19-2918; Rev 1; 1/04
PWM Step-Down DC-DC Converters with 75m
Ω
Bypass FET for WCDMA and cdmaOne Handsets
General Description
The MAX8506/MAX8507/MAX8508 integrate a PWM step-
down DC-DC regulator and a 75mΩ (typ) bypass FET to
power the PA in WCDMA and cdmaOne™ cell phones.
The supply voltage range is from 2.6V to 5.5V, and the
guaranteed output current is 600mA. One megahertz
PWM switching allows for small external components.
The MAX8506 and MAX8507 are dynamically controlled
to provide varying output voltages from 0.4V to 3.4V. The
MAX8508 is externally programmed for fixed 0.75V to
3.4V output. Digital logic enables a high-power (HP)
bypass mode that connects the output directly to the bat-
tery for all versions. The MAX8506/MAX8507/MAX8508
are designed so the output settles in less than 30µs for a
full-scale change in output voltage and load current.
The MAX8506/MAX8507/MAX8508 are offered in 16-pin
4mm x 4mm thin QFN packages (0.8mm max height).
♦
Integrated 75mΩ (typ) Bypass FET
♦
38mV Dropout at 600mA Load
♦
Up to 94% Efficiency
♦
Dynamically Adjustable Output from 0.4V to 3.4V
(MAX8506, MAX8507)
♦
Externally Fixed Output from 0.75V to 3.4V
(MAX8508)
♦
1MHz Fixed-Frequency PWM Switching
♦
600mA Guaranteed Output Current
♦
Shutdown Mode 0.1µA (typ)
♦
16-Pin Thin QFN (4mm x 4mm, 0.8mm max Height)
Features
MAX8506/MAX8507/MAX8508
Applications
WCDMA/NCDMA Cell Phones
Wireless PDAs, Palmtops, and Notebook
Computers
Wireless Modems
cdmaOne is a trademark of CDMA Development Group.
PART
MAX8506ETE
MAX8507ETE
MAX8508ETE
Ordering Information
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 Thin QFN
16 Thin QFN
16 Thin QFN
Pin Configurations appear at end of data sheet.
Typical Application Circuits (MAX8506/MAX8507)
INPUT
2.6V TO 5.5V
2.2µF
BATTP
SKIP
SHDN
REF
0.22µF
1MHz
OSC
0.3Ω
HP
REF
PWM
0.4Ω
CURRENT-
LIMIT
CONTROL
REFIN
DAC
LX
BATT
0.075Ω
OUT
4.7µH
OUTPUT
0.4V TO 3.4V OR V
BATT
4.7µF
MAX8506
MAX8507
COMP
PGND
GND
R
C
*
C
f
*
C
C
*
* R
C
(kΩ) C
C
(pF)
MAX8506
1500
10
MAX8507
1000
15
C
f
(pF)
100
100
Typical Application Circuits continued at end of data sheet.
________________________________________________________________
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.
PWM Step-Down DC-DC Converters with 75m
Ω
Bypass FET for WCDMA and cdmaOne Handsets
MAX8506/MAX8507/MAX8508
ABSOLUTE MAXIMUM RATINGS
BATTP, BATT, OUT,
SHDN, SKIP,
HP, REFIN,
FB to GND ...........................................................-0.3V to +6V
PGND to GND .......................................................-0.3V to +0.3V
BATT to BATTP......................................................-0.3V to +0.3V
OUT, COMP, REF to GND.......................-0.3V to (V
BATT
+ 0.3V)
LX Current (Note 1) ...............................................................1.6A
OUT Current (Note 1)............................................................3.2A
Output Short-Circuit Duration.....................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
16-Pin Thin QFN (derate 16.9mW/°C above +70°C) ...1.349W
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1:
LX has internal clamp diodes to PGND and BATT. Applications that forward bias these diodes should take care not to exceed
the IC’s package power-dissipation limits.
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
BATT
= V
BATTP
= 3.6V,
SHDN
=
SKIP
= BATT, HP = GND, V
REFIN
= 1.932V (MAX8506), V
REFIN
= 1.70V (MAX8507),
C
REF
= 0.22µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
Input BATT Voltage
Undervoltage Lockout Threshold
Undervoltage Lockout Hysteresis
Quiescent Current
Quiescent Current in Dropout
Shutdown Supply Current
SKIP
= GND (normal mode)
SKIP
= BATT, 1MHz switching
HP = BATT
SHDN
= GND
V
REFIN
= 1.932V, I
OUT
= 0 to 600mA (MAX8506)
OUT Voltage Accuracy
V
REFIN
= 0.426V, I
OUT
= 0 to 30mA (MAX8506)
V
REFIN
= 1.700V, I
OUT
= 0 to 600mA (MAX8507)
V
REFIN
= 0.375V, I
OUT
= 0 to 30mA (MAX8507)
OUT Input Resistance
REFIN Input Current
REFIN to OUT Gain
Reference Voltage
Reference Load Regulation
Reference Bypass Capacitor
FB Voltage Accuracy
FB Input Current
P-Channel On-Resistance
N-Channel On-Resistance
HP/Bypass P-Channel
On-Resistance
FB = COMP (MAX8508)
V
FB
= 1V (MAX8508)
I
LX
= 180mA
I
LX
= 180mA
V
BATT
= 3.6V
V
BATT
= 2.6V
V
BATT
= 3.6V
V
BATT
= 2.6V
10µA < I
REF
< 100µA
0.1
0.7275
MAX8506
MAX8507
1.225
MAX8506
MAX8507
3.375
0.740
3.375
0.740
250
275
-1
V
BATT
rising
CONDITIONS
MIN
2.6
2.150
2.35
40
180
1750
775
0.1
3.40
0.75
3.40
0.75
485
535
0.1
1.76
2.00
1.25
2.5
0.22
0.75
0.03
0.4
0.5
0.3
0.35
0.075
0.110
0.5
0.7725
0.175
0.825
1.275
8.5
+1
1000
5
3.425
0.760
3.425
0.760
kΩ
µA
V/V
V
mV
µF
V
µA
Ω
Ω
Ω
V
250
TYP
MAX
5.5
2.575
UNITS
V
V
mV
µA
µA
µA
I
OUT
= 180mA, V
BATT
= 3.6V
2
_______________________________________________________________________________________
PWM Step-Down DC-DC Converters with 75m
Ω
Bypass FET for WCDMA and cdmaOne Handsets
ELECTRICAL CHARACTERISTICS (continued)
(V
BATT
= V
BATTP
= 3.6V,
SHDN
=
SKIP
= BATT, HP = GND, V
REFIN
= 1.932V (MAX8506), V
REFIN
= 1.70V (MAX8507),
C
REF
= 0.22µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
P-Channel Current-Limit
Threshold
N-Channel Current-Limit
Threshold
P-Channel Pulse-Skipping
Current Threshold
HP/Bypass P-Channel
Current-Limit Threshold
LX Leakage Current
OUT Leakage Current
Maximum Duty Cycle
Minimum Duty Cycle
COMP Clamp Low Voltage
COMP Clamp High Voltage
MAX8506
Transconductance
Current-Sense Transresistance
OSCILLATOR
Internal Oscillator Frequency
LOGIC INPUTS (SHDN, HP,
SKIP)
Logic-Input High Voltage
Logic-Input Low Voltage
Logic Input Current
THERMAL SHUTDOWN
Thermal-Shutdown Temperature
Thermal-Shutdown Hysteresis
+160
15
°C
°C
V
BATT
= 2.6V to 5.5V
V
BATT
= 2.6V to 5.5V
0.1
1.6
0.4
1
V
V
µA
0.8
1
1.2
MHz
MAX8507
MAX8508
85
75
150
0.36
SKIP
= GND (normal mode)
SKIP
= BATT
0.8
2.0
150
130
260
0.48
215
188
376
0.60
V/A
µS
SKIP
= BATT (PWM mode)
SKIP
= GND (normal mode)
SKIP
= GND (normal mode)
V
OUT
= 3.1V
CONDITIONS
MIN
1.00
-0.6
0.03
0.050
0.8
-2
-2
100
0
12
TYP
1.25
-0.45
0.05
0.125
1.5
0.01
0.01
MAX
1.50
-0.30
0.07
0.170
2.5
+2
+2
UNITS
A
A
A
A
µA
µA
%
%
V
V
MAX8506/MAX8507/MAX8508
Note 2:
Specifications to -40°C are guaranteed by design, not production tested.
_______________________________________________________________________________________
3
PWM Step-Down DC-DC Converters with 75m
Ω
Bypass FET for WCDMA and cdmaOne Handsets
MAX8506/MAX8507/MAX8508
Typical Operating Characteristics
(V
BATT
= V
BATTP
= 3.6V,
SHDN
=
SKIP
= BATT, HP = GND, T
A
= +25°C, unless otherwise noted.) (See the
Typical Application Circuits.)
EFFICIENCY vs. OUTPUT VOLTAGE
IN NORMAL MODE
R
LOAD
= 15Ω
MAX8506 toc01
EFFICIENCY vs. OUTPUT VOLTAGE
IN PWM MODE
R
LOAD
= 15Ω
MAX8506 toc02
EFFICIENCY vs. INPUT VOLTAGE
MAX8506 toc03
100
100
100
90
EFFICIENCY (%)
R
LOAD
= 10Ω
R
LOAD
= 5Ω
90
EFFICIENCY (%)
R
LOAD
= 10Ω
R
LOAD
= 5Ω
90
V
OUT
= 3.4V
EFFICIENCY (%)
80
80
80
V
OUT
= 1.2V
70
70
70
60
SKIP = GND
50
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
OUTPUT VOLTAGE (V)
60
60
V
OUT
= 0.4V
SKIP = GND
R
LOAD
= 10Ω
2.5
3.0
3.5
4.0
4.5
5.0
5.5
50
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
OUTPUT VOLTAGE (V)
50
INPUT VOLTAGE (V)
EFFICIENCY vs. LOAD CURRENT
MAX8506 toc04
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX8506 toc05
SUPPLY CURRENT vs. SUPPLY VOLTAGE
IN PWM MODE
MAX8506 toc06
100
V
OUT
= 2.5V;
NORMAL MODE
90
EFFICIENCY (%)
150
V
IN
= 3.6V
HP = BATT
120
OUTPUT VOLTAGE (mV)
6
5
SUPPLY CURRENT (mA)
4
3
2
1
0
V
OUT
= 1.2V
V
OUT
= 0.4V
80
V
OUT
= 1.2V;
PWM
V
OUT
= 2.5V;
PWM
60
V
OUT
= 1.2V;
NORMAL MODE
1
10
100
1000
90
70
60
30
50
LOAD CURRENT (mA)
0
0
500
1000
1500
2000
LOAD CURRENT (mA)
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
IN NORMAL MODE
900
SUPPLY CURRENT (µA)
800
700
600
500
400
300
200
100
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
V
OUT
= 1.2V
V
OUT
= 0.4V
V
OUT
= 3.4V
SKIP = GND
MAX8506 toc07
HEAVY-LOAD SWITCHING WAVEFORM
MAX8506 toc08
1000
V
LX
2V/div
V
OUT
AC-COUPLED
20mV/div
V
OUT
= 1.2V
LOAD = 10Ω
1µs/div
4
_______________________________________________________________________________________
PWM Step-Down DC-DC Converters with 75m
Ω
Bypass FET for WCDMA and cdmaOne Handsets
MAX8506/MAX8507/MAX8508
Typical Operating Characteristics (continued)
(V
BATT
= V
BATTP
= 3.6V,
SHDN
=
SKIP
= BATT, HP = GND, T
A
= +25°C, unless otherwise noted.) (See the
Typical Application Circuits.)
LIGHT-LOAD SWITCHING WAVEFORM
IN PWM MODE
MAX8506 toc09
LIGHT-LOAD SWITCHING WAVEFORM
IN NORMAL MODE
MAX8506 toc10
V
LX
2V/div
V
LX
2V/div
V
OUT
AC-COUPLED
5mV/div
V
OUT
= 0.4V
LOAD = 10Ω
400µs/div
V
OUT
= 0.4V
LOAD = 10Ω, SKIP = GND
1µs/div
V
OUT
AC-COUPLED
20mV/div
EXITING AND ENTERING SHUTDOWN
MAX8506 toc11
REFIN TRANSIENT RESPONSE
MAX8506 toc12
SHDN
2V/div
0
SKIP = GND
REFIN
1V/div
V
OUT
1V/div
0
V
OUT
= 1.8V, R
LOAD
= 10Ω
100µs/div
V
OUT
1V/div
SKIP = BATT
V
REFIN
= 0.284V TO 1.420V
20µs/div
HP TRANSIENT RESPONSE
MAX8506 toc13
LINE TRANSIENT RESPONSE
MAX8506 toc14
HP
1V/div
0
3.4V
SKIP = GND
V
OUT
1V/div
1.8V
SKIP = BATT
V
OUT
= 1.8V, R
LOAD
= 10Ω
20µs/div
V
IN
200mV/div
V
OUT
AC-COUPLED
20mV/div
V
OUT
= 1.2V, R
LOAD
= 10Ω
20µs/div
_______________________________________________________________________________________
5
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