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FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
March 2007
FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
Features
Low-Noise, Constant-Frequency Operation at Heavy
Description
The FAN5602 is a universal switched capacitor DC/DC converter capable of step-up or step-down operation. Due to its unique adaptive fractional switching topology, the device achieves high efficiency over a wider input/ output voltage range than any of its predecessors. The FAN5602 utilizes resistance-modulated loop control, which produces lower switching noise than other topologies. Depending upon actual load conditions, the device automatically switches between constant-frequency and pulse-skipping modes of operation to extend battery life. The FAN5602 produces a fixed regulated output within the range of 2.7V to 5.5V from any type of voltage source. High efficiency is achieved under various input/ output voltage conditions because an internal logic circuit automatically reconfigures the system to the best possible topology. Only two 1F bucket capacitors and one 10F output capacitor are needed. During power on, soft-start circuitry prevents excessive current drawn from the supply. The device is protected against short-circuit and over-temperature conditions. The FAN5602 is available with 3.3V, 4.5V, and 5.0V output voltage. Any other output voltage option within the 1.5V to 5V range is available upon request. The FAN5602 is available 3x3mm 8-lead MLP packages.
Load High-Efficiency, Pulse-Skip (PFM) Operation at Light Load Switch Configurations (1:3, 1:2, 2:3, 1:1, 3:2, 2:1, 3:1) 92% Peak Efficiency Input Voltage Range: 2.7V to 5.5V Output Current: 3.3V, 200mA at VIN = 3.6V 3% Output Voltage Accuracy ICC < 1A in Shutdown Mode 1MHz Operating Frequency Shutdown Isolates Output from Input Soft-Start Limits Inrush Current at Start-up Short-Circuit and Over-Temperature Protection Minimum External Component Count No Inductors
Applications
Cell Phones Handheld Computers Portable RF Communication Equipment Core Supply to Low-Power Processors Low-Voltage DC Bus DSP Supplies
Ordering Information
Part Number
FAN5602MP33X FAN5602MP45X
Package(1)
3x3mm 8-Lead MLP 3x3mm 8-Lead MLP
Pb-Free
Yes Yes Yes
Output Voltage, VNOM
3.3V 4.5V 5.0V
FAN5602MP5X 3x3mm 8-Lead MLP Note: 1. Reference MLP08D Option B ONLY.
Application Diagram
Input 2.7V to 5.5V VIN ENABLE
1
CIN CB
C2C2+
2 3 4
FAN5602
8 6 7 5
C1+
VOUT
COUT
GND
C1-
Figure 2. Typical Application Diagram
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 www.fairchildsemi.com
FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
Block Diagram
ENABLE VIN C1C1+
BAND GAP VOUT
FB SOFT-START BG
ERROR AMP
EN
Heavy Load
CURRENT SENSE Light load FB PFM BG EN
S W I T C H A R R A Y
C2+
REF
CONTROL LOGIC
VIN
MODE
DRIVER
C2-
150mV VOUT SC
1.6V VIN UVLO OSCILLATOR VIN VOUT GND
Figure 3. Block Diagram
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 2
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FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
Pin Assignments
VIN C2+ C2GND
1 2 3 4
8 7 6 5
ENABLE C1+ VOUT C1-
3x3mm 8-Lead MLP
Figure 4. Pin Assignments
Pin Descriptions
Pin #
1 2 3 4 5 6 7 8
Name
VIN C2+ C2GND C1VOUT C1+ ENABLE Supply Voltage Input.
Description
Bucket Capacitor2. Positive Connection. Bucket Capacitor2. Negative Connection. Ground Bucket Capacitor1. Negative Connection. Regulated Output Voltage. Bypass this pin with 10F ceramic low-ESR capacitor. Bucket Capacitor1. Positive Connection. Enable Input. Logic high enables the chip and logic low disables the chip, reducing the supply current to less than 1A. Do not float this pin.
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 3
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FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
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.
Symbol
VIN PD TL TJ TSTG ESD
Parameter
VIN, VOUT, ENABLE,Voltage to GND Voltage at C1+,C1-,C2+, and C2-to GND Power Dissipation Lead Soldering Temperature (10 seconds) Junction Temperature Storage Temperature Human Body Model (HBM) Charged Device Model (CDM)
Min.
-3.0 -3.0
Max.
6.0 VIN +0.3 Internally Limited 300 150
Unit
V V C C C kV kV
-55
150 2 2
Note: 2. Using Mil Std. 883E, method 3015.7 (Human Body Model) and EIAJ/JESD22C101-A (Charged 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.
Symbol
VIN IL
Parameter
Input Voltage VIN < 2V Load Current
Condition
Min.
1.8
Typ.
Max.
5.5 30 200 100
Unit
V mA C
3.3V, VIN = 3.6V 4.5& 5.5,VIN = 3.6V -40
Ambient Temperature TA Note: 3. Refer to Figure 9 in Typical Performance Characteristics.
+85
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 4
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FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
DC Electrical Characteristics
VIN = 2.7V to 5.5V, C1 = C2 = 1F, CIN = COUT = 10F, ENABLE = VIN, TA = -40C to +85C unless otherwise noted. Typical values are at TA = 25C.
Symbol
VUVLO VOUT IQ
Parameter
Input Under-Voltage Lockout Output Voltage Quiescent Current Off Mode Supply Current Output Short-Circuit
Condition
Min.
1.5
Typ.
1.7 VNOM 170 0.1
Max.
2.2 1.03 x VNOM 300 1.0 200
Unit
v V A A mA
VIN 0.75 x VNOM, 0mA < ILOAD <100mA VIN 1.1 x VNOM, ILOAD = 0mA ENABLE = GND VOUT < 150mV VIN = 0.85 x VNOM, ILOAD = 30mA 3.3V 4.5,5.0V 3.3V 4.5,5.0V
0.97 x VNOM
75 80 90 92 0.7 1.0 145 15 1.5 0.5 -1 0.5 10 1 1.3 MHz C C V V A ms mVpp %
Efficiency
VIN = 1.1 x VNOM, ILOAD = 30mA TA = 25C
fOSC TSD TSDHYS VIH VIL IEN tON
Oscillator Frequency Thermal Shutdown Threshold Thermal Shutdown Threshold Hysteresis ENABLE Logic Input High Voltage ENABLE Logic Input Low Voltage
ENABLE Logic Input Bias ENABLE =VIN or GND Current VOUT Turn-On Time VOUT Ripple VIN = 0.9 x VNOM, ILOAD = 0mA,10% to 90% VIN = 2.5V, ILOAD = 200mA
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 5
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FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
Typical Performance Characteristics
TA = 25C, VOUT = 4.5V unless otherwise noted.
180 160
80 70
Shutdown Current (nA)
140
Quiescent Current (A)
60 50 40 30 20 10 0
120 100 80 60 40 20 0 1.5 2.5 3.5 4.5 5.5
1
2
3
4
5
6
Input Voltage (V)
Input Voltage (V)
Figure 4. Quiescent Current vs. Input Voltage
4.55
Figure 5. Shutdown Current vs. Input Voltage
100 90
4.50
Output Voltage (V)
4.45
ILOAD = 100mA VOUT = 4.5V
80
Efficiency
70 60 50 40 30
Load Current = 10mA Load Current = 50mA Load Current = 100mA Load Current = 150mA
4.40
4.35
4.30 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
20 2.500
3.000
3.500
4.000
4.500
5.000
5.500
Input Voltage (V)
Input Voltage
Figure 6. Line Regulation
4.6 4.5
Figure 7. Efficiency vs. Input Voltage
700.0 600.0
Output Voltage (V)
VIN = 3.6V
Load Current (mA)
4.4 4.3 4.2 4.1 4.0 1 50 100 150 200 250 300 350
500.0 400.0 300.0 200.0 100.0 0.0 2 2.5 3
DVOUT < 10% DVOUT < 3%
3.5
4
4.5
5
Load Currrent (mA)
Input Voltage (V)
Figure 8. Load Regulation
Figure 9. Output Current Capacity vs. Input Voltage
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 6
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FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
Typical Performance Characteristics (Continued)
TA = 25C and VOUT = 4.5V unless otherwise noted.
5 4.5
4.5 Load Current = 10mA 4.45
Output Voltage (V)
4 3.5 3 2.5 2 2 3 4 5 6
Load Current = 10mA Load Current = 50mA Load Current = 100mA Load Current = 150mA Load Current = 200mA
Output Voltage (V)
4.4
4.35
4.3 -60 -40 -20 0 20 40 60 80 100 120 140
Input Voltage (V)
Ambient Temperature (C)
Figure 10. Output Voltage vs. Input Voltage
Figure 11. Output Voltage vs. Ambient Temperature
80
1.4 1.3
75
Efficiency (%)
70
Enable (V)
250 300
VIN = 3.6V
1.2 1.1 1 0.9
65
60 0 50 100 150 200
0.8 2 2.5 3 3.5 4 4.5 5 5.5 6
Figure 12. Peak Efficiency vs. Load Current
Figure 13. Enable Threshold vs. Input Voltage
5.5
Mode 1
Mode Change Threshold (V)
5 4.5 4 3.5 3 2.5 2 0 50 100 150 200
Mode 4 Mode 3 Mode 2
Load Current (mA)
Figure 14. Mode Change Threshold and Hysteresis
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 7
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FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
Typical Performance Characteristics (Continued)
TA = 25C, VOUT = 3.3V unless otherwise noted.
Outp ut Volt age
VIN = 3.7V C OUT = 5F TA = 25 C
o
Lo ad Curr ent
(100mA /div )
(50mV/div)
Time (10s/div)
Figure 15. Load Transient Response (LDO Mode)
Outp ut Voltag e
V IN = 3.0 V
(50mV/div)
C OU T = 5F TA = 25 oC
Loa d Cur rent
(100mA/di v)
Time (10s/div)
Figure 16. Load Transient Response (2:3 Mode)
Output Voltage
(50mV/di v)
VIN = 2.5 V TA = 25oC , COUT = 5F
Load Current
(100mA /div )
Figure 17. Load Transient Response (1:2 Mode)
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 8 www.fairchildsemi.com
FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
Typical Performance Characteristics (Continued)
TA = 25C, CIN = COUT = 10F, CB = 1F, VOUT = 4.5V unless otherwise noted.
IOUT = 200mA VIN = 2.5V Output Ripple (20 mV/div)
IOUT = 200mA VIN = 3.6V Output Ripple (20 mV/div)
Time (100 s/div)
Time (100 s/div)
Figure 18. Output Ripple
Figure 19. Output Ripple
IOUT = 200mA VIN = 4.2V Output Ripple (20 mV/div)
IOUT = 300mA VIN = 2.5V Output Ripple (20 mV/div)
Time (100 s/div)
Time (100 s/div)
Figure 20. Output Ripple
Figure 21. Output Ripple
IOUT= 300mA VIN = 3.6V Output Ripple (20 mV/div)
IOUT = 300mA VIN = 4.2V Output Ripple (20 mV/div)
Time (100 s/div)
Time (100 s/div)
Figure 22. Output Ripple
Figure 23. Output Ripple
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 9
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FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
Functional Description
FAN5602 is a high-efficiency and low-noise switched capacitor DC/DC converter capable of step-up and stepdown operations. It has seven built-in switch configurations. Based on the ratio of the input voltage to the output voltage, the FAN5602 automatically reconfigures the switch to achieve the highest efficiency. The regulation of the output is achieved by a linear regulation loop, which modulates the on-resistance of the power transistors so that the amount of charge transferred from the input to the flying capacitor at each clock cycle is controlled and is equal to the charge needed by the load. The current spike is reduced to minimum. At light load, the FAN5602 automatically switches to Pulse Frequency Modulation (PFM) mode to save power. The regulation at PFM mode is achieved by skipping pulses. input is connected to the bottom the capacitors so that the top of the capacitors is boosted to a voltage that equals VIN/2 + VIN, i.e., 3/2 x VIN. By connecting the top of the capacitors to the output, one can ideally charge the output to 3/2 x VIN. If 3/2 x VIN is higher than the needed VOUT, the linear regulation loop adjusts the onresistance to drop some voltage. Boosting the voltage of the top of the capacitors to 3/2 x VIN by connecting VIN the bottom of the capacitors, boosts the power efficiency 3/2 times. In 2:3 mode, the ideal power efficiency is VOUT/1.5 x VIN. For example, if VIN = 2V, VOUT = 2 x VIN = 4V, the ideal power efficiency is 100%. When 2 x VIN > VOUT > 1.5 x VIN, the 1:2 mode (step-up) shown in Figure 33 is used. Both in the charging phase and in pumping phase, two flying capacitors are placed in parallel. In charging phase, the capacitors are charged to the input voltage. In the pumping phase, the input voltage is placed to the bottom of the capacitors. The top of the capacitors is boosted to 2 x VIN. By connecting the top of the capacitors to the output, one can ideally charge the output to 2 x VIN. Boosting the voltage on the top of the capacitors to 2VIN boosts the power efficiency 2 times. In 1:2 mode, the ideal power efficiency is VOUT/2 x VIN. For example, VIN = 2V, VOUT = 2 x VIN = 4V, the ideal power efficiency is 100%. When 3 x VIN > VOUT > 2 x VIN, the 1:3 mode (step-up) shown in Figure 34 is used. In charging phase, two flying capacitors are placed in parallel and each is charged to VIN. In the pumping phase, the two flying capacitors are placed in series and the input is connected to the bottom of the series connected capacitors. The top of the series connected capacitors is boosted to 3 x VIN. The ideal power efficiency is boosted 3 times and is equal to VOUT/ 3VIN. For example, VIN = 1V, VOUT = 3 x VIN = 3V, the ideal power efficiency is 100%. By connecting the output to the top of the series connected capacitors, one can charge the output to 3 x VIN. The internal logic in the FAN5602 monitors the input and the output compares them, and automatically selects the switch configuration to achieve the highest efficiency. The step-down modes 3:2, 2:1, and 3:1 can be understood by reversing the function of VIN and VOUT in the above discussion. The built-in modes improve power efficiency and extend the battery life. For example, if VOUT = 5V, mode 1:2 needs a minimum VIN = 2.5V. By built-in 1:3 mode, the minimum battery voltage is extended to 1.7V.
Linear Regulation Loop
The FAN5602 operates at constant frequency at load higher than 10mA. The linear regulation loop consisting of power transistors, feedback (resistor divider), and error amplifier is used to realize the regulation of the output voltage and to reduce the current spike. The error amplifier takes feedback and reference as inputs and generates the error voltage signal. The error voltage signal is then used as the gate voltage of the power transistor and modulates the on-resistance of the power transistor and, therefore, the charge transferred from the input to the output is controlled and the regulation of the output is realized. Since the charge transfer is controlled, the FAN5602 has a small ESR spike.
Switch Array
Switch Configurations The FAN5602 has seven built-in switch configurations, including 1:1, 3:2, 2:1 and 3:1 for step-down and 2:3, 1:2 and 1:3 for step-up. When 1.5 x VOUT > VIN > VOUT, the 1:1 mode shown in Figure 31 is used. In this mode, the internal oscillator is turned off. The power transistors connecting the input and the output become pass transistors and their gate voltages are controlled by the linear regulation loop, the rest of power transistors are turned off. In this mode, the FAN5602 operates exactly like a low dropout (LDO) regulator and the ripple of the output is in the micro-volt range. When 1.5 x VIN > VOUT > VIN, the 2:3 mode (step-up) shown in Figure 32 is used. In the charging phase, two flying capacitors are placed in series and each capacitor is charged to a half of the input voltage. In pumping phase, the flying capacitors are placed in parallel. The
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 10
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FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
Switch Array Modes
TOP
C1+ S1A S2A C1 TOP S1A
C1+
S1A S2A MID GND
C1+
MID S3B S5 S4B GND C1C2
C1 C1C1-
S3A
Figure 24. Mode 1 (1:1)
TOP
Figure 25. Mode 2 (2:3 or 3:2) All Switches Set for Phase 1 and Reverse State for Phase 2
TOP
C1+
S1A S2A
S1B S2B MID
C2+
C1+
S1A S2A S2B
C2+
C1
MID
C2 S3B
C1 S3A C1S4A
C2
C1S4A S5
S3B S4B C2-
S4B
C2-
GND
Figure 26. Mode 3 (1:2 or 2:1) All Switches Set for Phase 1 and Reverse State for Phase 2
Figure 27. Mode 4 (1:3 or 3:1) All Switches Set for Phase 1 and Reverse State for Phase 2
Light-Load Operation
The power transistors used in the charge pump are very large in size. The dynamic loss from the switching the power transistors is not small and increases its proportion of the total power consumption as the load gets light. To save power, the FAN5602 switches, when the load is less than 10mA, from constant frequency to pulse-skipping mode (PFM) for modes 2:3(3:2), 1:2(2:1) and 1:3(3:1), except mode 1:1. In PFM mode, the linear loop is disabled and the error amplifier is turned off. A PFM comparator is used to setup an upper threshold and a lower threshold for the output. When the output is lower than the lower threshold, the oscillator is turned on and the charge pump starts working and keeps delivering charges from the input to the output until the output is higher than the upper threshold. The oscillator shuts off power transistors and delivers the charge to the output from the output capacitor. PFM operation is not used for Mode 1:1, even if at light load. Mode 1:1 is designed as an LDO with the oscillator off. The power transistors at LDO mode are not switching and therefore do not have the dynamic loss. Switching from linear operation to PFM mode (ILOAD<10mA) and from PFM to linear mode (ILOAD>10mA) is automatic, based on the load current, which is monitored all the time.
Short Circuit
When the output voltage is lower than 150mV, the FAN5602 enters short-circuit condition. In this condition, all power transistors are turned off. A small transistor shorting the input and the output turns on and charges the output. This transistor stays on as long as the VOUT < 150mV. Since this transistor is very small, the current from the input to the output is limited. Once the short at the output is eliminated, this transistor is large enough to charge the output higher than 150mV and the FAN5602 enters soft-start period.
Soft Start
The FAN5602 uses a constant current, charging a lowpass filter to generate a ramp. The ramp is used as reference voltage during the startup. Since the ramp starts at zero and goes up slowly, the output follows the ramp and inrush current is restricted. When the ramp is higher than bandgap voltage, the bandgap voltage supersedes ramp as reference and the soft start is over. The soft start takes about 500s.
Thermal Shutdown
The FAN5602 goes to thermal shutdown if the junction temperature is over 150C with 15C hysteresis.
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 11
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FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
Application Information
Using the FAN5602 to Drive LCD Backlighting
The FAN5602 4.5V option is ideal for driving the backlighting and flash LEDs for portable devices. One FAN5602 device can supply the roughly 150mA needed to power both the backlight and the flash LEDs. Even though drawing this much current from the FAN5602 drives the part out of the 3% output regulation, it is not a problem. The backlight and flash LEDs still produce optimal brightness at the reduced regulation. When building this circuit, use ceramic capacitors with low ESR. All capacitors should be placed as close as possible to the FAN5602 in the PCB layout.
VIN BATTERY 3.2 to 4.2V 10F
VOUT 10F
FOL216CIW
FOL625CIW
FAN5602
50 1F 1F
50
50
50
20
BACKLIGHT
FLASH
Figure 28. Circuit for Backlighting / Flash Application
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 12
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FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
Package Dimensions
Dimensions are in millimeters unless otherwise noted.
Figure 29. 8-Lead 3x3mm Molded Leadless Package (MLP), .8mm Thick
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 13
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FAN5602 -- Universal (Step-Up/Step-Down) Charge Pump Regulated DC/DC Converter
(c) 2005 Fairchild Semiconductor Corporation FAN5602 Rev. 1.5.0 14
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