19-2426; Rev 1; 7/06
Regulated 5V USB Charge Pump with
Programmable Current Limit
General Description
The MAX5008 charge-pump regulator generates a reg-
ulated 5V output up to 125mA with a 2.95V to 5.5V input
voltage range. The device includes resistor-program-
mable overcurrent limit. The MAX5008 requires a mini-
mum 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 out-
put is out of regulation.
A low-power shutdown mode reduces supply current to
less than 1µA and places the output in a high-imped-
ance state. The MAX5008 is offered in a space-saving
10-pin µMAX
®
package that is only 1.1mm high.
♦
Regulated 5V Output Up to 125mA
♦
Indefinite Short-Circuit Protection
♦
Adjustable Output Current Limit
♦
No Inductors Required
♦
0.1µA Shutdown Current
♦
Thermal Shutdown
♦
Fault Output Indicates Overcurrent or Output
Voltage Out of Regulation
♦
2.95V to 5.5V Input Voltage Range
♦
10-Pin µMAX Package
Features
MAX5008
Applications
Flash Memory Supplies
USB Host Devices
Battery-Powered Systems
3.3V to 5V Local Conversion
µMAX is a registered trademark of Maxim Integrated Products, Inc.
PART
MAX5008CUB
Ordering Information
TEMP RANGE
0°C to +70°C
PIN-PACKAGE
10 µMAX
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
C
X
0.68µF
7
V
IN
2.95V TO 5.5V
4.7µF
CXN
8
IN
2
OUT
MAX5008
3
FAULT
RCS
1
200Ω*
CEXT
GND
4
PGND
6
10
I
OUT
C
EXT
6.8µF
47nF*
R
CS
0.4Ω
200Ω*
V
OUT
5V
C
OUT
4.7µF
9
CXP
5
SHDN
100kΩ
*USE IF PRECISION CURRENT LIMIT IS REQUIRED.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
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 (V
IN
+ 0.3V)
CXP to GND ............................................-0.3V to (V
CEXT
+ 0.3V)
CEXT to GND ..........................................-0.3V to (V
CEXT
+ 0.3V)
Short-Circuit Duration to GND .......................................Indefinite
Continuous Power Dissipation (T
A
= +70°C)
10-Pin µMAX.................................................................444mW
Operating Temperature Range...............................0°C to +70°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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
(V
IN
=
SHDN
= 3V, C
IN
= 4.7µF, C
X
= 0.68µF, C
EXT
= 6.8µF, C
OUT
= 4.7µF, R
CS
= 0.4Ω, T
A
= 0°C to +70°C, unless otherwise noted.
Typical values are at T
A
= +25°C.)
PARAMETER
Input Voltage Range
(Note 1)
Input Undervoltage Lockout
Threshold
Input Undervoltage Lockout
Hysteresis
Output Voltage
(Note 2)
Output Voltage Ripple
V
OUT
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
t
START
V
OUT
> V
TH
, R
LOAD
= 46Ω, from rising edge
of
SHDN
t
FD
t
FDD
V
OUT
V
RIP
V
TH
I
OUT
I
Q
V
INH,SHDN
V
INL,SHDN
I
QSHDN
V
CS
SHDN
= low
V
CS
= I
OUT
x R
CS
(Note 3)
V
FAULT
= 5V, OUT in regulation
I
OUT
> I
LIMIT
, or V
OUT
< V
TH
, I
FAULT
= 1mA
I
OUT
> I
LIMIT
V
OUT
< V
TH
I
OUT
< I
LIMIT
and V
OUT
> 4.5V
0.5
2
30
16
1
200
1.5
55
0.1
60
SYMBOL
V
IN
I
OUT
= 70mA
Rising edge
Falling edge
0
≤
I
OUT
< 30mA, 2.95V < V
IN
< 5.5V
0mA
≤
I
OUT
≤
125mA, 2.95V
≤
V
IN
≤
4.25V
0mA
≤
I
OUT
≤
125mA
V
OUT
= 5V (nominal), no load
V
OUT
= 5V
±4%
I
OUT
= 0, V
IN
= 4.25V
I
OUT
= 0, V
IN
= 3.3V
2.4
0.4
10
73
1
0.4
82.5
100
140
0.6
1
6
6
4.75
4.75
CONDITIONS
I
OUT
= 125mA, 4.75V
≤
V
OUT
≤
5.25V
MIN
2.95
2.95
2.0
2.35
100
5.0
5.0
100
92.5
5.30
5.25
TYP
MAX
4.25
5.50
2.6
UNITS
V
V
mV
V
mV
%V
OUT
mA
mA
V
V
µA
mV
µA
V
ms
µs
ms
MHz
µs
2
_______________________________________________________________________________________
Regulated 5V USB Charge Pump with
Programmable Current Limit
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
=
SHDN
= 3V, C
IN
= 4.7µF, C
X
= 0.68µF, C
EXT
= 6.8µF, C
OUT
= 4.7µF, R
CS
= 0.4Ω, T
A
= 0°C to +70°C, unless otherwise noted.
Typical values are at T
A
= +25°C.)
PARAMETER
Thermal Shutdown
Junction Temperature
Thermal Shutdown Hysteresis
SYMBOL
CONDITIONS
MIN
TYP
150
30
MAX
UNITS
°C
°C
MAX5008
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 +25°C and +70°C, and guaranteed by design at 0°C.
I
OUT
is output current flowing from C
EXT
.
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.
Note 1:
Note 2:
Note 3:
Note 4:
Typical Operating Characteristics
(V
IN
= 3V, C
IN
= 4.7µF, C
X
= 0.47µF, C
OUT
= 4.7µF, C
EXT
= 4.7µF, R
CS
= 0.4Ω, T
A
= +25°C, unless otherwise noted.)
NO-LOAD SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5008 toc01
OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX5008 toc02
OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
I
LOAD
= 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
V
IN
= 5.0V
5.1
1.0
4.9
V
IN
= 2.9V
4.7
V
IN
= 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)
_______________________________________________________________________________________
3
Regulated 5V USB Charge Pump with
Programmable Current Limit
MAX5008
Typical Operating Characteristics (continued)
(V
IN
= 3V, C
IN
= 4.7µF, C
X
= 0.47µF, C
OUT
= 4.7µF, C
EXT
= 4.7µF, R
CS
= 0.4Ω, T
A
= +25°C, 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)
V
IN
= 3.3V
10mV/div
0
5V
0
SHDN
V
IN
= 2.95V
MAX5008 toc04
OUTPUT WAVEFORM
MAX5008 toc05
SHUTDOWN TIMING
MAX5008 toc06
100
R
L
= 46Ω
5V
V
OUT
LINE-TRANSIENT RESPONSE
MAX5008 toc07
LOAD-TRANSIENT RESPONSE
MAX5008 toc08
I
LOAD
= 100mA
A
3.6V
3.1V
100mA
A
10mA
B
B
40µs/div
A: INPUT VOLTAGE: 500mV/div
B: OUTPUT VOLTAGE: AC-COUPLED, 100mV/div
40µs/div
A: LOAD CURRENT
B: OUTPUT VOLTAGE: AC-COUPLED, 100mV/div
4
_______________________________________________________________________________________
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. I
LIMIT
= 60mV / R
CS
.
Fixed 5V Output. Bypass OUT to GND with a 4.7µF capacitor.
Output Fault Indicator.
FAULT
is asserted when either I
OUT
> I
LIMIT
or V
OUT
< V
TH
.
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 0.68µF capacitor from CXN to CXP.
Input Supply, 2.95V to 5.5V. Bypass IN to GND with a 4.7µF ceramic capacitor.
Positive Terminal of the Charge-Pump Capacitor. Connect a 0.68µF capacitor from CXP to CXN.
Charge-Pump Output. Bypass CEXT to PGND with a 6.8µF 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-imped-
ance state and drops to ground if loaded. Placing the
device in shutdown mode reduces the supply current
to less than 0.1µA. In normal operation,
SHDN
is driven
high or connected to IN.
Adjustable Current Limit
The MAX5008 has an adjustable overcurrent protec-
tion. An external current-sense resistor is connected
from RCS to OUT to set the current limit. The current
limit is defined by:
I
LIMIT
= V
CS
/ RCS
where V
CS
is the current-sense trip level, typically 60mV.
For example, I
LIMIT
= 150mA when RCS = 0.40Ω.
When the output current limit is exceeded, the output
voltage falls and the device maintains the average out-
put current at I
LIMIT
. 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 dis-
sipation limits.
FAULT
Indication
When I
OUT
> I
LIMIT
or V
OUT
< V
TH
,
FAULT
asserts.
FAULT
is an open-drain output that needs to be con-
nected through a 100kΩ (typ) pullup resistor to a logic
supply voltage.
Table 1. Recommended Capacitor Values
I
OUT
50mA
125mA
C
IN
(µF)
3.3
4.7
C
X
(µF)
0.33
0.68
C
EXT
(µF)
3.3
6.8
C
OUT
(µF)
3.3
4.7
Thermal Shutdown
The MAX5008 has internal thermal shutdown circuitry,
which shuts down the device when the die temperature
exceeds +150°C. The thermal shutdown circuitry has
30°C hysteresis.
Layout Considerations
All capacitors should be located as close to the IC as
practical. Connect GND and PGND through a short,
5
_______________________________________________________________________________________
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