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19-2426; Rev 0; 4/02
Regulated 5V USB Charge Pump with Programmable Current Limit
General Description
The MAX5008 charge-pump regulator generates a regulated 5V output up to 125mA with a 2.95V to 5.5V input voltage range. The device includes resistor-programmable overcurrent limit. The MAX5008 requires a minimum number of external components for normal operation. The high 1MHz switching frequency allows the use of small surface-mount ceramic capacitors. The fault-protection circuitry limits the output current when it exceeds the limit set by an external resistor. The output current can range from 1mA to 150mA to accommodate circuit requirements. A FAULT output indicates when the device is in current limit or the output is out of regulation. A low-power shutdown mode reduces supply current to less than 1A and places the output in a high-impedance state. The MAX5008 is offered in a space-saving 10-pin MAX package that is only 1.1mm high. o Regulated 5V Output Up to 125mA o Indefinite Short-Circuit Protection o Adjustable Output Current Limit o No Inductors Required o 0.1A Shutdown Current o Thermal Shutdown o Fault Output Indicates Overcurrent or Output Voltage Out of Regulation o 2.95V to 5.5V Input Voltage Range o 10-Pin MAX Package
Features
MAX5008
Applications
Flash Memory Supplies USB Host Devices Battery-Powered Systems 3.3V to 5V Local Conversion
PART MAX5008CUB
Ordering Information
TEMP RANGE 0C to +70C PIN-PACKAGE 10 MAX
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
CX 0.68F 7 VIN 2.95V TO 5.5V 4.7F CXN 8 IN 2 OUT MAX5008 3 FAULT RCS 1 200* CEXT GND 4 PGND 6 10 IOUT CEXT 6.8F 47nF* RCS 0.4 200* VOUT 5V COUT 4.7F 9 CXP
5
SHDN
100k
*USE IF PRECISION CURRENT LIMIT IS REQUIRED.
________________________________________________________________ Maxim Integrated Products
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Regulated 5V USB Charge Pump with Programmable Current Limit MAX5008
ABSOLUTE MAXIMUM RATINGS
IN, SHDN, RCS, FAULT, OUT to GND .....................-0.3V to +6V PGND to GND.....................................................................0.3V CXN to GND ................................................-0.3V to (VIN + 0.3V) CXP to GND ............................................-0.3V to (VCEXT + 0.3V) CEXT to GND ..........................................-0.3V to (VCEXT + 0.3V) Short-Circuit Duration to GND .......................................Indefinite Continuous Power Dissipation (TA = +70C) 10-Pin MAX.................................................................444mW Operating Temperature Range...............................0C to +70C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and 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 affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN = SHDN = 3V, CIN = 4.7F, CX = 0.68F, CEXT = 6.8F, COUT = 4.7F, RCS = 0.4, TA = 0C to +70C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER Input Voltage Range (Note 1) Input Undervoltage Lockout Threshold Input Undervoltage Lockout Hysteresis Output Voltage (Note 2) Output Voltage Ripple VOUT Fault Threshold Maximum Output Current No-Load Input Current SHDN Logic High SHDN Logic Low Shutdown Supply Current Current-Sense Trip Level FAULT Leakage Current FAULT Logic Low FAULT Assertion Delay (Note 4) FAULT Deassertion Delay (Note 5) Switching Frequency Startup Time tSTART VOUT > VTH, RLOAD = 46, from rising edge of SHDN tFD tFDD VOUT VRIP VTH IOUT IQ VINH,SHDN VINL,SHDN IQSHDN VCS SHDN = low VCS = IOUT x RCS (Note 3) VFAULT = 5V, OUT in regulation IOUT > ILIMIT, or VOUT < VTH, IFAULT = 1mA IOUT > ILIMIT VOUT < VTH IOUT < ILIMIT and VOUT > 4.5V 0.5 2 30 16 1 200 1.5 55 0.1 60 VOUT = 5V 4% IOUT = 0, VIN = 4.25V IOUT = 0, VIN = 3.3V 2.4 0.4 10 73 1 0.4 SYMBOL VIN IOUT = 125mA IOUT = 70mA Rising edge Falling edge 0 IOUT < 30mA, 2.95V < VIN < 5.5V 0mA IOUT 100mA, 2.95V VIN 4.25V 0mA IOUT 125mA 4.22 100 140 0.6 1 6 6 4.75 4.75 CONDITIONS MIN 2.95 2.95 2.0 2.35 100 5.0 5.0 100 4.50 5.30 5.25 TYP MAX 4.25 5.50 2.6 UNITS V V mV V mV V mA mA V V A mV A V ms s ms MHz s
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Regulated 5V USB Charge Pump with Programmable Current Limit
ELECTRICAL CHARACTERISTICS (continued)
(VIN = SHDN = 3V, CIN = 4.7F, CX = 0.68F, CEXT = 6.8F, COUT = 4.7F, RCS = 0.4, TA = 0C to +70C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER Thermal Shutdown Junction Temperature Thermal Shutdown Hysteresis SYMBOL CONDITIONS MIN TYP 150 30 MAX UNITS C C
MAX5008
Note 1: Note 2: Note 3: Note 4:
When the input exceeds 4.25V, the power dissipation on the chip exceeds the maximum rating if the output current is 125mA. The MIN/MAX limits are 100% production tested at +25C and +70C, and guaranteed by design at 0C. IOUT is output current flowing from CEXT. The delay from the fault event to the assertion of FAULT. Fault delays are specified with either a current fault or a voltage fault, but not both simultaneously. Note 5: The delay from the removal of the fault event to the deassertion of FAULT.
Typical Operating Characteristics
(VIN = 3V, CIN = 4.7F, CX = 0.47F, COUT = 4.7F, CEXT = 4.7F, RCS = 0.4, TA = +25C, unless otherwise noted.)
NO-LOAD SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX5008 toc01
OUTPUT VOLTAGE vs. LOAD CURRENT
MAX5008 toc02
OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
ILOAD = 100mA
MAX5008 toc03
2.0
5.5
6 5 OUTPUT VOLTAGE (V) 4 3 2 1 0
SUPPLY CURRENT (mA)
1.5 OUTPUT VOLTAGE (V)
5.3 VIN = 5.0V
5.1
1.0
4.9 VIN = 2.9V 4.7 VIN = 3.3V
0.5
0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V)
4.5 1 10 100 1000 LOAD CURRENT (mA)
0
1
2
3
4
5
6
SUPPLY VOLTAGE (V)
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Regulated 5V USB Charge Pump with Programmable Current Limit MAX5008
Typical Operating Characteristics (continued)
(VIN = 3V, CIN = 4.7F, CX = 0.47F, COUT = 4.7F, CEXT = 4.7F, RCS = 0.4, TA = +25C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 1 10 100 1000 200ns/div 1ms/div LOAD CURRENT (mA) VIN = 3.3V 10mV/div 0 5V 0 SHDN VIN = 2.95V
MAX5008 toc04
OUTPUT WAVEFORM
MAX5008 toc05
SHUTDOWN TIMING
MAX5008 toc06
100
RL = 46 5V VOUT
LINE-TRANSIENT RESPONSE
MAX5008 toc07
LOAD-TRANSIENT RESPONSE
MAX5008 toc08
ILOAD = 100mA A
3.6V 3.1V
100mA A 10mA
B
B
40s/div A: INPUT VOLTAGE: 500mV/div B: OUTPUT VOLTAGE: AC-COUPLED, 100mV/div
40s/div A: LOAD CURRENT B: OUTPUT VOLTAGE: AC-COUPLED, 100mV/div
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Regulated 5V USB Charge Pump with Programmable Current Limit
Pin Description
PIN 1 2 3 4 5 6 7 8 9 10 NAME RCS OUT FAULT GND SHDN PGND CXN IN CXP CEXT FUNCTION External Current-Sense Resistor. Connect a resistor from RCS to OUT to set the overcurrent threshold. ILIMIT = 60mV / RCS. Fixed 5V Output. Bypass OUT to GND with a 4.7F capacitor. Output Fault Indicator. FAULT is asserted when either IOUT > ILIMIT or VOUT < VTH. FAULT is an open-drain output that is high during normal operation or during shutdown. Ground Pin. Connect GND to PGND. Shutdown Input. When SHDN = low, the device turns off. Drive SHDN high or connect to IN for normal operation. Power Ground Pin. Connect PGND to GND. Negative Terminal of the Charge-Pump Capacitor. Connect a 0.68F capacitor from CXN to CXP. Input Supply, 2.95V to 5.5V. Bypass IN to GND with a 4.7F ceramic capacitor. Positive Terminal of the Charge-Pump Capacitor. Connect a 0.68F capacitor from CXP to CXN. Charge-Pump Output. Bypass CEXT to PGND with a 6.8F capacitor.
MAX5008
Detailed Description
The MAX5008 charge pump provides a regulated 5V output from a 2.95V to 5.5V input. The device delivers a maximum of 125mA load current. Designed specifically for compact applications, a complete regulator circuit requires a minimum number of external components.
Shutdown Mode
Driving SHDN low places the device in shutdown mode, which disables the oscillator, the control logic, and the reference. The output goes into high-impedance state and drops to ground if loaded. Placing the device in shutdown mode reduces the supply current to less than 0.1A. In normal operation, SHDN is driven high or connected to IN.
Adjustable Current Limit
The MAX5008 has an adjustable overcurrent protection. An external current-sense resistor is connected from RCS to OUT to set the current limit. The current limit is defined by: ILIMIT = VCS / RCS where VCS is the current-sense trip level, typically 60mV. For example, ILIMIT = 150mA when RCS = 0.40. When the output current limit is exceeded, the output voltage falls and the device maintains the average output current at ILIMIT. Upon removal of the overcurrent condition, the part resumes normal operation.
Applications Information
Capacitor Selection
The MAX5008 requires four external capacitors. Their values depend on the required output current. Table 1 shows the capacitor values recommended for different load currents.
Input Voltage Range
The MAX5008 maintains a regulated 5V output with input voltages from 2.95V to 5.5V. If the input voltage exceeds 4.25V, limit the output current to 75mA or less. This keeps the MAX5008 within its maximum power dissipation limits.
FAULT Indication
When IOUT > ILIMIT or VOUT < VTH, FAULT asserts. FAULT is an open-drain output that needs to be connected through a 100k (typ) pullup resistor to a logic supply voltage.
Table 1. Recommended Capacitor Values
IOUT 50mA 125 mA CIN (F) 3.3 4.7 CX (F) 0.33 0.68 CEXT (F) 3.3 6.8 COUT (F) 3.3 4.7
Thermal Shutdown
The MAX5008 has internal thermal shutdown circuitry, which shuts down the device when the die temperature exceeds +150C. The thermal shutdown circuitry has 30C hysteresis.
Layout Considerations
All capacitors should be located as close to the IC as practical. Connect GND and PGND through a short,
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Regulated 5V USB Charge Pump with Programmable Current Limit MAX5008
Functional Diagram
TOP VIEW
IN CEXT RCS
Pin Configuration
RCS 1 OUT 2 3 4 5
10 CEXT 9 CXP IN CXN PGND
CXN SWITCHES CXP CONTROL
OUT
FAULT GND SHDN
MAX5008
8 7 6
MAX
MAX5008
PGND
FAULT SHDN
GND
low-impedance trace, and connect the ground for CIN, CEXT, and COUT directly to PGND in a star configuration. Connect RCS to CEXT through a short and low impedance trace.
Chip Information
TRANSISTOR COUNT: 2632 PROCESS: BiCMOS
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Regulated 5V USB Charge Pump with Programmable Current Limit
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
10LUMAX.EPS
MAX5008
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 7 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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