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SP7683
Four Channel Charge Pump Regulator LED Driver
FEATURES 2.7V to 5.5V Input Voltage Range Up to 4 LEDS with matching currents LEDs can be Driven from the Charge Pump Output 1X and 1.5X Mode Charge Pump High Efficiency Operation 1.2 MHz Switching Frequency Programable LED Drive Capabliity PWM Dimming Control Low 0.5A Shutdown Current Soft-Start Limits Inrush Current Output Overvoltage Protection Thermal Shutdown Protection QFN (4mm x 4mm) package
LED2 EN/ PWM
14
LED1
16
15
13 12 FB
ISET
On/Off LED3 LED4
1 2 3 4
SP7683
4x4 mm 16 Pin QFN
C2N
11 VMODE 10 VIN 9 C1P 8
5
6
7
C1N
Now Available in Lead Free Packaging
APPLICATIONS Smart Phones Cell Phones PDA's Digital Cameras MP3 Players Other Portables
DESCRIPTION The SP7683 is high efficiency Charge Pump which regulates up to four white LEDs with matching current. Based on the supply headroom available for the four precision current sinks, SP7683 automatically switches between 1X and 1.5X modes. The part powers up in 1X mode, with low quiescent current of 70uA (typ) and remains in 1X mode as long as the LED current has not decreased by more than 0.5%. If the current decreases, then it switches into 1.5X mode where it regulates the lowest of the LED cathode voltages to 0.1V. Other features include soft-start, over current protection, overvoltage protection and thermal shutdown at 140C. Offered in 4X4 16 pin QFN. TYPICAL APPLICATION SCHEMATIC
D1 D2 D3 D4
R10 100k U1 SP7683 EN
15 16 3 4
R1 50k - 200k
(R)
R
SET
Vin C1 1uF
R4 270k
R2 1M
14 2 10 11
R3 100k R9 100k C3 0.1uF
SP7683
9 5 6 13
7 1 12 8
R5 10k
C2 1uF
GND LED_EN C4 1uF
C5 1uF
Date: 12/21/04
SP7683 Four Channel Charge Pump LED Driver
(c) Copyright 2004 Sipex Corporation
1
VOUT
GND
C2P
ABSOLUTE MAXIMUM RATINGS
These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.
ISET Voltage to GND.....................................................0.5V IN, OUT, EN1, EN2 to GND................................-0.3V to 6V SET, LED1, LED2, LED3, LED4 to GND -0.3V to IN+0.3V C1N, C2N to GND...........................................-0.3 to IN+1V C1P, C2P to GND - 0.3V to greater than IN+1 or OUT+1V
OUT Short Circuit to GND.........................Continious Storage Temperature ........................-65C to 150C Operating Temperature......................-40C to +85C Lead Temperature (Soldering, 10 sec)............300C
ELECTRICAL CHARACTERISTICS
Unless otherwise specified: VIN = 3.6V, MODE = 0V, ILX = 0mA, TA = -40C to +85C, typical values at 27 unless otherwise noted.
PARAMETER Input Voltage Quiescent Current Shutdown Current Maximum Load Current VOUT Turn-on TIme Output Current Multiplication Ratio (Note 1) LED Current Matching LED Cathode Voltage Current in OFF Mode Oscillator Frequency FB Reference Voltage FB Pin Current Output Resistance
MIN 2.7
TYP
MAX 5.5
UNITS V mA A mA
CONDITIONS
.5 .5 200 250 140 -3 200 0.8 0.5 0.01 .7 .277 1.2 .310 0.01 8 3
3 1.5
VIN = 3V - 5.5V, VOUT = 3.6V, IOUT = 100A VEN/PWM = 0V, VIN = 5.5V VIN = 4.2V, VOUT = 3.6V FB within 90% regulation 1.5X Mode, VOUT = 3.6, IOUT = 100A ISET = 100A, VLED = .3V
500 260 3
s
% V
Any 2 LEDs LEDs D1-D4 VEN = 0V VIN = 2.7V - 5.5V IOUT = 20mA, VOUT = 3.6V, 1.5X MODE VFB = 1V 1.5X MODE, 100mA load
1 1.5 .342 0.5 15
A MHz V A Ohms
7 1.5 V mV 0.5 A V 0.4 V A
1X MODE, 100mA load VIN falling
VMODE Threshold Voltage VMODE Hysteresis VMODE Pin Current ENABLE/PWM Logic High ENABLE/PWM Logic Low Enable/ PWM Pin Current
1
1.25 30 0.01
VMODE = 1.25V
1.6
0.01
0.5
VEN / PWM = 4.2V
Note 1: Output current Multiplication Ratio (ILED/ISET) is not linear. For actual ratio and ILED please refer to typical performance characteristics @ page 4 and page 5 of SP7614 datasheet.
Date: 12/21/04
SP7683 Four Channel Charge Pump LED Driver
(c) Copyright 2004 Sipex Corporation
2
ELECTRICAL CHARACTERISTICS
Unless otherwise specified: VIN =3.6V, MODE=0V, ILX=omA, TA =-40C to +85C, typical values at 27 unless otherwise noted.
PARAMETER Min ON/OFF "On Voltage" Logic High (Note 2) Max ON/OFF "Off Voltage" Logic Low (Note 2)
MIN 3
TYP
MAX
UNITS V
CONDITIONS
0.5
V
Note 2: "ON" is VON/OFF where ILED1 > 20mA @ VLED1 = 0.3V. "OFF" is VON/OFF where ILED1 < 1A @ VLED1 > 0.3V.
PIN DESCRIPTION
PIN # 1 2 3 PIN NAME ISET ON/OFF LED3 DESCRIPTION A pull up resistor attached between VOUT and this pin sets the output current by the relationship. ILED = 200(VOUT - VISET) / RSET LED ON/OFF control (LED1 - LED4). Cathode Connection for LED4. In 1.5X Mode the charge pump regulates VOUT so that the lowest of LED1, LED2, LED3, and LED4 voltages is 150mV. Connect to VOUT if not used. Cathode Connection for LED3. In 1.5X Mode the charge pump regulates VOUT so that the lowest of LED1, LED2, LED3, and LED4 voltages is 150mV. Connect to VOUT if not used. Flying Capacitor 1 Negative terminal. Flying Capacitor 2 Positive Terminal Output. Drives the anodes of all LEDs. Bypass to GND with a 1F capacitor. High Impedance Shutdown Ground Connection Flying Capacitor 1 Postive terminal. Supply voltage input. Bypass with a 1F ceramic capacitor to GND Charge pump mode program pin. When Vmode is greater than 1.25V, a X1 charge pump is used. Otherwise, charge pump switches to X1.5 mode. A voltage divider shown in typical application circuit programs the Vin threshold for charge pump mode switching. This is the feedback pin for output current or voltage regulation. The voltage of this pin is compared with an internal 306mV reference. Flying Capacitor 2 Negative terminal. Enable/PWM dimming control input. Cathode Connection for LED1. In 1.5X Mode the charge pump regulates VOUT so that the lowest of LED1, LED2, LED3, and LED4 voltages is 150mV. Connect to VOUT if not used. Cathode Connection for LED2. In 1.5X Mode the charge pump regulates VOUT so that the lowest of LED1, LED2, LED3, and LED4 voltages is 150mV. Connect to VOUT if not used.
4 5 6 7 8 9 10
LED4 C1N C2P VOUT GND C1P VIN
11
VMODE
12 13 14 15
FB C2N EN/PWM LED1
16
LED2
Date: 12/21/04
SP7683 Four Channel Charge Pump LED Driver
(c) Copyright 2004 Sipex Corporation
3
BLOCK DIAGRAM
VIN EN/PWM Voltage Reference
1.25V
600 kHz Clock Manager
C1P Start-up and Charge Pump Switches C1N C2P C2N VOUT
VMODE
MODE COMP
Mode Control
306mV
FB Logic Control
VOUT COMP GND
ON/OFF
LDO Current Regulator
LED1
LED2 LED3 LED4
Date: 12/21/04
SP7683 Four Channel Charge Pump LED Driver
(c) Copyright 2004 Sipex Corporation
4
CIRCUIT DESCRIPTION The SP7683 is comprised of two stages. First is a regulated change pump to convert the input voltage VIN into a stable output voltage or current depending on the mode used. The second stage is a low dropout current matching regulator that provides stable identical currents in all four channels to drive LED1 - LED4. The first stage can drive an additional four LEDs that are connected in parallel to the VOUT pin. It is recommended to use resistors in series with these additional diodes for current matching. The SP7683 provides dimming control for the LEDs, with a constant ratio of brightness between them. It can also be used to turn off the LEDs completely. The Charge Pump The regulated charge pump can operate in two modes 1X VIN and 1.5X VIN to optimize efficiency over the entire battery voltage range. The input voltage trip point at which the charge pump will automatically switch from a 1X mode to 1.5X mode is defined by an external voltage divider connected to VMODE pin. Cycle-by-cycle regulation ensures that no mode change occurs during a switching cycle. To achieve better efficiency it is recommended that the VIN_TRIP is set at VIN_TRIP = VF + 0.31 + MILED *ROUT where VF is the LED forward voltage and (M) is the number of LEDs connected to VOUT . ROUT is the output resistance. ILED is the current per LED. The charge pump may be configured in voltage mode or as a current source. When used as a voltage source the output voltage is determined by an external resistive divider connected to FB pin as: VOUT = (1+R10/R5)*VFB (see Figure 2) where VFB = 0.31V. When used as a current source the current in one single LED (D5 - D8) may be set by series resistor RS as ILED = VFB / RS. The current in the remaining LEDs will track based on the ballast resistors. Three-wire LED modules with internal series resistors can also be driven in this way. The flying capacitors C1 an C2 of the charge pump control the tade-off between the output voltage ripple and the output current capability. Decreasing the flying capacitors will reduce the output voltage ripple because less charge will be delivered to the output capacitor. However, smaller flying capacitors lead to larger output resistance, thus decreasing the output current handling capability and circuit efficiency. We recommend using ceramic capacitors in the range of 1F 4.7F with low ESR, which helps reduce peak-to-peak output ripple and reduce high frequency noise spikes. Dimming control can be achieved by applying a PWM control signal to the EN/PWM pin. The brightness of the LEDs is controlled by varying the duty cycle of the PWM signal. PWM repetition rate from 60Hz - 700Hz. A repetition rate of at least 60Hz is required to prevent visible flickering. Applying a logic low signal to EN/PWM control input turns of the device resulting in supply current below 1A and high impedance state of the VOUT pin.
Date: 12/21/04
SP7683 Four Channel Charge Pump LED Driver
(c) Copyright 2004 Sipex Corporation
5
CIRCUIT DESCRIPTION The Low Dropout Regulator The low dropout regulator provides matched currents into four LEDs. The current in the LED can be programmed by an external resistor connected between the VOUT and ISET pins. ILED = 200*(VOUT - 0.5)/RSET where the 200 is the Output Current Multiplying Ratio and 0.5 is ISET voltage value. Board Layout and Grounding To obtain the best performance from the SP7683, a printed circuit board with ground plane is required. High quality, low series resistance ceramic 0.1F bypass capacitors should be used at the VIN and VOUT pins (pin 10 and 7). These capacitors and flying capacitors C1 and C2 must be located as close to the part as possible. The traces connecting the pins to these capacitors should be made as short and wide as possible.
D1 D2 D3 D4 D5 D6 D7 D8
U1 SP7683 EN
15 16 3 4
R1 50k - 200k
(R)
Vin C1 1uF
R4 270k
R2 1M
14 2 10 11
R3 100k R9 100k C3 0.1uF
SP7683
7 1 12 8
R5 20
9 5 6 13
R6
R7
R8
C2 1uF
GND LED_EN C4 1uF
C5 1uF
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
U1 SP7683 EN
15 16 3 4
R1 50k - 200k
(R)
Vin C1 1uF
R5 270k
R3 1M
14 2 10 11
7
R2 Q1 R6 C2 1uF
R4 100k C3 0.1uF
SP7683
1 12 8
9 5 6 13
Q2 R7 100k GND R8 LED_EN C4 1uF C5 1uF
Date: 12/21/04
SP7683 Four Channel Charge Pump LED Driver
(c) Copyright 2004 Sipex Corporation
6
PACKAGE: 16 PIN QFN
D
E
4X A SEATING PLANE A1
O
A2
A3
D2
16 Pin QFN JEDEC MO-220 VGGC-4 Variation MIN NOM MAX SYMBOL A 0.8 0.9 1 A1 0 0.02 0.05 A2 0 0.65 1 0.20 REF A3 4.00 BSC D 4.00 BSC E E2 7.4 7.8 8.2 D2 2.2 2.4 2.6 E2 2.2 2.4 2.6 L 0.45 0.55 0.65 K 0.2 b 0.25 0.3 0.35 e 0.65 BSC Note: Dimensions in (mm)
NX L
E2
NX K e NX b
16 PIN QFN
Date: 12/21/04
SP7683 Four Channel Charge Pump LED Driver
(c) Copyright 2004 Sipex Corporation
7
ORDERING INFORMATION
Part Number Operating Temperature Range Package Type
SP7683ER .................................................. -40C to +85C ............................................ 16 Pin 4 x 4mm QFN SP7683ER/TR ............................................ -40C to +85C ............................................ 16 Pin 4 x 4mm QFN Available in lead free packaging. To order add "-L" suffix to part number. Example: SP7683ER/TR = standard; SP7683ER-L/TR = lead free /TR = Tape and Reel Pack quantity is 2500 for QFN.
CLICK HERE TO ORDER SAMPLES
Corporation
ANALOG EXCELLENCE
Sipex Corporation Headquarters and Sales Office 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.
Date: 12/21/04
SP7683 Four Channel Charge Pump LED Driver
(c) Copyright 2004 Sipex Corporation
8

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