RN5T659

Charge pump for White LED
RN5T659
Development Specifications
Rev. 1.2
2009/05/19
RICOH COMPANY, LTD.
Electronic Devices Company
This specification is subject to change without notice.
RN5T659 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) ....................................................................................................................14
7.5
Thermal Shutdown Circuit................................................................................................................................15
7.5.1
8.
9.
Thermal Shutdown Electrical Characteristics ......................................................................................... 15
Electrical Characteristics........................................................................................................................................16
8.1
Absolute Maximum Ratings .............................................................................................................................16
8.2
Recommendation of Operation Conditions.......................................................................................................16
8.3
DC Characteristics ............................................................................................................................................16
Package Information...............................................................................................................................................17
©2009
Rev. 1.2
Page 2
RN5T659 CHARGE PUMP FOR WHITE LED
1. Outline
RN5T659 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 115mA
9 1x/1.33x/1.5x switchable charge pump mode
9 Power up five 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
RN5T659□
LDO Output voltage : LDOUT1 / LDOUT2
U : 1.80V / 2.80V
V : 1.50V / 2.80V
©2009
Rev. 1.2
Page 3
RN5T659 CHARGE PUMP FOR WHITE LED
4. Pin Configuration
Fig 4-1 Pin Configuration
©2009
Rev. 1.2
Page 4
RN5T659 CHARGE PUMP FOR WHITE LED
5. Typical Application Circuit
Fig 5-1 Typical Application Circuit
©2009
Rev. 1.2
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RN5T659 CHARGE PUMP FOR WHITE LED
6. Pin Description
No.
Name
I/O
1
LEDCTL
I
ON/OFF control and Current setting of LED driver
2
C2M
-
Charge pump boost capacitor connection
3
C3P
-
Charge pump boost capacitor connection
O
LED driver voltage output.
VOUT is high impedance during shutdown.
4
VOUT
Description
5
C1P
-
Charge pump boost capacitor connection
6
C2P
-
Charge pump boost capacitor connection
7
C1M
-
Charge pump boost capacitor connection
8
VCCCP
PWR
9
C3M
-
10
GNDCP
GND
11
LDOUT1
O
12
VCCCOM
PWR
13
LDOUT2
O
Output of LDO2
14
DIN5
O
LED driver current control output
15
DIN4
O
LED driver current control output
16
DIN3
O
LED driver current control output
17
GNDCOM
GND
18
DIN2
O
LED driver current control output
19
DIN1
O
LED driver current control output
20
LDOCTL
I
LDO1/2 ON/OFF control input
Notes
Power supply for charge pump
Charge pump boost capacitor connection
Ground for charge pump
Output of LDO1.
Power supply for LDO, UVLO, Logic block and TSHUT.
Ground for LDO, UVLO, Logic block and TSHUT.
Table 6-1 Pin Description
©2009
Rev. 1.2
Page 6
RN5T659 CHARGE PUMP FOR WHITE LED
7. Functional Blocks
7.1 Single Wire Serial Pulse I/F of LDO1/2
RN5T659 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 tOUT (=20us typ) when LDOCTL
changes from "L" to "H".
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.
©2009
Rev. 1.2
Page 7
RN5T659 CHARGE PUMP FOR WHITE LED
7.2 LDO1/2 Electrical Characteristics
Unless otherwise specified, VCCCOM=3.6V, Ta=25℃, Cout=1.0uF
Symbol
LDOUT*1
Parameter
Output Voltage
Range
VACC
Output Voltage
Accuracy
50uA＜IOUT＜150mA,
VOUT+0.5V≦VBATT(VCCCOM)
& 3.0V≦VBATT(VCCCOM)≦4.5V
IOUT
Output Current
-
ISHT
Short Current
VOUT=0V
130
mA
Drop-out Voltage
IOUT=150mA,Ta =85℃,VOUT≧2.8V
300
mV
2.4
mV
50uA＜IOUT＜150mA
25
mV
-40℃≦Ta≦85℃
+100
ppm/℃
60
dB
50
uVrms
uF
VDRP
ΔVOUT
ΔVCCCOM
ΔVOUT
ΔIOUT
ΔVOUT
ΔTa
RR
EN
BC *2
Icc
Line Regulation
Load Regulation
Condition
Min
-
Max
Units
1.2
3.3
V
-2%
+2%
V
150
mA
VOUT+0.5V≦VCCCOM≦4.5V
IOUT=150mA
Typ
Output Voltage
Temperature
Coefficient
Ripple Rejection
f=10Hz-10kHz, Cout=1.0uF
IOUT=75mA
Output Noise
BW=100Hz-100kHz, Cout=1.0uF
(RMS)
IOUT=75mA
Bypass Capacitor
0uA＜IOUT＜150mA
1.0
Consumption
Normal (IOUT=0mA)
70
Current
OFF
1
uA
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.
Table 7-1 LDO1/2 Electrical Characteristics
©2009
Rev. 1.2
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RN5T659 CHARGE PUMP FOR WHITE LED
7.3 Charge Pump
RN5T659 drives up to 5 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 ceramics.
7.3.1 Block Diagram
1uF
1uF
1uF
VOUT
Charge Pump
@115mA(1x,1.33x,1.5x)
VCCCP
2.2μF
GNDCP
Thermal
Shutdown
Feed Back
Adjust Voltage
DIN1
@23mA
DIN2
@23mA
DIN3
@23mA
Current Driver
DIN4
@23mA
LEDCTL
DIN5
NR
@23mA
5bit DAC
GNDCOM
NR：Noise reduction
GND
Fig 7-2 Charge Pump Circuit Diagram
©2009
Rev. 1.2
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RN5T659 CHARGE PUMP FOR WHITE LED
7.3.2 Backlight LED
For maximized power efficiency, the 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
VOUT = GND
Initial
LED channel enabled
VOUT soft start
VOUT pulled up to VCCCP
1x Mode, LED On
Reset to 1x mode
every sec
Min. DIN_ lower than 230mV.
1.33x Mode
Reset to 1.33x mode
every sec
VOUT = VCCCP-Ro*Iled
DIN_=VOUT-Vf
VOUT = 1.33*VCCCP-Ro*Iled
DIN_=VOUT-Vf
Min. DIN_ lower than 230mV.
1.5x Mode
VOUT = 1.5*VCCCP-Ro*Iled
DIN_=VOUT-Vf
Ro:Output Resistanse
Iled:DIN1-5 LED current
Fig 7-3 Mode Transition Diagram
©2009
Rev. 1.2
Page 10
RN5T659 CHARGE PUMP FOR WHITE LED
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.
Fig 7-4 Ground Unused DIN_pin
7.3.5 Soft-start
RN5T659 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.
©2009
Rev. 1.2
Page 11
RN5T659 CHARGE PUMP FOR WHITE LED
7.3.6 Luminance Control
RN5T659 charge pump drives 5 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.
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 the LEDCTL pin longer than 1ms turns off LED.
Luminance
Count value
OFF⇒ON(23mA)
22mA
20mA
19.5mA
19mA
18mA
17mA
16mA
15mA
14.5mA
13mA
12.5mA
11mA
10mA
9mA
8.5mA
8mA
7mA
6.5mA
6mA
5.5mA
5mA
4.5mA
4mA
3.5mA
3mA
2.5mA
2mA
1.5mA
1mA
0.5mA
0.25mA
23mA
…
0 (00h)
1 (01h)
2 (02h)
3 (03h)
4 (04h)
5 (05h)
6 (06h)
7 (07h)
8 (08h)
9 (09h)
10 (0Ah)
11 (0Bh)
12 (0Ch)
13 (0Dh)
14 (0Eh)
15 (0Fh)
16 (10h)
17 (11h)
18 (12h)
19 (13h)
20 (14h)
21 (15h)
22 (16h)
23 (17h)
24 (18h)
25 (19h)
26 (1Ah)
27 (1Bh)
28 (1Ch)
29 (1Dh)
30 (1Eh)
31 (1Fh)
32 (20h)
…
Table 7-2 LED Luminance Control
©2009
Rev. 1.2
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RN5T659 CHARGE PUMP FOR WHITE LED
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
23
2
3
4
1
Soft-start
23
22
20
2
22
20
19.5
ILED
Fig 7-6 Disable LED
7.3.7.2 Initialization of LED
The luminance can be adjusted to initial value by driving LEDCTL pin “H” longer than tRESET but not over tOFF.
(LED remains power-on.)
tRESET
tRESET
2ms (typ)
LEDCTL
Soft-start
1
23
2
22
3
20
4
1
2
22
19.5
19
3
20
2ms (typ)
LEDCTL
Soft-start
19.5
1
23
2
22
3
20
4
19.5
5
19
6
18
7
17
16
ILED
ILED
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.
©2009
Rev. 1.2
Page 13
RN5T659 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
4.5
V
Charge Pump
VIN
Operating Voltage
VCCCP voltage
IOUT
Max. Output current
VCCCP≧3.0V
115
1x ： (VCCCP-Vout)/Iout
0.8
TBD
1.33x ： (1.33xVCCCP-Vout)/Iout
3.2
TBD
1.5x ： (1.5xVCCCP-Vout)/Iout
5.8
TBD
RON
Output resistance
3.0
mA
Ω
FOSC
Switching Frequency
-
1.0
MHz
TSOFT
Soft-start time
-
100
us
1x mode
1
1.33X mode
5
1.5x mode
5
Icc
Consumption Current
mA
Iss
Standby consumption current
VCCCP current
ILIM
Current limit
VOUT shorted
120
mA
-
230
mV
-
100
us
23
mA
VTH1
VTIM
1x to 1.33x transition threshold
1.33x to 1.5x transition threshold
1x to 1.3x transition time
1.33x to 1.5x transition time
5
uA
LED Driver
Isink
Maximum Sink Current
Each DIN1-5
ACC
LED current accuracy
Setting DATA Max , DIN*=0.23V
-5
5
%
IMAT *1
LED current matching
Setting DATA Max ,Vfdiff<0.4V
-2
2
%
VDrop
Current Regulator Dropout
Setting DATA Max
230
mV
ILEAK
DIN1-5 leakage in shutdown
-
0.01
uA
Table 7-3 Charge Pump Electrical Characteristics
Note*1: Matching is defined ( Iave - Iled ) / Iave. Iave means average LED current, respectively.
Matching is defined without Vf voltage difference between channels.
Iave = ( Iled1 + Iled2 + Iled3 + Iled4 + Iled5 ) / 5
7.4 UVLO (Under Voltage Lock Out)
Unless otherwise specified, Ta=25℃
Symbol
Parameter
Condition
VRelease
Under voltage lock out threshold
VCCVIN rising
VDetect
Under voltage lock out threshold
VCCVIN falling
VHYS
UVLO Hysteresis
-
Min
Typ
Max
2.25
2.05
2.20
50
Units
V
2.35
V
mV
Table 7-4 UVLO Electrical Characteristics
©2009
Rev. 1.2
Page 14
RN5T659 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, RN5T659 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
TDET
Detected Temperature
-
140
℃
TRET
Return Temperature
-
110
℃
Icc
Consumption Current
-
10
uA
Table 7-5 Thermal Shutdown Electrical Characteristics
©2009
Rev. 1.2
Page 15
RN5T659 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
-0.3～6.0
V
Vin
Input Voltage Range
All Input Pins
-0.3～VCC*+0.3
V
Package
Mounted on Board,
Allowable Dissipation
Ta =70℃
TBD
mW
Storage Temperature
-
-55～+125
℃
PD
Tstg
Table 8-1 Absolute Maximum Ratings
8.2 Recommendation of Operation Conditions
Symbol
Parameter
VCC_Op
Power Supply Voltage
Condition
Battery Voltage Input Pins
(Operation Conditions)
Min
Typ
Max
Units
2.7
3.6
4.5
V
3.0
3.6
4.5
V
85
℃
Max
Units
Battery Voltage Input Pins
VCC_Rec
Power Supply Voltage
(Recommendation of
Operation Conditions)
Ta
Temp. of Operation
-
-40
Table 8-2 Recommendation of Operation Conditions
8.3 DC Characteristics
Unless otherwise specified, VCCCOM=3.6V, Ta=25℃
Symbol
Parameter
Condition
Min
Vih
“H” Input Voltage
-
1.6
Vil
“L” Input Voltage
-
IIL1
Input Leakage Current 1
VCCCOM
Ishut
Shut-down Consumption
Current
LDOCTL=LEDCTL=”L”
Typ
V
-3
1
0.4
V
3
uA
uA
Table 8-3 DC Characteristics
©2009
Rev. 1.2
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RN5T659 CHARGE PUMP FOR WHITE LED
9. Package Information
©2009
Rev. 1.2
Page 17