Datasheet RN5T649 Datasheet (RICOH)

Charge pump for White LED

RN5T649

Development Specifications

Rev. 1.2

2009/05/19

RICOH COMPANY, LTD.

Electronic Devices Company

This specification is subject to change without notice.

RN5T649 CHARGE PUMP FOR WHITE LED

Table of Contents

1.

Outline........................................................................................................................................................................3

2. Feature .......................................................................................................................................................................3

3. Ordering Information ...............................................................................................................................................3

4. Pin Configuration......................................................................................................................................................4

5. Typical Application Circuit ......................................................................................................................................5

6. Pin Description ..........................................................................................................................................................6

7. Functional Blocks......................................................................................................................................................7

7.1 Single Wire Serial Pulse I/F of LDO1/2 .............................................................................................................7

7.2 LDO1/2 Electrical Characteristics ......................................................................................................................8

7.3 Charge Pump.......................................................................................................................................................9

7.3.1 Block Diagram ..........................................................................................................................................9

7.3.2 Backlight LED......................................................................................................................................... 10

7.3.3 Protection Circuit .................................................................................................................................... 11

7.3.4 Unused DIN_ pin ....................................................................................................................................11

7.3.5 Soft-start.................................................................................................................................................. 11

7.3.6 Luminance Control.................................................................................................................................. 12

7.3.7 Single Wire Serial Pulse I/F of LED Driver............................................................................................ 13

7.3.8 Charge Pump Electrical Characteristics .................................................................................................. 14

7.4 UVLO (Under Voltage Lock Out)....................................................................................................................15

7.5 Thermal Shutdown Circuit................................................................................................................................16

7.5.1 Thermal Shutdown Electrical Characteristics .........................................................................................16

8. Electrical Characteristics........................................................................................................................................17

8.1 Absolute Maximum Ratings .............................................................................................................................17

8.2 Recommendation of Operation Conditions.......................................................................................................17

8.3 DC Characteristics ............................................................................................................................................17

9. Package Information...............................................................................................................................................18

CHARGE PUMP FOR WHITE LED RN5T649

1. Outline

RN5T649 contains a constant frequency charge pump, which is optimized for White LED application. Output

enable/disable, LEDs current and LDOs ON/OFF are individually controllable through single wire serial pulse I/F.

2. Feature

z White LED Charge Pump

9 Current capability: Up to 92mA 9 1x/1.33x/1.5x switchable charge pump mode 9 Power up four LEDs for backlight: Up to 23mA/LED 9 Luminance control with 32steps from 0.25mA to 23mA 9 Soft-start

z Power Supply Function

9 LDO (150mA) × 2 (ON/OFF control through single wire serial pulse I/F) 9 LDO output voltage is settable in 0.05V step in range of 1.2V to 3.3V 9 Over current protection (All Regulators) and thermal shutdown

z Others

9 UVLO 9 Short-circuit Protection

z Package

9 20pin QFN package (Body size: 3.0 x 3.0 x 0.75mm, Pin pitch 0.4mm)

z Process

9 CMOS process

3. Ordering Information

RN5T649

LDO Output voltage : LDOUT1 / LDOUT2

U: 1.80V / 2.80V

V: 1.50V / 2.80V

CHARGE PUMP FOR WHITE LED RN5T649

4. Pin Configuration

LDOCTL

20

DIN1

19

DIN2

18

NC

GNDCOM

17

16

LEDCTL

C2M

C3P

VOUT

C1P

1

2

3

TOP VIEW

4

5

6

7

C2P

C1M

9

8

C3M

VCCCP

Fig 4-1 Pin Configuration

10

GNDCP

15

14

13

12

11

DIN3

DIN4

LDOUT2

VCCCOM

LDOUT1

CHARGE PUMP FOR WHITE LED RN5T649

5. Typical Application Circuit

VCCCP

4.7uF

GND

Controlled with GPIO of CPU

4.7uF

GND

Controlled with GPIO of CPU

Li-ion

Battery

GND

LDOCTL

VCCCOM

1uF

LDOUT2

1uF

LEDCTL

NR: Noise reduction

1uF 1uF 1uF

Charge Pump

@92mA (1x,1.33x,1.5x)

Thermal

Shutdown

NR

Logic

LDO1LDOUT1

LDO2

NR

RN5T649

Feed Back

Adjust Voltage

Current Driver

5bit DAC

VOUT

2.2µF

GNDCP

DIN1

@23mA

DIN2

@23mA

DIN3

@23mA

DIN4

@23mA

GNDCOM

GND

Fig 5-1 Typical Application Circuit

RN5T649 CHARGE PUMP FOR WHITE LED

6. Pin Description

No. Name I/O Description Notes

LEDCTL

1

2

3

4

5

6

7

8 VCCCP PWR Power supply for charge pump

9

10

11

12

13

14

15

16

17

18

19

20

C2M

C3P

VOUT

C1P

C2P

C1M

C3M

GNDCP

LDOUT1

VCCCOM

LDOUT2

DIN4

DIN3

NC

GNDCOM

DIN2

DIN1

LDOCTL

I ON/OFF control and Current setting of LED driver

- Charge pump boost capacitor connection

O

GND Ground for charge pump

O Output of LDO1.

PWR Power supply for LDO, UVLO, Logic block and TSHUT.

O Output of LDO2

O LED driver current control output

GND Ground for LDO, UVLO, Logic block and TSHUT.

O LED driver current control output

LED driver voltage output.

VOUT is high impedance during shutdown.

- Charge pump boost capacitor connection

- No connection *1

I LDO1/2 ON/OFF control input

Note*1: NC pin should be connected to GND or open.

Table 6-1 Pin Description

CHARGE PUMP FOR WHITE LED RN5T649

7. Functional Blocks

7.1 Single Wire Serial Pulse I/F of LDO1/2

RN5T649 has 2 Low Drop Output regulators, LDO1 and LDO2. At time of shipment, the output voltage can be set in

0.05 V steps by trimming.

ON/OFF operation of LDO1 and LDO2 is controllable with LDOCTL pin through single wire serial pulse I/F.

Please refer to the following timing chart. LDO1 and LDO2 are turned on after t

OUT (=20us typ) when LDOCTL

changes from “L” to “H”.

LDOCTL

LDO1

LDO2

t

tHI>10us

OUT

tOUT≒20us　(typ) tOFF≒70us (typ)

tLO>10us

tOFF

Fig 7-1 LDO ON/OFF Control 1

For the type of the bypass capacitor, it must be a ceramic type, not tantalum type, since the optimization design is based

on the ceramic type for the phase compensation.

*Timer description

・tOUT : If LDOCTL remains “H” more than 10us, the voltage appears to both LDOUT1 pin and LDOUT2 pin.

・tOFF : “L” pulse of LDOCTL pin more than 10us turns off both LDO1 and 2.

RN5T649 CHARGE PUMP FOR WHITE LED

7.2 LDO1/2 Electrical Characteristics

Unless otherwise specified, VCCCOM=3.6V, Ta=25℃, Cout=1.0uF

Symbol Parameter Condition Min Typ Max Units

LDOUT*1

VACC

Range

Output Voltage

Accuracy

50uA＜IOUT＜150mA,

VOUT+0.5V≦V

& 3.0V≦V

IOUT Output Current - 150 mA

ISHT Short Current VOUT=0V 130 mA

Output Voltage

VDRP Drop-out Voltage

ΔVOUT

Line Regulation

IOUT=150mA,T

VOUT+0.5V≦VCCCOM≦4.5V

ΔVCCCOM

ΔVOUT

Load Regulation

50uA＜IOUT＜150mA

ΔIOUT

ΔVOUT

ΔT

a

RR Ripple Rejection

EN

BC *2 Bypass Capacitor

Icc

Output Voltage

Temperature

Coefficient

Output Noise

(RMS)

Consumption

-40℃≦T

f=10Hz-10kHz, C

BW=100Hz-100kHz, C

0uA＜IOUT＜150mA

Normal (IOUT=0mA) 70

Current

- 1.2 3.3 V

(VCCCOM)

BATT

(VCCCOM)≦4.5V

BATT

=85℃,VOUT≧2.8V

a

-2% +2% V

300 mV

2.4 mV

IOUT=150mA

25 mV

≦85℃

a

out

=1.0uF

+

60 dB

100

IOUT=75mA

=1.0uF

out

IOUT=75mA

50 uVrms

1.0 uF

OFF 1

ppm/℃

uA

Table 7-1 LDO1/2 Electrical Characteristics

Note*1: The output voltage will be fixed (in 0.05V step) by trimming at shipment.

Note*2: For optimized phase compensation, the bypass capacitor must be a ceramic type.

CHARGE PUMP FOR WHITE LED RN5T649

7.3 Charge Pump

RN5T649 drives up to 4 white LEDs with regulated constant current. Utilizing 1x/1.33x/1.5x charge pump modes

achieves high-efficiency. On/off of LED is individually controllable through single wire serial pulse I/F. Also, the

luminance of LED is individually controllable through single wire serial pulse I/F.

The capacitor is highly recommended to be ceramic.

7.3.1 Block Diagram

VCCCP

LEDCTL

NR: Noise reduction

1uF

C1M

C1P

C2M

1uF

Charge Pump

@92mA( 1x,1.33x,1.5x)

Thermal

Shutdown

NR

1uF

C2P

C3M

Feed Back

Adjust Voltage

Current Driver

5bit DAC

C3P

VOUT

2.2µF

GNDCP

DIN1

@23mA

DIN2

@23mA

DIN3

@23mA

DIN4

@23mA

GNDCOM

GND

Fig 7-2 Charge Pump Circuit Diagram

CHARGE PUMP FOR WHITE LED RN5T649

7.3.2 Backlight LED

For maximized power efficiency, Charge pump operates 1x mode, 1.33x mode and 1.5x mode, where the operation

mode is determined by comparing the forward voltage of each LED with the input voltage.

Initial and 1x mode

When any LED channel is enabled and VCCCP voltage is greater than Charge pump output (VOUT), Charge pump

initially starts in 1x mode and VOUT is pulled up to VCCCP. During start-up, built-in Soft-start circuitry will prevent

excessive inrush current. Charge pump circuit will stay in 1x mode if:

VOUT - Vf > 230mV (1)

VOUT: Charge pump output

Vf: White LED forward voltage

230mV: Mode transition threshold voltage when LED output current is set at 23mA.

1x or 1.33x transition

When VCCCP falls and DIN_ pin voltage drops below the mode transition threshold voltage 230mV for 100us, Charge

pump circuit switches to 1.33x mode to boost voltage. Charge pump circuit will stay in 1.33x mode if:

VOUT - Vf > 230mV (2)

Every 1sec, Charge pump circuit resets to 1x mode and stays in 1x mode for approximately 100us to judge whether it

changes to 1.33x mode or stays in 1x mode.

1.33x or 1.5x transition

When VCCCP falls and DIN_ pin voltage drops further below the mode transition threshold voltage 230mV for 100us,

Charge pump circuit switches to 1.5x mode to boost voltage.

Every 1sec, Charge pump circuit resets to 1.33x mode and stays in 1.33x mode for approximately 100us to judge

whether it changes to 1.5x mode or stays in 1.33x mode.

Mode transition

Reset to 1x mode

Reset to 1.33x

mode every sec

every sec

Initial

LED channel enabled

VOUT soft start

VOUT pulled up to VCCCP

1x Mode, LED On

Min. DIN_ lower than 230mV.

1.33x Mode

Min. DIN_ lower than 230mV.

1.5x Mode

VOUT = GND

VOUT = VCCCP-Ro*Iled

DIN_=VOUT-Vf

VOUT = 1.33*VCCCP-Ro*Iled

DIN_=VOUT-Vf

VOUT = 1.5*VCCCP-Ro*Iled

DIN_=VOUT-Vf

Ro:Output Resistanse Iled:DIN1-4 LED current

Fig 7-3 Mode Transition Diagram

CHARGE PUMP FOR WHITE LED RN5T649

7.3.3 Protection Circuit

When any DIN_ pin is floating or grounded, VOUT voltage is limited below protection voltage by gating on/off charge

pump. In case any LED fails as an open circuit, VOUT voltage is also limited. Besides, when VOUT is smaller than

approximately 1.2V, Charge pump will stop.

7.3.4 Unused DIN_ pin

Please ground unused DIN_ pin to avoid over-voltage protection status.

VCCCP

LEDCTL

1uF

C1M

Shutdown

NR

NR: Noise reduction

C1P

Charge Pump

@92mA (1x,1.33x,1.5x)

Thermal

1uF

C2M

1uF

C2P

C3M

Feed Back

Adjust Voltage

Current Driver

5bit DAC

C3P

VOUT

2.2µF

GNDCP

DIN1

@23mA

DIN2

@23mA

DIN3

DIN4

GNDCOM

GND

Fig 7-4 Ground Unused DIN_pin

7.3.5 Soft-start

RN5T649 includes Soft-start circuitry to prevent excessive inrush current during turn on. (The internal resistance

gradually increases, just after LEDs enabled.)

When charge pump turns on, the capacitors are charged directly from input voltage. Soft-start is achieved by the amount

of capacitor available to capacitor for approximately 100us.

CHARGE PUMP FOR WHITE LED RN5T649

7.3.6 Luminance Control

RN5T649 charge pump drives 4 LEDs with regulated constant current for uniformed intensity. LEDCTL input

enables/disables LED and adjusts current for each LED with 32 steps from 0.25mA to 23mA.

14.5

tHI > 2.8us

13

12.5

18 19 20 21 22 23 24 25 26 27 28 29 3 0 31 32

11

10

9

8.5 8

7

6.5 6

5.5 5

4.5 4

3.5 3

2.5 2

1.5 1

23

0.5

0.25

LEDCTL

MLED

I

INITIAL tHI > 300µs

Soft-start

23

tLO 2.8us to 250µs

1 2 345678 91011121314151617

22

20

19.5 19

18

17

16

15

Fig 7-5 Luminance Control Diagram

・tHI : Pulling LEDCTL pin “H” for 300us or more enables LED. The minimum “H” time of LEDCTL pin is 2.8us.

・tOFF : “L” pulse of LEDCTL pin longer than 1ms turns off LED.

Luminance Count value

OFF⇒ON(23mA)

22mA 1 (01h) 20mA 2 (02h)

19.5mA 3 (03h) 19mA 4 (04h) 18mA 5 (05h) 17mA 6 (06h) 16mA 7 (07h) 15mA 8 (08h)

14.5mA 9 (09h) 13mA 10 (0Ah)

12.5mA 11 (0Bh) 11mA 12 (0Ch) 10mA 13 (0Dh) 9mA 14 (0Eh)

8.5mA 15 (0Fh) 8mA 16 (10h) 7mA 17 (11h)

6.5mA 18 (12h) 6mA 19 (13h)

5.5mA 20 (14h) 5mA 21 (15h)

4.5mA 22 (16h) 4mA 23 (17h)

3.5mA 24 (18h) 3mA 25 (19h)

2.5mA 26 (1Ah) 2mA 27 (1Bh)

1.5mA 28 (1Ch) 1mA 29 (1Dh)

0.5mA 30 (1Eh)

0.25mA 31 (1Fh) 23mA 32 (20h) … …

0 (00h)

Table 7-2 LED Luminance Control

CHARGE PUMP FOR WHITE LED RN5T649

7.3.7 Single Wire Serial Pulse I/F of LED Driver

When LEDCTL goes high, LEDs are enabled at full luminance. After, the subsequent low going pulse reduces LED

current in linear (1.0mA or 0.5mA) scale.

7.3.7.1 Disable LED

LED can be powered off by driving LEDCTL pin low longer than tOFF.

tOFF

2ms (typ)

LEDCTL

Soft-start

1 2 34 12

23

22

20

19.5

Soft-start

23

22

20

I

LED

Fig 7-6 Disable LED

7.3.7.2 Initialization of LED

Luminance can be adjusted to initial value by driving LEDCTL pin “H” longer than tRESET

remains power-on.)

LEDCTL

I

LED

Soft-start

tRESET

2ms (typ) 2ms (typ)

23

22

20

19.5 19

1 51 2 34 23

22

20

19.5

LEDCTL

I

LED

Soft-start

1 2 34 67

23

22

tRESET

20

19.5 19

but not over tOFF. (LED

18

17

16

Fig 7-7 Initialization of LED

* Timer description

・tRESET timer starts at falling edge of the input clock from LEDCTL and is cleared at rising edge of input clock from

LEDCTL.

・tOFF timer starts at rising/falling edge of the input clock from LEDCTL and turns off when timer overflows.

RN5T649 CHARGE PUMP FOR WHITE LED

7.3.8 Charge Pump Electrical Characteristics

Unless otherwise specified, VCCCP=3.6V, VCCCOM=3.6V, Ta=25℃, C1=C2=C3=1uF, Cout=2.2uF

Symbol Parameter Condition Min Typ Max Units

Charge Pump

VIN Operating Voltage VCCCP voltage 3.0 4.5 V

I

Max. Output current

OUT

RON Output resistance

1.33x ： (1.33xVCCCP-Vout)/Iout

1.5x ： (1.5xVCCCP-Vout)/Iout

F

Switching Frequency - 1.0 MHz

OSC

T

Soft-start time - 100 us

SOFT

Icc Consumption Current

VCCCP≧3.0V

1x ： (VCCCP-Vout)/Iout

1x mode

1.33X mode

1.5x mode

92 mA

0.8

3.2

Ω

5.8

1

5

mA

5

Iss Standby consumption current VCCCP current 5 uA

I

Current limit VOUT shorted 120 mA

LIM

1x to 1.33x transition

V

TH1

threshold

1.33x to 1.5x transition

- 230 mV

threshold

V

TIM

1x to 1.3x transition time

1.33x to 1.5x transition time

- 100 us

LED Driver

Isink Maximum Sink Current Each DIN1-4 23 mA

ACC LED current accuracy Setting DATA Max , DIN*=0.23V -5 5 %

I

*1 LED current matching Setting DATA Max ,Vfdiff<0.4V -2 2 %

MAT

V

Current Regulator Dropout Setting DATA Max 230 mV

Drop

I

DIN1-4 leakage in shutdown - 0.01 uA

LEAK

Table 7-3 Charge Pump Electrical Characteristics

Note*1: The matching is given by (Iave - Iled ) / Iave. The Iave means the average current of 4 LEDs.

The matching is defined without Vf voltage difference between channels.

Iave = (Iled1 + Iled2 + Iled3 + Iled4 ) / 4

RN5T649 CHARGE PUMP FOR WHITE LED

7.4 UVLO (Under Voltage Lock Out)

Unless otherwise specified, Ta=25℃

Symbol Parameter Condition Min Typ Max Units

V

Under voltage lock out threshold VCCVIN rising 2.25 V

Release

V

Under voltage lock out threshold VCCVIN falling 2.05 2.20 2.35 V

Detect

V

UVLO Hysteresis - 50 mV

HYS

Table 7-4 UVLO Electrical Characteristics

RN5T649 CHARGE PUMP FOR WHITE LED

7.5 Thermal Shutdown Circuit

Overheat state can be detected by comparing the output voltages from two temperature detection circuits, which have

different temperature characteristics. If the overheat state is detected, RN5T649 will turn off to protect itself from

overheating.

7.5.1 Thermal Shutdown Electrical Characteristics

Unless otherwise specified, VCCCOM=3.6V, Ta=25℃

Symbol Parameter Condition Min Typ Max Units

T

Detected Temperature - 140

DET

T

Return Temperature - 110

RET

Icc Consumption Current - 10 uA

Table 7-5 Thermal Shutdown Electrical Characteristics

℃

RN5T649 CHARGE PUMP FOR WHITE LED

8. Electrical Characteristics

8.1 Absolute Maximum Ratings

Symbol Parameter Condition Rated value Units

VCC_abs Power Supply Voltage Battery Voltage Input Pins

Vin Input Voltage Range All Input Pins

PD

Package

Allowable Dissipation

T

Storage Temperature -

stg

Mounted on Board,

=70℃

T

a

Table 8-1 Absolute Maximum Ratings

8.2 Recommendation of Operation Conditions

Symbol Parameter Condition Min Typ Max Units

VCC_Op Power Supply Voltage

VCC_Rec Power Supply Voltage

Ta Temp. of Operation - -40 85

Battery Voltage Input Pins

(Operation Conditions)

Battery Voltage Input Pins

(Recommendation of

Operation Conditions)

2.7 3.6 4.5 V

3.0 3.6 4.5 V

-0.3～6.0

-0.3～VCC*+0.3

950 mW

-55～+125 ℃

V

℃

Table 8-2 Recommendation of Operation Conditions

8.3 DC Characteristics

Unless otherwise specified, VCCCOM=3.6V, Ta=25℃

Symbol Parameter Condition Min Typ Max Units

Vih “H” Input Voltage - 1.6 V

Vil “L” Input Voltage - 0.4 V

I

Input Leakage Current 1 VCCCOM -3 3 uA

IL1

Ishut

Shutdown Consumption

Current

LDOCTL=LEDCTL=“L” 1 uA

Table 8-3 DC Characteristics

CHARGE PUMP FOR WHITE LED RN5T649