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FAN5336 -- 1.5MHz Boost Regulator with 33V Integrated FET Switch
April 2007
FAN5336
1.5MHz Boost Regulator with 33V Integrated FET Switch
Features
1.5MHz Switching Frequency Low Noise Adjustable Output Voltage Up to 1.5A Peak Switch Current Low Shutdown Current: <1A Cycle-by-Cycle Current Limit Over-Voltage Protection at the Feedback Pin Fixed-Frequency PWM Operation Soft-Start Capability Internal Compensation Thermal Shutdown Excellent Load Regulation: 0.2% Low Ripple 6-Lead 3x3mm MLP
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Description
The FAN5336 is a high-efficiency, low-noise, fixed-frequency PWM, current-mode, DC-DC boost regulator. It is designed for small LCD bias supply and white LED backlight supply applications. Depending on the application, a FAN5336 regulator can output up to 33V at up to 50mA output current. With output voltage up to 21V, the output current can be up to 100mA. FAN5336 can be used for power conversion as low as 9V output voltage. A current-mode control loop has a fast transient response that provides excellent load regulation within 0.2% of output voltage. The FAN5336 switches at fixed 1.5MHz frequency, allowing the use of small, low-cost external components. Constant frequency switching results in low input noise and small output capacitors. FAN5336 provides cycle-by-cycle current limiting up to 1.5A peak current. The FAN5336 may be used to drive a serial flash LED with up to 100mA current at 21V for a maximum of 400ms on-time and 10% duty cycle. A low-EMI mode reduces interference and radiated electromagnetic energy caused by the ringing of the inductor. Additional features include thermal shutdown, over-voltage protection, cycle-by-cycle current limit, low ripple, and soft-start support. The device is available in a 3x3mm 6-lead MLP, 0.8mm thickness package.
Applications
Portable Displays Mobile Phone / Smart Phone LED Backlights Display Bias PDA, DVD, Camcorder Backlights Pager and Cordless Phone Displays Portable Medical Diagnostic Equipment Remote Controls MP3 or PMP or DSC Players Serial Flash LED Drivers
Application Diagram
VIN CIN 10F 1V 2 L1 6.8H SW 6 NC 5 CF R1 180pF D1 VOUT COUT 4.7F
IN
GND
P1
ON OFF
3
SHDN
FB
4 R2
Figure 1. Typical Application Diagram
(c) 2004 Fairchild Semiconductor Corporation FAN5336 Rev. 1.0.1 www.fairchildsemi.com
FAN5336 -- 1.5MHz Boost Regulator with 33V Integrated FET Switch
Ordering Information
Part Number
FAN5336MPX FAN5336UMPX
Package
6-Lead 3x3mm MLP 6-Lead 3x3mm UMLP
Temperature Range
-40C to +85C -40C to +85C
Pb-Free
Yes Yes
Packing Method
Tape and Reel Tape and Reel
Pin Assignments
VIN GND SHDN
1 2 3 6
SW NC FB
P1
5 4
Figure 2. 6-Lead, 3x3mm MLP (Top View)
Pin Descriptions
Pin #
P1 1 2 3 4 5 6
Name
GND VIN GND SHDN FB NC SW
Description
Analog and Power Ground. P1 must be soldered to the PCB ground. Input Voltage Pin. Ground. Shutdown Control Pin. Logic HIGH enables, logic LOW disables the device. Feedback Pin. Feedback node that connects to an external voltage divider. No Connect. Switching Node.
(c) 2004 Fairchild Semiconductor Corporation FAN5336 Rev. 1.0.1
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FAN5336 -- 1.5MHz Boost Regulator with 33V Integrated FET Switch
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only.
Symbols
VIN VIN to GND FB, SHDN to GND SW to GND TL TJ TSTG JA ESD
Parameter
Min.
-0.3 -0.3
Max.
6.0 VIN + 0.3 35 300 150
Unit
V V V C C C C/W kV
Lead Soldering Temperature (10 seconds) Junction Temperature Storage Temperature Thermal Resistance Electrostatic Discharge Protection Level(1) HBM CDM 2 1 -55
150 265
Note: 1. Using EIA/JESD22A114B (Human Body Model) and EIA/JESD22C101-A (Charge Device Model).
Recommended Operating Conditions
The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to absolute maximum ratings.
Symbols
VIN VOUT TA COUT Input Voltage Output Voltage
Parameter
Min.
2.7 9 -40 2.2(2)
Typ.
Max.
5.5 33
Unit
V V C F
Ambient Operating Temperature Output Capacitance
25
85 10
Note: 2. This load capacitance value is required for loop stability. Tolerance, temperature variation, and voltage dependency of the capacitance must be considered. Typically a 4.7F ceramic capacitor is required to achieve the specified value at VOUT = 33V.
(c) 2004 Fairchild Semiconductor Corporation FAN5336 Rev. 1.0.1
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FAN5336 -- 1.5MHz Boost Regulator with 33V Integrated FET Switch
Electrical Characteristics
VIN = 2.7 to 5.5V, VSHDN = VIN, and TA = -40C to +85C. Typical values are at TA = 25C and VIN = 3.6V unless otherwise noted.
Parameter
Output Voltage Accuracy Switch Current Limit Load Current Switch On-Resistance Quiescent Current OFF Mode Current Shutdown Threshold Shutdown Pin Bias Current Feedback Voltage (VREF) Feedback Pin Bias Current Feedback Voltage Line Regulation(3) Switching Frequency Maximum Duty Cycle Start-up Turn-on Time Load Regulation Switch Leakage Current VIN = 3.6V VIN = 3.2V
Conditions
Refer to the Test Circuit in Figure 3.
Min.
-3 1.1 75 100
Typ.
Max.
+3
Units
% A mA
1.5
1.8
VOUT = 21V 5%, VIN 3.0V VOUT = 21V 5%, VIN 3.2V, TON < 0.4s, TOFF > 3.6s VIN = 3.6V No Switching, VFB 1.27V Switching VSHDN = 0V Device ON Device OFF VSHDN = 0V or VSHDN = 5.5V ILoad = 0mA, VIN = 3.6V at 25C
0.4 0.7 6.5 0.1 1.5 0.5 1 1.205 1.230 1 10 1.255 10 1.5 1.85 5.0 1 3.0
mA A V nA V nA %/V MHz % ms % A
3.0V < VIN < 5.5V, ILOAD = 0mA 1.15 87 VIN = 3.0V, IOUT = 75mA VIN = 3.6V, 1mA < ILoad <100mA No Switching, VIN = 5.5V
0.4 1.50 93 3.0 0.2
Note: V OUT 1 3.The line regulation is calculated based on ------------------ x -------------- . V IN V OUT
Test Circuit
VIN CIN 10F 1V 2 2.7V to 5.5V L 6.8H SW 6 NC 5 FB 4 R2 10k CF R1 160k 180pF BAT54 VOUT COUT 4.7F
IN
GND
P1
ON OFF
3
SHDN
Figure 3. Test Circuit
(c) 2004 Fairchild Semiconductor Corporation FAN5336 Rev. 1.0.1
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FAN5336 -- 1.5MHz Boost Regulator with 33V Integrated FET Switch
Typical Performance Characteristics
VIN=3.6V, VOUT=21V, TA=25C, CIN=10F, COUT=4.7F, L=6.8H, CF=180pF, R1=160k, R2=10k unless otherwise noted.
Efficiency vs. Load Current
90 85 80 75 70 65 60 55 50 45 40 10 20 30 40 50 60 70 80
Load Regulation
21.5 21.3 21.1 20.9 Vin=2.7V 20.7 20.5 10 20 30 40 50 60 70 80 90 100 Vin=3.6V Vin=5.5V
Vin=2.7V Vin=3.6V Vin=5.5V
90
100
Load Current (mA)
Output Voltage (V)
Efficiency (%)
Load Current (mA)
Figure 4. Efficiency vs. Load Current
Figure 5. Load Regulation
Line Regulation at No Load
22 21.8 21.6 21.4 21.2 21 20.8 20.6 20.4 20.2 20 2.5 3 3.5 4 4.5 5 5.5
Output Voltage(V)
Battery Voltage(V)
Figure 6. Line Regulation at No Load
Figure 7. 100mA Load Current Operation
Figure 8. Start-up Response
Figure 9. Load Transient Response
(c) 2004 Fairchild Semiconductor Corporation FAN5336 Rev. 1.0.1
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FAN5336 -- 1.5MHz Boost Regulator with 33V Integrated FET Switch
Block Diagram
SHDN 3 Shutdown Circuitry VIN 1 SW 6
FB
+ Comp -
1.15 x VREF Thermal Shutdown FB 4 Error Amp + + Comp -
R R R S Q Driver n
Ramp Generator Oscillator
Current Limit Comparator
-
+
+ Amp Reference Soft-Start 5 NC
0.03
2 GND
Figure 10. Block Diagram
Circuit Description
The FAN5336 is a pulse-width modulated (PWM) current-mode boost converter. The FAN5336 improves the performance of battery-powered equipment by significantly minimizing the spectral distribution of noise at the input caused by the switching action of the regulator. To facilitate effective noise filtering, the switching frequency was chosen to be high, 1.5MHz. An internal soft-start circuit minimizes in-rush currents. The timing of the soft-start circuit was chosen to reach 95% of the nominal output voltage within 5ms following an enable command when VIN = 2.7V, VOUT = 21V, ILOAD = 35mA and COUT (EFFECTIVE) = 4.7F. The device architecture is a current-mode controller with an internal sense resistor connected in series with the Nchannel switch. The voltage at the feedback pin tracks the output voltage at the cathode of the external Schottky diode (shown in the test circuit in Figure 3). The error amplifier amplifies the difference between the feedback voltage and the internal bandgap reference. The amplified error voltage serves as a reference voltage to the PWM comparator. The inverting input of the PWM comparator consists of the sum of two components: the amplified control signal received from the 30m current sense resistor and the ramp generator voltage derived from the oscillator. The oscillator sets the latch and the latch turns on the FET switch. Under normal operating conditions, the PWM comparator resets the latch and turns off the FET, terminating the pulse. Since the comparator input contains information about the output voltage and the control loop is arranged to form a negative feedback loop, the value of the peak inductor current is adjusted to maintain regulation. Every time the latch is reset, the FET is turned off and the current flow through the switch is terminated. The latch can be reset by other events as well, such as overcurrent and over-voltage conditions. Over-current condition is monitored by the current-limit comparator, which resets the latch and turns off the switch within each clock cycle. An over-voltage condition at the feedback (FB) pin is detected by a fast comparator limiting the duty cycle in a similar manner to over-current monitoring.
(c) 2004 Fairchild Semiconductor Corporation FAN5336 Rev. 1.0.1
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FAN5336 -- 1.5MHz Boost Regulator with 33V Integrated FET Switch
Applications Information
Setting the Output Voltage
The internal feedback voltage reference (VREF) is 1.23V (typical). The output voltage is divided by a resistor divider, R1 and R2 to the FB pin. The output voltage is calculated by: V OUT R 1 = V REF 1 + ------ R 2 EQ 1 Table 3: Recommended Capacitors Cap. Value Vendor Part Number 10F 4.7F Murata Murata GRM31CR70J106KA01B GRM32RR61E475KC31B
A feedforward capacitor (CF ) is required for stability. The recommended value is around 180pF.
Diode Selection
The external diode used for rectification is usually a Schottky diode. Its average forward current should exceed the load current and its reverse voltage maximum ratings should exceed the voltage at the output of the converter. A barrier Schottky diode, such as BAT54, is preferred due to its low reverse current over the temperature range. Care should be taken to avoid any short circuit of VOUT to GND, even with the IC disabled, since the diode can be instantly damaged by the excessive current.
The maximum output current depends on the output voltage settings. Table 1 provides the recommended voltage for several steady-state configurations: Table 1: Recommended Voltages ILOAD Max. R1 (k) for VOUT (V) (mA) R2 = 10k 9 9 12 21 33 33 50 170 125 75 50 10 63.2 63.2 87.5 160 258 258 VIN Range (V) 2.7 to 5.5 2.9 to 4.7 2.7 to 5.5 3.6 to 5.5 4.0 to 5.5 2.7 to 5.5
Flash LED Driver
The FAN5336 may be used to drive a serial flash LED with up to 100mA current at 21V for a maximum of 400ms on-time and 10% duty cycle.
Inductor Selection
The inductor parameters directly related to device performance are saturation current and DC resistance. The FAN5336 operates with a typical inductor value of 6.8H. The lower the DC resistance, the higher the efficiency. Balancing inductor size, cost, and overall efficiency allows optimum choice. The inductor saturation current should be rated around 1.5A, which is the threshold of the internal current limit circuit. This limit is reached only during the start-up and with heavy load conditions. When this occurs, the converter can shift into discontinuous conduction mode due to the automatic turn-off of the switching transistor, resulting in higher ripple and reduced efficiency. Table 2: Recommended Inductors Inductor Value Vendor Part Number 6.8H 6.8H TDK SLF7028T6R8M1R3
Thermal Shutdown
When the die temperature exceeds 150C, a reset occurs and remains in effect until the die cools to 130C, when the circuit is allowed to restart.
PCB Layout Recommendations
The inherently high peak currents and switching frequency of power supplies require careful PCB layout design. For best results, use wide traces for high-current paths and place the input capacitor, the inductor, and the output capacitor as close as possible to the integrated circuit terminals. The resistor divider that sets the output voltage should be routed away from the inductor to avoid RF coupling. A four-layer PCB, with at least one ground plane connected to Pin 2 of the IC, is recommended. The ground plane acts as an electromagnetic shield to reduce EMI and parasitic coupling between components.
Comment Lower Profile Higher Efficiency
Murata LQS66C6R8M04
Capacitors Selection
For best performance, low-ESR input and output capacitors are required. Ceramic capacitors of CIN = 10F and COUT = 4.7F, placed as close as possible to the IC pins, are recommended for the lower input and output ripple. The output capacitor voltage rating should be selected according to the VOUT setting.
(c) 2004 Fairchild Semiconductor Corporation FAN5336 Rev. 1.0.1
Figure 11. Recommended PCB Layout
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FAN5336 -- 1.5MHz Boost Regulator with 33V Integrated FET Switch
Mechanical Dimensions
Dimensions are in millimeters unless otherwise noted.
Figure 12. 6-Lead 3x3 Molded Leadless Package (MLP)
(c) 2004 Fairchild Semiconductor Corporation FAN5336 Rev. 1.0.1
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FAN5336 -- 1.5MHz Boost Regulator with 33V Integrated FET Switch
Mechanical Dimensions
Dimensions are in millimeters unless otherwise noted.
2.45 0.15 C 3.0 A B
6
4
2X
1.65 3.0 (0.70)
2.10 3.50
1
0.15 C 0.95 TYP
3
0.65 TYP
2X
0.6 MAX 0.10 C (0.20)
0.08 C
0.05 0.00
C
SEATING PLANE
2.00 PIN #1 IDENT
1
0.45 0.20
3
1.21
0.2 MIN 0.95
6
1.90
4
0.30~0.45 0.10 CAB C 0.05
A. CONFORMS TO JEDEC REGISTRATION MO-229, VARIATION VEEA, DATED 8/2003, EXCEPT THICKNESS B. DIMENSIONS ARE IN MILLIMETERS. C. DIMENSIONS AND TOLERANCES PER ASME Y14.5M, 1994 D. FILENAME AND REVISION: UMLP06Arev1
Figure 12. 6-Lead 3x3 Ultrathin Molded Leadless Package (UMLP)
(c) 2004 Fairchild Semiconductor Corporation FAN5336 Rev. 1.0.1
www.fairchildsemi.com 9
FAN5336 -- 1.5MHz Boost Regulator with 33V Integrated FET Switch
(c) 2004 Fairchild Semiconductor Corporation FAN5336 Rev. 1.0.1
www.fairchildsemi.com 10

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