ −0.3V to (V

z Other I/O Pin Voltage ---------------------------------------------------------------------------------------------

z Power Dissipation, P

, V

DDM

DD1

@ TA = 25°C

D

, V

DD2,VDD3

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

−0.3 to 7V

−0.3V to (V

DD2

DD3

DDM

+ 0.3V)

+ 0.3V)

+ 0.3V)

VQFN-24L 4x4 ----------------------------------------------------------------------------------------------------- 1.85W

z Package Thermal Resistance (Note 3)

VQFN-24L 4x4, θJA------------------------------------------------------------------------------------------------ 54°C/W

z Junction Temperature Range------------------------------------------------------------------------------------ 0°C to 125°C

z Lead Temperature (Soldering, 10 sec.)----------------------------------------------------------------------- 260°C
z Operation Temperature Range ---------------------------------------------------------------------------------- −40°C to 85°C
z Storage Temperature Range ------------------------------------------------------------------------------------ −65°C to 150°C

z ESD Susceptibility (Note 2)

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

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

Electrical Characteristics

(V

=3.3V, TA = 25°C, Unless Otherwise specification)

DDM

Parameter Symbol Test Condition Min Typ Max Units

Supply Voltage

Minimum Startup Voltage (Boost) VST Boost loading < 1mA -- 1.5 -- V

VDDM Operating Voltage V

VDD1, VDD2, VDD3 Operating

Volta ge

V

V

V

VDDM Over Voltage Protection -- 6.5 -- V

Supply Current

Shutdown Supply Current I

CH1 DC/DC Converter I

CH2 DC/DC Converter Supply

Current

CH3 DC/DC Converter Supply

Current

I

I

VDDM Pin Voltage 2.4 -- 5.5 V

VDDM

VDD1

VDD2

VDD3

OFF

VDDM

VDDM

VDDM

VDD1, VDD2, VDD3 Pin

,

Voltage 1.5 5.5 V

V

pin=0V -- 0.01 1 μA

ENM

= 3.3V,

V

VDDM

V

= 0.9V

FB1

V

ENM

V

EN2

V

VDDM

V

FB2

V

ENM

V

EN2

V

VDDM

V

FB3

V

ENM

V

EN2

= 3.3V, V

= 0V, V

= 3.3V,

= 0.9V

= 3.3V, V

= 3.3V, V

= 3.3V,

= 0.9V

= 3.3V, V

= 0V, V

EN1

EN3

EN1

EN3

EN1

EN3

= 3.3V,

= 0V

= 0V,

= 0V

= 0V,

= 3.3V

-- 250 350 μA

-- 250 350 μA

-- 250 350 μA

To be continued

DS9907-03 November 2005www.richtek.com

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