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Preliminary
RT9903B
4 Channel DC/DC Converters IC with High-Efficiency Step-Up
General Description
The RT9903B is a complete power-supply solution for digital still cameras and other hand-held devices. It integrates a high-efficiency fours step-up DC-DC converters and a charge pump. The two Step-up DC-DC converters (CH1,CH2) accept inputs from 1.5V to 5.5V and regulate a resistoradjustable output up to 17V. One Step-up DC-DC converter (CH3) can be regarded as white LED Driver, which reference voltage is 0.2V and have OVP function. One step-up DC-DC converter (CH4) regulate a resistoradjustable output up 5V. An adjustable operating frequency (up to 1.4MHz) is utilized to get optimum size, cost, and efficiency. RT9903B is available in VQFN-24L 4x4 package. Each DC-DC converters have independent shutdown inputs.
Features
Two step-up DC-DC Converters (CH1, CH2) HV Internal Switches 50mA Load Current One Step-up DC-DC Converter (CH3) 0.2V Reference Voltage HV Internal Switches LED Brightness Dimming Control Over Voltage Protection One Step-up DC-DC Converter (CH4) External Switches External Current Limit Setting Up to 1.4MHz Switching Frequency 1A Supply Current in Shutdown Mode External Compensation Network for All Converters Programmable Soft Start Function (CH1, CH2, CH3, CH4) Independent Enable Pin to Shutdown Each Channel 24-Lead VQFN Package RoHS Compliant and 100% Lead (Pb)-Free
Applications
Digital Still Camera PDAs Portable Device
Pin Configurations
(TOP VIEW)
COMP2 AGND COMP1
19 18 17 16
Ordering Information
RT9903B Package Type QV : VQFN-24L 4x4 (V-Type) Operating Temperature Range P : Pb Free with Commercial Standard G : Green (Halogen Free with Commercial Standard)
NC PGND PGND RT EXT4 CS4
1 2 3 4 5 6 7
FB2
24
23
22
21
FB1
20
LX2
LX1 VDD PGND EN4 EN2 EN1
Note : Richtek Pb-free and Green products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. 100% matte tin (Sn) plating.
GND
15 14 25 13
8
9
10
11
12
FB4
COMP4
FB3
COMP3
LX3
VQFN-24L 4x4
Marking Information
For marking information, contact our sales representative directly or through a Richtek distributor located in your area, otherwise visit our website for detail.
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EN3
RT9903B
Typical Application Circuit
2-AA Battery 1.8V to 3.2V
Preliminary
VBATT
C1 10uF D1 SS0520 C2 1uF
L1 4.7uH 11 LX 3 R1 4 RT
WLED (12V)
17 VDD
C15 4.7uF
C16 10uF L3 4.7uH D3 SS0520 R9 2.2M C17 1nF R10 200k C18 10uF +12V (+LCD)
LX1
18
R15 10
V C3 C4 BATT 10uF 10uF
21 AGND 16 PGND 9 FB RT9903B 3
FB1
20 VBATT C19 10uF
L4 4.7uH D4 SS0520 R11 5.1M R12 360k C21 to C23 10uFx3 C20 1nF
3.3V_Motor R2 300k R3 130k
D2 SS0520 C9 1nF
L2 4.7uH R4 10k 6 CS4 Q1 Si2302 7 FB4 EN1 EN2 EN3 EN4 COMP1 COMP2 COMP3 COMP4 5 EXT4
LX2
24
+15V (+CCD)
C5 to C8 10uFx4
FB2 22
Chip Enable
13 14 12 15 19 23 10 8
D5 C24 BAT54WSPT 2.2uF R13 8.2k NC PGND 1 2, 3 NC D6 ZENER Diode C25 1uF
-6V (+CCD) C26 10uF
C11 500pF R5 1.2k C10 4.7nF R6 R7 2.2k 1.2k C12 C13
R8 2.7k C14 6.8nF 56nF 4.7nF
If -CCD = -6V, D6 = 5.6V_ZD If -CCD = -8V, D6 = 3.6V_ZD
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DS9903B-07 August 2007
Preliminary
V_3.3V VBATT C1 10uF D1 SS0520 C2 1uF C15 4.7uF C16 10uF L3 4.7uH D3 SS0520 R9 2.2M C17 1nF R10 200k C18 10uF
RT9903B
L1 4.7uH 11 LX3 R1 4
WLED (12V)
17 VDD
LX1 RT FB1
18
+12V (+LCD)
21 AGND 16 PGND 9 FB3 R15 10 C3 C4 10uF 10uF VBATT L2 4.7uH 3.3V_Motor C5 to C8 10uFx4 R2 300k R3 130k Chip Enable D2 SS0520 C9 1nF R4 10k 6 Q1 Si2302 7 13 14 12 15 19 23 10 8 R6 R7 2.2k 1.2k C12 C13 R8 2.7k C14 FB4 EN1 EN2 EN3 EN4 COMP1 COMP2 COMP3 COMP4 5 RT9903B
20 VBATT C19 10uF
L4 4.7uH D4 SS0520 R11 5.1M R12 360k D5 C24 BAT54WSPT 2.2uF R13 8.2k -6V (+CCD) C26 10uF C21 to C23 10uFx3 C20 1nF
LX2 CS4 EXT4
24
+15V (+CCD)
FB2 22
NC PGND
1 2, 3
NC D6 ZENER Diode
C11 500pF R5 1.2k C10 4.7nF
C25 1uF
If -CCD = -6V, D6 = 5.6V_ZD If -CCD = -8V, D6 = 3.6V_ZD
6.8nF 56nF 4.7nF
Function Block Diagram
COMP1 EN1 LX1 FB1 COMP2 EN2 LX2 FB2
VDD
CH1 V-Mode Step-Up PWM
+
CH2 V-Mode Step-Up PWM VREF 1V CH4 C-Mode Step-Up PWM 10uA
+ Oscillator Soft Start RT
CH3 C-Mode Step-Up PWM AGND
+ -
Thermal Protection
-
+
VREF 0.2V
COMP3
EN3 LX3
FB3
COMP4 EN4 EXT4 CS4
FB4
PGND (Exposed Pad)
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RT9903B
Functional Pin Description
Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Pin Name NC PGND PGND RT EXT4 CS4 FB4 COMP4 FB3 COMP3 LX3 EN3 EN1 EN2 EN4 PGND VDD LX1 COMP1 FB1 AGND FB2 COMP2 LX2 No Connection. Power Ground. Power Ground.
Preliminary
Pin Function
Frequency Setting Resistor Connection Pin. CH4 External Power Switch. CH4 Current Sense Input Pin. CH4 Feedback Input. CH4 Feedback Compensation Pin. CH3 Feedback Input. CH3 Feedback Compensation Pin. CH3 Switch Node. CH3 Enable Input Pin. CH1 Enable Input Pin. CH2 Enable Input Pin CH4 Enable Input Pin. Power Ground. Power Input Pin. CH1 Switch Node. CH1 Feedback Compensation Pin. CH1 Feedback Input. Analog Ground. CH2 Feedback Input. CH2 Feedback Compensation Pin. CH2 Switch Node. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation.
Exposed Pad (25) GND
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Preliminary Absolute Maximum Ratings
(Note 1)
RT9903B
-0.3 to 7V -0.3V to 20V -0.3V to 7V
1.923W 52C/W 260C -40C to 85C 0C to 125C -65C to 150C
Supply Input Voltage (VDD) --------------------------------------------------------------------------------------------LX1, LX2, LX3 Pins ------------------------------------------------------------------------------------------------------Other I/O Pin Voltage ---------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25C VQFN-24L 4x4 -----------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 3) VQFN-24L 4x4, JA ------------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) -----------------------------------------------------------------------------Operation Temperature Range ----------------------------------------------------------------------------------------Junction Temperature Range ------------------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------
Recommended Operating Conditions
(Note 2)
Maximum Output Voltage Setting ( VOUT1 and VOUT2 ) ---------------------------------------------------------- 17V Dimming Control Frequency Range, CH3 -------------------------------------------------------------------------- 200Hz to 900Hz
Electrical Characteristics
(VDD =3.3V, TA = 25C, unless otherwise specification)
Parameter Supply Voltage VDD Operating Voltage VDD Start-up Voltage VDD Over Voltage Protection Supply Current Shutdown Supply Current CH1 DC/DC Converter Supply Current
Symbol VVDD
Test Condition VDD Pin Voltage VDD Pin Voltage
Min 2.4 1.5 6 --
Typ ---0.01
Max 5.5 --1
Units V V V A
VDD(OVP) VDD Pin Voltage IOFF VDD = 3.6V, VEN1 to 4 = 0V VVDD =3.6V, IVDD1 VFB1 = VREF + 0.15V VEN1 = 3.3V, VEN2 = 0V, VEN3 = 0V, VEN4 = 0V VVDD = 3.6V,
--
200
250
A
CH2 DC/DC Converter Supply Current
IVDD2
VFB2 = VREF + 0.15V VEN1 = 0V, VEN2 = 3.3V, VEN3 = 0V, VEN4 = 0V VVDD = 3.6V,
--
210
260
A
CH3 DC/DC Converter Supply Current
IVDD3
VFB3 = VREF + 0.15V VEN1 = 0V, VEN2 = 0V, VEN3 = 3.3V, VEN4 = 0V VVDD = 3.6V,
--
250
300
A
CH4 DC/DC Converter Supply Current
IVDD4
VFB4 = VREF + 0.15V VEN1 = 0V, VEN2 = 0V, VEN3 = 0V, VEN4 = 3.3V
--
200
250
A
To be continued
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RT9903B
Parameter Oscillator Free Running Frequency CH1, CH2, CH3 Maximum Duty Cycle CH4 Maximum Duty Cycle Reference Voltage (CH1, CH2, CH3, CH4) Feedback Reference Voltage Feedback Reference Voltage Error Amplifier GM Compensation Source Current Compensation Sink Current Power Switch CH1 On Resistance of MOSFET CH1 Current Limitation CH2 On Resistance of MOSFET CH2 Current Limitation CH3 On Resistance of MOSFET CH3 Current Limitation CH4 Over Current Threshold Voltage CH4 On Resistance of N-MOSFET CH4 On Resistance of P-MOSFET Control
Preliminary
Symbol FOSC DMAX1,2,3 DMAX4 VFB1, 2, 4 CH1, CH2, CH4 VFB3 CH3 FB1 = COMP Test Condition RT = Open Min 400 93 75 0.98 0.18 ---RDS1(ON) N-MOSFET, VDD = 3.3V RDS2(ON) N-MOSFET, VDD = 3.3V RDS3(ON) N-MOSFET, VDD = 3.3V -0.7 -0.7 -0.7 0.3 3 -VVDDM = 3.3V VVDDM = 3.3V ICS4 TSD -0.4 8 -Typ 500 95 80 1 0.2 200 22 22 0.6 -0.6 -0.6 -0.4 6 20 0.8 0.8 10 180 Max Units 600 -85 1.02 0.22 ---------0.5 9 -1.3 -12 -kHz % % V V s A A A A A V V V A C
EN1, EN2, EN3, EN4 Input High Level Threshold EN1, EN2, EN3, EN4 Input Low Level Threshold External Current Setting (CH4) CS4 Sourcing Current Thermal Protection Thermal Shutdown
Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2. The device is not guaranteed to function outside its operating conditions. Note 3. JA is measured in the natural convection at T A = 25C on a low effective thermal conductivity test board of JEDEC 51-3 thermal measurement standard. Note 4. Pull low EN1, EN2 and EN4 when they are not enabled. EN3 pin is automatically pulled low when not enabled.
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Preliminary Typical Operating Characteristics
CH1 Efficiency vs. Output Current
100 95 90 85
RT9903B
VLX1 & Output Ripple
VOUT = 12V VIN = 3.8V VIN = 4.5V
Efficiency (%)
VIN = 2.5V
75 70 65 0 5 10 15
VIN = 3V
Output Ripple (50mV/Div)
30 35 40 45 50
80
LX1 (5V/Div)
VBAT = 2.5V, VDD = 3.3V, @IOUT = 30mA
20
25
Time (1us/Div)
Output Current (mA)
VLX1 & Output Ripple
VLX1 & Output Ripple
LX1 (5V/Div)
Output Ripple (50mV/Div)
VBAT = 3V, VDD = 3.3V, @IOUT = 30mA
Output Ripple (50mV/Div)
LX1 (5V/Div)
VBAT = 3.8V, VDD = 3.3V, @IOUT = 30mA
Time (1us/Div)
Time (1us/Div)
VLX1 & Output Ripple
100 95
CH2 Efficiency vs. Output Current
VOUT = 15V
LX1 (5V/Div)
Efficiency (%)
90
VIN = 3.8V VIN = 4.5V
85 80 75
Output Ripple (50mV/Div)
VIN = 2.5V VIN = 3V
VBAT = 4.2V, VDD = 3.3V, @IOUT = 30mA
70 0 5 10 15 20 25 30
Time (1us/Div)
Output Current (mA)
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RT9903B
VLX2 & Output Ripple
Preliminary
VLX2 & Output Ripple
LX2 (5V/Div)
Output Ripple (20mV/Div)
VBAT = 2.5V, VDD = 3.3V, @IOUT = 30mA
Output Ripple (20mV/Div)
LX2 (5V/Div)
VBAT = 3V, VDD = 3.3V, @IOUT = 30mA
Time (1us/Div)
Time (1us/Div)
VLX2 & Output Ripple
VLX2 & Output Ripple
LX2 (5V/Div)
Output Ripple (20mV/Div)
VBAT = 3.8V, VDD = 3.3V, @IOUT = 30mA
Output Ripple (20mV/Div)
LX2 (5V/Div)
VBAT = 4.2V, VDD = 3.3V, @IOUT = 30mA
Time (1us/Div)
Time (1us/Div)
CH3 Efficiency vs. Input Voltage
100
VLX3 & Output Ripple
4 series WLED, ILED = 20mA
Efficiency (%)
90
80
Output Ripple (100mV/Div)
2 2.4 2.8 3.2 3.6 4 4.4
85
LX3 (5V/Div)
VBAT = 2.5V, VDD = 3.3V, @IOUT = 20mA
95
75
Input Voltage (V)
Time (1us/Div)
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Preliminary
RT9903B
VLX3 & Output Ripple
LX3 (5V/Div) LX3 (5V/Div)
VLX3 & Output Ripple
Output Ripple (100mV/Div)
VBAT = 3V, VDD = 3.3V, @IOUT = 20mA
Output Ripple (100mV/Div)
VBAT = 3.8V, VDD = 3.3V, @IOUT = 20mA
Time (1us/Div)
Time (1us/Div)
VLX3 & Output Ripple
100
CH4 Efficiency vs. Output Current
VOUT = 3.3V
LX3 (5V/Div)
95
Efficiency (%)
VIN = 3V
90
Output Ripple (100mV/Div)
85
VIN = 2V
VIN = 2.5V
VBAT = 4.2V, VDD = 3.3V, @IOUT = 20mA
80 1 10 100 1000
Time (1us/Div)
Output Current (mA)
VLX4 & Output Ripple
LX4 (2V/Div) LX4 (2V/Div)
VLX4 & Output Ripple
Output Ripple (20mV/Div)
VBAT = 2V, VDD = 3.3V, @IOUT = 100mA
Output Ripple (20mV/Div)
VBAT = 2V, VDD = 3.3V, @IOUT = 350mA
Time (1us/Div)
Time (1us/Div)
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RT9903B
Preliminary
VLX4 & Output Ripple
LX4 (2V/Div) LX4 (2V/Div)
VLX4 & Output Ripple
Output Ripple (20mV/Div)
VBAT = 2.5V, VDD = 3.3V, @IOUT = 100mA
Output Ripple (20mV/Div)
VBAT = 2.5V, VDD = 3.3V, @IOUT = 350mA
Time (1us/Div)
Time (1us/Div)
VLX4 & Output Ripple
LX4 (2V/Div) LX4 (2V/Div)
VLX4 & Output Ripple
Output Ripple (20mV/Div)
VBAT = 3V, VDD = 3.3V, @IOUT = 100mA
Output Ripple (20mV/Div)
VBAT = 3V, VDD = 3.3V, @IOUT = 350mA
Time (1us/Div)
Time (1us/Div)
CH4 Load Transient Response
Output Ripple (200mV/Div) Output Ripple (100mV/Div)
CH4 Load Transient Response
Output Current (200mA/Div)
VBAT = 2V, VDD = 3.3V, @IOUT = 100mA to 350mA
Output Current (200mA/Div)
VBAT = 2.5V, VDD = 3.3V, @IOUT = 100mA to 350mA
Time (1ms/Div)
Time (1ms/Div)
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Preliminary
RT9903B
Frequency vs. RRT Resistor
2500
CH4 Load Transient Response
Output Ripple (100mV/Div)
2000
Frequency (kHz)1
VBAT = 3V, VDD = 3.3V, @IOUT = 100mA to 350mA
1500
Output Current (200mA/Div)
1000
500
0 0 50 100 150 200 250 300
Time (1ms/Div)
RRT (k)
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RT9903B
Application Information
Preliminary
Step-up (Boost) DC/DC Converter (CH1) The channel (CH1) is a step-up voltage-mode DC/DC PWM converter with built-in internal power MOS and external schottky diode. Output voltage is regulated and adjustable up to 17V. This channel is designed to supply several tens mA current. The maximum duty of the constant frequency is 96% for this channel to prevent high input current drawn from input.
The RT9903B is a four-Channel DC/DC converter for digital still cameras and other hand-held device. The four channels DC/DC converters are as follows: CH1: Step-up, asynchronous voltage mode DC/DC converter with an internal power MOSFET, current limit protection, and over voltage protection. This channel is designed to supply output voltage from 3.3V to 17V. CH2: Step-up, asynchronous voltage mode DC/DC converter with an internal power MOSFET, current limit protection, and over voltage protection. This channel is designed to supply output voltage from 3.3V to 17V. CH3: Step-up, asynchronous current mode DC/DC converter with an internal power MOSFET, current limit protection, and over voltage protection. This channel is designed to light 2~4 WLEDs with constant current regulation, and the lightness can be dimming-controlled by the duty of EN3 pin. CH4: Step-up, asynchronous current mode DC/DC converter with current limit protection. This channel is designed to drive external N-MOS switch for steppingup voltage. Soft-Start CH1, CH2, and CH4 can be soft-started individually every time when the channel is enabled. Soft-start is achieved by ramping up the PWM duty from very small to normal operation. The ramping up PWM duty is achieved by sourcing 1uA from error amplifier to the compensation capacitor. When the output voltage is regulated, the PWM duty enters the normal operation, and the error amplifier can sink and source up to 22uA. The soft-start time is set by the following formula:
TSOFT-START = (1V - 1uA x RCOMP) x CCOMP 1uA
Protection
Current Limit The current of NMOS is sensed cycle by cycle to prevent over current. When over current limit, then the NMOS is off. This state is latched and then reset automatically at next clock cycle. Over Voltage The over voltage protection prevents LX1 voltage going too high. The over-voltage is detected by the junction leakage and the threshold value is around 22V. This channel is latched shut down when OVP occurs, and can be reset by toggling EN1. Step-up (Boost) DC/DC Converter (CH2) The channel (CH2) is a step-up voltage-mode DC/DC PWM converter with built-in internal power MOS and external schottky diode. Output voltage is regulated and adjustable up to 17V. This channel is designed to supply several tens mA current. The maximum duty of the constant frequency is 96% for this channel to prevent high input current drawn from input.
Protection
Current Limit The current of NMOS is sensed cycle by cycle to prevent over current. When over current limit, then the NMOS is off. This state is latched and then reset automatically at next clock cycle.
RCOMP and CCOMP are compensation components. Oscillator The internal oscillator synchronizes CH1, CH2, CH3 and CH4 PWM operation frequency. The operation frequency is set by a resistor between RT pin to ground, ranging from 500kHz to 1.4MHz.
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DS9903B-07 August 2007
Preliminary
Over Voltage The over voltage protection prevents LX2 voltage going too high. The over-voltage is detected by the junction leakage and the threshold value is around 22V. This channel is not latched shut down when OVP occurs. Step-up (Boost) DC/DC Converter (CH3) The channel (CH3) is a step-up current-mode DC/DC PWM converter with built-in internal power MOS and external schottky diode. This channel is designed to light 2 to 4 WLEDSs with constant current regulation. The lightness of WLED can be dimming-controlled by the duty of EN3 pin. The maximum duty of the constant frequency is 96% for this channel to prevent high input current drawn from input.
RT9903B
Protection
Current Limit The current of NMOS is sensed cycle by cycle to prevent over current. The current is sensed by CS4 pin to determine whether it reaches current limit threshold. When CS4 voltage is higher than 0.4V, the external NMOS is off. This state is latched and then reset automatically at next clock cycle. V(CS4) = 10A x RCS + IInductor x RDC(ON) External_MOS Current Mode Step-up Compensation When the step-up converter operates with continuous inductor current, the right-half-plane zero (RHPZ) appears in the loop-gain frequency response. To ensure the stability, the control-loop gain should crossover at the frequency (crossover frequency fC) much less than that of RHPZ. The inductor (L) and output capacitance (COUT) are chosen first in consideration of performance, size, and cost. The compensation resistor(RC) and capacitor(CC) are then chosen to optimize the control-loop stability. The useful steps are listed below to calculate loop compensation. Step-1 Calculate RHPZ For continuous conduction, the RHPZ is given by
Protection
Current Limit The current of NMOS is sensed cycle by cycle to prevent over current. When over current limit, then the NMOS is off. This state is latched and then reset automatically at next clock cycle. Over Voltage The over voltage protection prevents LX3 voltage going too high. The over-voltage is detected by the junction leakage and the threshold value is around 22V. This channel is latched shut down when OVP occurs, and can be reset by toggling EN3. Step-up (Boost) DC/DC Converter (CH4) The channel (CH4) is a step-up current-mode DC/DC PWM converter to drive external power N-MOS and external schottky diode. At light load, efficiency is enhanced by pulse-skipping mode. In this mode, the external NMOS turns on by a constant pulse width. As loading increased, the converter operates at constant frequency PWM mode. The maximum duty of the constant frequency is 80% for the boost to prevent high input current drawn from input.
fRHPZ =
VOUT (1-D)2 2 L IOUT
Where D is the duty cycle = 1-(VIN / VOUT), L is the inductor value, and ILOAD is the maximum output current. Typical target crossover frequency is 1/6 of RHPZ. For example, if we assume VIN = 1.8V, VOUT = 3.3V, and IOUT = 0.5A, the RLOAD = 6.6. If we select L = 4.7uH, then : fRHPZ = 66kHz Step-2 Calculate CC Choose fC = 10kHz, and then CC is calculated from the simplified loop-gain formula.
Loop gain = Gm x 1 + SRCCC 1 ROUT VFB x x (1-D) x x SCC RCS 1+SROUTCOUT VOUT
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RT9903B
Preliminary
Where Gm is the transconductance of error amplifier, and RCS is the current sense amplifier transresistance. In our design, Gm = 200us, RCS = 0.8V/A, and VFB = 1V, and then CC = 4.34nF from calculation. Choose CC = 4.7nF. Step-3 Calculate RC RC is calculated such that transient droop requirements are met. For example, in our design, if 5% transient droop is allowed, then the error amplifier moves 0.05 x 1V, or 50mV. The error amplifier output drives 50mV x 200us, or 10uA across RC to provide transient gain. We select RCS = 2.7k to meet the requirements. The output capacitor is chosed 40uF to cancel the RC CC zero, and can sustain stable VOUT voltage at heavy load condition. Reference The chip has an internal 1V reference voltage, which is the inputs of the error amplifiers of the CH1, CH2, and CH4 to compare the difference of feedback voltage. The reference voltage of CH3 is 0.2V for WLEDs application. The reference voltage can be set up stably when the supplied power (VDD) is above 1.5V, and EN1 (or EN2, EN3, EN4 either one) goes high. Thermal Protection Thermal protection function is integrated in the chip. When the chip temperature is higher than 180C, the controllers of all channels are shutdown. When the thermal protection is relieved, the chip operates well again.
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DS9903B-07 August 2007
Preliminary Outline Dimension
D2
RT9903B
D
SEE DETAIL A L 1
E
E2
1 2
1 2
e A A3 A1
b
DETAIL A Pin #1 ID and Tie Bar Mark Options Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated.
Symbol A A1 A3 b D D2 E E2 e L
Dimensions In Millimeters Min 0.800 0.000 0.175 0.180 3.950 2.300 3.950 2.300 0.500 0.350 0.450 Max 1.000 0.050 0.250 0.300 4.050 2.750 4.050 2.750
Dimensions In Inches Min 0.031 0.000 0.007 0.007 0.156 0.091 0.156 0.091 0.020 0.014 0.018 Max 0.039 0.002 0.010 0.012 0.159 0.108 0.159 0.108
V-Type 24L QFN 4x4 Package
Richtek Technology Corporation
Headquarter 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611
Richtek Technology Corporation
Taipei Office (Marketing) 8F, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek.com
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