General Description
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
high-frequency step-down converters are optimized for
dynamically powering the power amplifier (PA) in
WCDMA or NCDMA handsets. The devices integrate a
high-efficiency PWM step-down converter for medium-
and low-power transmission, and a 60mΩtypical
bypass FET to power the PA directly from the battery
during high-power transmission. Dual 200mA low-noise,
high-PSRR low-dropout regulators (LDOs) for PA bias-
ing are also integrated.
Two switching frequency options are available (2MHz for
the MAX8805W/MAX8805Y and 4MHz for the MAX8805X/
MAX8805Z), allowing optimization for smallest solution
size or highest efficiency. Fast switching allows the use of
small ceramic 2.2µF input and output capacitors while
maintaining low ripple voltage. The feedback network is
integrated, further reducing external component count
and total solution size.
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z use
an analog input driven by an external DAC to control
the output voltage linearly for continuous PA power
adjustment. The REFIN to OUT gain is available in two
options (2V/V for the MAX8805Y/MAX8805Z and 2.5V/V
for the MAX8805W/MAX8805X). At high-duty cycle, the
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z auto-
matically switch to the bypass mode, connecting the
input to the output through a low-impedance (60mΩ
typ) MOSFET. The user can also enable the bypass
mode directly through a logic-control input.
The LDOs in the MAX8805W/MAX8805X/MAX8805Y/
MAX8805Z are designed for low-noise operation
(35µVRMS typ). Each LDO is individually enabled
through its own logic control interface.
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z are
available in a 16-bump, 2mm x 2mm WLP package
(0.7mm max height).
Features
oPA Step-Down Converter
7.5µs (typ) Settling Time for 0.8V to 3.4V Output
Voltage Change
Dynamic Output Voltage Setting from 0.4V to
VBATT
60mΩpFET and 100% Duty Cycle for Low
Dropout
2MHz or 4MHz Switching Frequency
Low Output-Voltage Ripple
600mA (MAX8805Y/MAX8805Z) or 650mA
(MAX8805W/MAX8805X) Output Drive
Capability
2% Gain Accuracy
Tiny External Components
oDual Low-Noise LDOs
Low 35µVRMS (typ) Output Noise
High 70dB (typ) PSRR
Guaranteed 200mA Output Drive Capability
Individual ON/OFF Control
oLow 0.1µA Shutdown Current
o2.7V to 5.5V Supply Voltage Range
oThermal Shutdown
oTiny 2mm x 2mm x 0.7mm WLP Package
(4 x 4 Grid)
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
________________________________________________________________
Maxim Integrated Products
1
Ordering Information
19-0777; Rev 4; 9/08
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
+
Denotes a lead-free/RoHS-compliant package.
T = Tape and reel.
*
xy is the output voltage code (see Table 1).
Note: All devices are specified over the -40°C to +85°C operating temperature range.
Pin Configuration appears at end of data sheet.
EVALUATION KIT
AVAILABLE
PART PIN-
PACKAGE SWITCHING FREQUENCY REFIN TO OUT GAIN
MAX8805WEWExy+T* 16 WLP 2MHz 2.5V/V
MAX8805XEWExy+T* 16 WLP 4MHz 2.5V/V
MAX8805YEWExy+T* 16 WLP 2MHz 2V/V
MAX8805ZEWExy+T* 16 WLP 4MHz 2V/V
Applications
WCDMA/NCDMA Cellular Handsets
Wireless PDAs
Smartphones
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN1A = VIN1B = VIN2 = VPA_EN = VEN1 = VEN2 = 3.6V, VHP = 0V, VREFIN = 0.9V (MAX8805Y/MAX8805Z), VREFIN = 0.72V
(MAX8805W/MAX8805X), TA= -40°C to +85°C. Typical values are at TA=+25°C, unless otherwise noted.) (Note 1)
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.
IN1A, IN1B, IN2, REFIN, EN2, REFBP to AGND ...-0.3V to +6.0V
PAA, PAB, PA_EN, HP to AGND....-0.3V to (VIN1A/VIN1B + 0.3V)
LDO1, LDO2, EN1 to AGND ......................-0.3V to (VIN2 + 0.3V)
IN2 to IN1B/IN1A ...................................................-0.3V to +0.3V
PGND to AGND .....................................................-0.3V to +0.3V
LX Current ......................................................................0.7ARMS
IN1A/IN1B and PAA/PAB Current .....................................2ARMS
PAA and PAB Short Circuit to GND or IN...................Continuous
Continuous Power Dissipation (TA= +70°C)
16-Bump WLP (derate 12.5mW/°C above +70°C).............1W
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Bump Temperature (soldering, reflow) ............................+260°C
PARAMETER CONDITIONS MIN TYP MAX UNITS
INPUT SUPPLY
Input Voltage VIN1A, VIN1B, VIN2 2.7 5.5 V
Input Undervoltage Threshold VIN1A, VIN1B, VIN2 rising, 180mV typical hysteresis 2.52 2.63 2.70 V
TA = +25°C 0.1 4
Shutdown Supply Current VPA_EN = VEN1 = VEN2 = 0V TA = +85°C 0.1 µA
VPA_EN = 0V, ILDO1 = ILDO2 = 0mA 150 250
MAX8805W/MAX8805Y 3500
VEN1 = VEN2 = 0V, IPA = 0mA,
switching MAX8805X/MAX8805Z 5000
No-Load Supply Current
VEN1 = VEN2 = 0V, VHP = 3.6V 150
µA
THERMAL PROTECTION
Thermal Shutdown TA rising, 20°C typical hysteresis +160 °C
LOGIC CONTROL
PA_EN, EN1, EN2, HP Logic-
Input High Voltage 2.7V ≤ VIN1A = VIN1B = VIN2 ≤ 5.5V 1.4 V
PA_EN, EN1, EN2, HP Logic-
Input Low Voltage 2.7V ≤ VIN1A = VIN1B = VIN2 ≤ 5.5V 0.4 V
TA = +25°C 0.01 1
Logic-Input Current
(PA_EN, EN1, EN2, HP) VIL = 0V or VIH = VIN1A = 5.5V TA = +85°C 0.1 µA
REFIN
MAX8805Y/MAX8805Z 0.1 2.2
REFIN Common-Mode Range MAX8805W/MAX8805X 0.1 1.76 V
VREFIN = 0.4V, 0.9V, 1.7V,
2.2V (ILX = 0mA) MAX8805Y/MAX8805Z 1.96 2.00 2.04
REFIN to PA_ Gain VREFIN = 0.32V, 0.75V,
1.32V, 1.76V (ILX = 0mA) MAX8805W/MAX8805X 2.45 2.50 2.55
V/V
MAX8805Y/MAX8805Z 540
REFIN Input Resistance MAX8805W/MAX8805X 320 kΩ
Note: This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device
can be exposed to during board level solder attach and rework. This limit permits only the use of the solder profiles recom-
mended in the industry-standard specification, JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and Convection reflow.
Preheating is required. Hand or wave soldering is not allowed.
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
_______________________________________________________________________________________ 3
PARAMETER CONDITIONS MIN TYP MAX UNITS
MAX8805Y/MAX8805Z 0.44 x
VIN2
0.465 x
VIN2
0.48 x
VIN2
REFIN
Dual Mode™ Threshold VREFIN rising, 50mV hysteresis
MAX8805W/MAX8805X 0.36 x
VIN2
0.372 x
VIN2
0.39 x
VIN2
V
LX
p-channel MOSFET switch, ILX = -40mA 0.18 0.6
On-Resistance n-channel MOSFET rectifier, ILX = 40mA 0.15 0.6 Ω
TA = +25°C 0.1 5
LX Leakage Current VIN1A = VIN1B = VIN2 = 5.5V,
VLX = 0V TA = +85°C 1 µA
MAX8805Y/MAX8805Z 0.7 0.9 1.1
Peak Current Limit
(p-Channel MOSFET) VLX = 0V MAX8805W/MAX8805X 0.75 0.95 1.15 A
MAX8805Y/MAX8805Z 0.5 0.7 0.9
Valley Current Limit
(n-Channel MOSFET) MAX8805W/MAX8805X 0.55 0.75 0.95 A
MAX8805Y/MAX8805Z 0.1
Minimum On- and Off-Times MAX8805W/MAX8805X 0.07 µs
Power-Up Delay From PA_EN rising to LX rising 150 250 µs
BYPASS
TA = +25°C 0.060 0.1
On-Resistance p-channel MOSFET bypass,
IOUT = -90mA TA = +85°C 0.1 Ω
Bypass Current Limit VPA = 0V 0.8 1.2 1.8 A
MAX8805Y/MAX8805Z 0.7 0.9 1.1
S tep - D ow n C ur r ent Li m i t i n Byp ass VLX = 0V MAX8805W/MAX8805X 0.75 0.95 1.15 A
MAX8805Y/MAX8805Z 1.5 2.1 2.9
Total Bypass Current Limit VLX = VPA = 0V MAX8805W/MAX8805X 1.55 2.15 2.95 A
TA = +25°C 0.01 10
Bypass Off-Leakage Current VIN1A = VIN1B = VIN2 = 5.5V,
VPAA = VPAB = 0V TA = +85°C1
µA
LDO1
MAX8805_EWEAA+T 1.746 1.8 1.854
MAX8805_EWEBC+T 2.425 2.5 2.575
MAX8805_EWECC+T 2.619 2.7 2.781
MAX8805_EWEDD+T 2.716 2.8 2.884
MAX8805_EWEEE+T 2.765 2.85 2.936
Output Voltage VLDO1 VIN2 = 5.5V, ILDO1 = 1mA;
VIN2 = 3.4V, ILDO1 = 100mA
MAX8805_EWEGG+T 2.910 3.0 3.090
V
Output Current 200 mA
Current Limit VLDO1 = 0V 250 550 750 mA
Dropout Voltage ILDO1 = 100mA, TA = +25°C (VLDO1 ≥ 2.5V) 70 200 mV
Line Regulation VIN2 stepped from 3.5V to 5.5V, ILDO1 = 100mA 2.4 mV
Load Regulation ILDO1 stepped from 50µA to 200mA 25 mV
Power-Supply Rejection 10Hz to 10kHz, CLDO1 = 1µF, ILDO1 = 30mA 70 dB
ELECTRICAL CHARACTERISTICS (continued)
(VIN1A = VIN1B = VIN2 = VPA_EN = VEN1 = VEN2 = 3.6V, VHP = 0V, VREFIN = 0.9V (MAX8805Y/MAX8805Z), VREFIN = 0.72V
(MAX8805W/MAX8805X), TA= -40°C to +85°C. Typical values are at TA=+25°C, unless otherwise noted.) (Note 1)
Dual Mode is a trademark of Maxim Integrated Products, Inc.
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VIN1A = VIN1B = VIN2 = VPA_EN = VEN1 = VEN2 = 3.6V, VHP = 0V, VREFIN = 0.9V (MAX8805Y/MAX8805Z), VREFIN = 0.72V
(MAX8805W/MAX8805X), TA= -40°C to +85°C. Typical values are at TA=+25°C, unless otherwise noted.) (Note 1)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Noise 100Hz to 100kHz, CLDO1 = 1µF, ILDO1 = 30mA 35 µVRMS
0 < ILDO1 < 10mA 100 nF
Output Capacitor for Stable
Operation 0 < ILDO1 < 200mA 1 µF
Shutdown Output Impedance VEN1 = 0V 1 kΩ
LDO2
MAX8805_EWEAA+T 1.746 1.8 1.854
MAX8805_EWEAC+T 2.619 2.7 2.781
MAX8805_EWEAD+T 2.716 2.8 2.884
MAX8805_EWEBE+T 2.765 2.85 2.936
Output Voltage VLDO2 VIN2 = 5.5V, ILDO2 = 1mA;
VIN2 = 3.4V, ILDO2 = 100mA
MAX8805_EWEGG+T 2.910 3.0 3.090
V
Output Current 200 mA
Current Limit VLDO2 = 0V 250 550 750 mA
Dropout Voltage ILDO2 = 100mA, TA = +25°C 70 200 mV
Line Regulation VIN2 stepped from 3.5V to 5.5V, ILDO2 = 100mA 2.4 mV
Load Regulation ILDO2 stepped from 50µA to 200mA 25 mV
Power-Supply Rejection
ΔVLDO2 / ΔVIN2 10Hz to 10kHz, CLDO2 = 1µF, ILDO2 = 30mA 70 dB
Output Noise 100Hz to 100kHz, CLDO2 = 1µF, ILDO2 = 30mA 35 µVRMS
0µA < ILDO2 < 10mA 100 nF
Output Capacitor for Stable
Operation 0µA < ILDO2 < 200mA 1 µF
Shutdown Output Impedance VEN2 = 0V 1 kΩ
REFBP
REFBP Output Voltage 0 ≤ IREFBP ≤ 1µA 1.237 1.250 1.263 V
REFBP Supply Rejection VIN2 stepped from 2.55V to 5.5V 0.2 5 mV
Note 1: All devices are 100% production tested at TA= +25°C. Limits over the operating temperature range are guaranteed by design.
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
_______________________________________________________________________________________
5
Typical Operating Characteristics
(VIN1A = VIN1B = VIN2 = 3.6V, VPA = 1.2V, VLDO1 = 2.85V, VLDO2 = 2.85V, RPA = 7.5Ω, circuit of Figure 5, TA= +25°C, unless other-
wise noted.)
0
40
20
80
60
120
100
140
0 0.4 0.60.2 0.8 1.0 1.2 1.4 1.6 1.8
BYPASS MODE DROPOUT VOLTAGE
vs. PA LOAD CURRENT
MAX8805W/X/Y/Z toc01
PA LOAD CURRENT (A)
BYPASS MODE DROPOUT VOLTAGE (mV)
VIN1 = 3.2V
VIN1 = 3.6V
60
70
80
90
100
0.5 1.5 2.5 3.51.0 2.0 3.0 4.0 4.5
PA STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT VOLTAGE (MAX8805X/MAX8805Z)
MAX8805W/X/Y/Z toc02
OUTPUT VOLTAGE (V)
EFFICIENCY (%)
BYPASS MODE
VIN1 = 4.2V
VIN1 = 3.6V
VIN1 = 3.2V
RPA = 7.5Ω
60
70
80
90
100
0.5 1.5 2.5 3.51.0 2.0 3.0 4.0 4.5
PA STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT VOLTAGE (MAX8805W/MAX8805X)
MAX8805W/X/Y/Z toc03
OUTPUT VOLTAGE (V)
EFFICIENCY (%)
BYPASS MODE
VIN1 = 4.2V
VIN1 = 3.6V
VIN1 = 3.2V
RPA = 7.5Ω
60
70
80
90
100
0.5 1.5 2.5 3.51.0 2.0 3.0 4.0 4.5
PA STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT VOLTAGE (MAX8805X/MAX8805Z)
MAX8805W/X/Y/Z toc04
OUTPUT VOLTAGE (V)
EFFICIENCY (%)
BYPASS MODE
VIN1 = 4.2V
VIN1 = 3.6V
VIN1 = 3.2V
RPA = 10Ω
60
70
80
90
100
0.5 1.5 2.5 3.51.0 2.0 3.0 4.0 4.5
PA STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT VOLTAGE (MAX8805W/MAX8805Y)
MAX8805W/X/Y/Z toc05
OUTPUT VOLTAGE (V)
EFFICIENCY (%)
BYPASS MODE
VIN1 = 4.2V
VIN1 = 3.6V
VIN1 = 3.2V
RPA = 10Ω
50
60
80
70
90
100
0200100 300 400 500 600 700
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805X/MAX8805Z)
MAX8805W/X/Y/Z toc06
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN1 = 3.2V
VPA = 1.8V
VIN1 = 3.6V VIN1 = 4.2V
50
60
80
70
90
100
0 200100 300 400 500 600 700
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805W/MAX8805Y)
MAX8805W/X/Y/Z toc07
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN1 = 3.2V
VPA = 1.8V
VIN1 = 3.6V
VIN1 = 4.2V
50
60
80
70
90
100
0 200100 300 400 500 600 700
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805X/MAX8805Z)
MAX8805W/X/Y/Z toc08
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN1 = 3.2V
VPA = 1.2V
VIN1 = 3.6V
VIN1 = 4.2V
50
60
80
70
90
100
0 200100 300 400 500 600 700
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805W/MAX8805Y)
MAX8805W/X/Y/Z toc09
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN1 = 3.2V
VPA = 1.2V
VIN1 = 3.6V
VIN1 = 4.2V
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
6 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VIN1A = VIN1B = VIN2 = 3.6V, VPA = 1.2V, VLDO1 = 2.85V, VLDO2 = 2.85V, RPA = 7.5Ω, circuit of Figure 5, TA= +25°C, unless other-
wise noted.)
50
60
80
70
90
100
0200100 300 400 500 600 700
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805W/MAX8805Y)
MAX8805W/X/Y/Z toc11
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN1 = 3.2V
VPA = 0.6V
VIN1 = 3.6V
VIN1 = 4.2V
1.25
1.20
1.15
1.10
1.05
0 300100 200 400 500 600 700
PA STEP-DOWN CONVERTER OUTPUT
VOLTAGE vs. LOAD CURRENT
MAX8805W/X/Y/Z toc12
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
MAX8805X/MAX8805Z
MAX8805W/MAX8805Y
0.5
1.5
1.0
2.5
2.0
3.5
3.0
4.0
0 0.80.4 1.2 1.6 2.0
PA STEP-DOWN CONVERTER OUTPUT
VOLTAGE vs. REFIN VOLTAGE
MAX8805Y/Z toc13
REFIN VOLTAGE (V)
OUTPUT VOLTAGE (V)
MAX8805X/MAX8805W
MAX8805Y/MAX8805Z
-100
-60
-80
0
-20
-40
20
40
80
60
100
0.4 0.6 0.70.5 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5
REFIN vs. REFIN TO OUT GAIN (MAX8805Z)
MAX8805Y/Z toc14
REFIN VOLTAGE (V)
OUTPUT VOLTAGE ERROR (mV)
VIN1 = 3.2V, NO LOAD
VIN1 = 4.2V, NO LOAD
-50
-30
-10
10
30
50
0.4 0.6 0.70.5 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5
REFIN vs. REFIN TO OUT GAIN (MAX8805Y)
MAX8805Y/Z toc15
REFIN VOLTAGE (V)
OUTPUT VOLTAGE ERROR (mV)
VIN1 = 3.2V, NO LOAD
VIN1 = 4.2V, NO LOAD
-50
-30
-10
10
30
50
0.4 0.7 0.80.5 0.6 0.9 1.0 1.1 1.2 1.3
REFIN vs. REFIN TO OUT GAIN (MAX8805X)
MAX8805W/X/Y/Z toc16
REFIN VOLTAGE (V)
OUTPUT VOLTAGE ERROR (mV)
VIN1 = 3.2V, NO LOAD
VIN1 = 4.2V, NO LOAD
-50
-30
-10
10
30
50
0.4 0.7 0.80.5 0.6 0.9 1.0 1.1 1.2 1.3
REFIN vs. REFIN TO OUT GAIN (MAX8805W)
MAX8805W/X/Y/Z toc17
REFIN VOLTAGE (V)
OUTPUT VOLTAGE ERROR (mV)
VIN1 = 3.2V, NO LOAD
VIN1 = 4.2V, NO LOAD
400ns/div
PA STEP-DOWN CONVERTER LIGHT-LOAD
SWITCHING WAVEFORMS (MAX8805X/MAX8805Z)
VPA
AC-COUPLED
ILX 200mA/div
20mV/div
2V/div
MAX8805W/X/Y/Z toc18
VLX
VPA = 1.2V, IPA = 50mA
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
_______________________________________________________________________________________
7
400ns/div
PA STEP-DOWN CONVERTER LIGHT-LOAD
SWITCHING WAVEFORMS (MAX8805W/MAX8805Y)
VPA
AC-COUPLED
ILX 200mA/div
20mV/div
2V/div
MAX8805W/X/Y/Z toc19
VLX
VPA = 1.2V, IPA = 50mA
400ns/div
PA STEP-DOWN HEAVY-LOAD
SWITCHING WAVEFORMS (MAX8805X/MAX8805Z)
VPA
AC-COUPLED
ILX 500mA/div
20mV/div
2V/div
MAX8805W/X/Y/Z toc20
VLX
VPA = 1.2V, IPA = 500mA
400ns/div
PA STEP-DOWN HEAVY-LOAD
SWITCHING WAVEFORMS (MAX8805W/MAX8805Y)
VPA
AC-COUPLED
ILX 500mA/div
20mV/div
2V/div
MAX8805W/X/Y/Z toc21
VLX
VPA = 1.2V, IPA = 500mA
Typical Operating Characteristics (continued)
(VIN1A = VIN1B = VIN2 = 3.6V, VPA = 1.2V, VLDO1 = 2.85V, VLDO2 = 2.85V, RPA = 7.5Ω, circuit of Figure 5, TA= +25°C, unless other-
wise noted.)
_______________________________________________________________________________________
7
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
8 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VIN1A = VIN1B = VIN2 = 3.6V, VPA = 1.2V, VLDO1 = 2.85V, VLDO2 = 2.85V, RPA = 7.5Ω, circuit of Figure 5, TA= +25°C, unless other-
wise noted.)
10μs/div
PA STEP-DOWN CONVERTER LOAD
TRANSIENT RESPONSE (MAX8805X/MAX8805Z)
IPA
ILX 500mA/div
500mA/div
100mV/div
MAX8805W/X/Y/Z toc26
VPA
AC-COUPLED
0mA
500mA
0mA
10μs/div
PA STEP-DOWN CONVERTER LOAD
TRANSIENT RESPONSE (MAX8805W/MAX8805Y)
IPA
ILX 500mA/div
500mA/div
100mV/div
MAX8805W/X/Y/Z toc27
VPA
AC-COUPLED
0mA
500mA
0mA
10μs/div
PA STEP-DOWN CONVERTER LINE
TRANSIENT RESPONSE (MAX8805W/MAX8805Y)
VIN1
VPA
AC-COUPLED 50mV/div
500mV/div
200mA/div
MAX8805W/X/Y/Z toc25
ILX
4.0V
3.5V
4.0V
10μs/div
PA STEP-DOWN CONVERTER LINE
TRANSIENT RESPONSE (MAX8805X/MAX8805Z)
VIN1
VPA
AC-COUPLED 50mV/div
500mV/div
200mA/div
MAX8805W/X/Y/Z toc24
ILX
4.0V
3.5V
4.0V
20μs/div
PA STEP-DOWN SOFT-START
WAVEFORMS (MAX8805X/MAX8805Z)
VPA_EN
VPA 1V/div
2V/div
500mA/div
MAX8805W/X/Y/Z toc22
ILX
20μs/div
PA STEP-DOWN SOFT-START
WAVEFORMS (MAX8805W/MAX8805Y)
VPA_EN
VPA 1V/div
2V/div
200mA/div
MAX8805W/X/Y/Z toc23
ILX
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
_______________________________________________________________________________________
9
10μs/div
PA STEP-DOWN CONVERTER OUTPUT
VOLTAGE TRANSIENT RESPONSE
(MAX8805Y/MAX8805Z)
VREFIN
VPA 500mV/div
500mV/div
500mA/div
MAX8805W/X/Y/Z toc28
ILX
0.5V
1V
0.5V
20μs/div
PA STEP-DOWN CONVERTER FORCED
BYPASS-FET TRANSIENT RESPONSE
(MAX8805Y/MAX8805Z)
VHP
VPA 2V/div
2V/div
500mA/div
MAX8805W/X/Y/Z toc29
ILX
1.5V
0V
0V
1.2V 1.2V
3.6V
10μs/div
PA STEP-DOWN CONVERTER OUTPUT
VOLTAGE TRANSIENT RESPONSE
(MAX8805W/MAX8805X)
VREFIN
VPA 500mV/div
500mV/div
500mA/div
MAX8805W/X/Y/Z toc30
ILX
1.25V
0.66V
0.66V
20μs/div
PA STEP-DOWN CONVERTER
BYPASS-FET TRANSIENT RESPONSE
(MAX8805W/MAX8805X)
VHP
VPA 2V/div
2V/div
500mA/div
MAX8805W/X/Y/Z toc31
ILX
3.6V
1.2V
2V
0V
1.2V
0V
10μs/div
PA STEP-DOWN CONVERTER AUTOMATIC
BYPASS-FET TRANSIENT RESPONSE
(MAX8805Y/MAX8805Z)
VREFIN
VPA 2V/div
1V/div
500mA/div
MAX8805W/X/Y/Z toc32
ILX
1.8V
0.6V
0.6V
1.2V 1.2V
3.6V
200μs/div
PA STEP-DOWN CONVERTER AUTOMATIC
BYPASS-FET TRANSIENT RESPONSE
(MAX8805Y/MAX8805Z)
VREFIN
VPA
1V/div
1V/div
500mA/div
MAX8805W/X/Y/Z toc33
ILX
VREFIN IS A 0.4V TO
2V SINUSOIDAL
SIGNAL
3.6V
Typical Operating Characteristics (continued)
(VIN1A = VIN1B = VIN2 = 3.6V, VPA = 1.2V, VLDO1 = 2.85V, VLDO2 = 2.85V, RPA = 7.5Ω, circuit of Figure 5, TA= +25°C, unless other-
wise noted.)
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
10 ______________________________________________________________________________________
0
50
100
150
200
LDO1, LDO2 SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX8805W/X/Y/Z toc38
SUPPLY VOLTAGE (V)
NO-LOAD SUPPLY CURRENT (μA)
2.0 3.5 4.02.5 3.0 4.5 5.0 5.5
0
30
90
60
120
150
LDO1, LDO2 DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX8805W/X/Y/Z toc39
LOAD CURRENT (mA)
LDO1, LDO2 DROPOUT VOLTAGE (mV)
010050 150 200
10μs/div
PA STEP-DOWN CONVERTER SHUTDOWN
RESPONSE (MAX8805X/MAX8805Z)
VPA_EN
VPA
2V/div
2V/div
100mA/div
MAX8805W/X/Y/Z toc37
ILX
0V
2V
1.2V
10μs/div
PA STEP-DOWN CONVERTER
BYPASS-FET TRANSIENT RESPONSE
(MAX8805W/MAX8805X)
VREFIN
VPA 2V/div
1V/div
500mA/div
MAX8805W/X/Y/Z toc34
ILX
1.2V
0.48V
3.6V
1.44V
0.48V
1.2V
200μs/div
PA STEP-DOWN CONVERTER
AUTOMATIC BYPASS-FET TRANSIENT
RESPONSE (MAX8805W/MAX8805X)
VREFIN
VPA 1V/div
1V/div
500mA/div
MAX8805W/X/Y/Z toc35
ILX
3.6V
VREFIN IS A 0.48V TO
2.1V SINSOIDAL
SIGNAL
10μs/div
PA STEP-DOWN CONVERTER SHUTDOWN
RESPONSE (MAX8805W/MAX8805Y)
VPA_EN
VPA
1V/div
2V/div
100mA/div
MAX8805W/X/Y/Z toc36
ILX
0V
2V
1.2V
Typical Operating Characteristics (continued)
(VIN1A = VIN1B = VIN2 = 3.6V, VPA = 1.2V, VLDO1 = 2.85V, VLDO2 = 2.85V, RPA = 7.5Ω, circuit of Figure 5, TA= +25°C, unless other-
wise noted.)
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
______________________________________________________________________________________
11
LDO PSRR vs. FREQUENCY
MAX8805W/X/Y/Z toc40
FREQUENCY (kHz)
PSRR (dB)
1001010.1
20
30
40
50
60
70
80
10
0.01 1000
ILDO = 30mA
LDO OUTPUT NOISE SPECTRAL DENSITY
vs. FREQUENCY
MAX8805W/X/Y/Z toc41
FREQUENCY (kHz)
OUTPUT NOISE DENSITY NOISE (nV/√Hz)
1001010.1
1.0E+02
1.0E+03
1.0E+04
1.0E+01
0.01 1000
400μs/div
LDO1, LDO2 OUTPUT NOISE WAVEFORM
50mV/div
MAX8805W/X/Y/Z toc42
20μs/div
LDO LINE TRANSIENT RESPONSE
500mV/div
MAX8805W/X/Y/Z toc43
4.0V
4.0V
3.5V
ILDO_ = 80mA
5mV/div
VIN2
VLDO_
20μs/div
LDO1, LDO2 LOAD TRANSIENT
RESPONSE NEAR DROPOUT
100mA/div
50mV/div
100mA/div
MAX8805W/X/Y/Z toc44
0mA
80mA
VIN2 = VLDO1,2 + 200mV
50mV/div
ILDO1
VLDO1
ILDO2
VLDO2
0mA
0mA 0mA
80mA
1ms/div
LDO1, LDO2 TURN ON AND
SHUTDOWN RESPONSE
2V/div
2V/div
2V/div
MAX8805W/X/Y/Z toc45
VEN1,2
VLDO1
VLDO2
Typical Operating Characteristics (continued)
(VIN1A = VIN1B = VIN2 = 3.6V, VPA = 1.2V, VLDO1 = 2.85V, VLDO2 = 2.85V, RPA = 7.5Ω, circuit of Figure 5, TA= +25°C, unless other-
wise noted.)
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
12 ______________________________________________________________________________________
Pin Description
PIN NAME FUNCTION
A1 REFBP Reference Noise Bypass. Bypass REFBP to AGND with a 0.22µF ceramic capacitor to reduce noise on the
LDO outputs. REFBP is internally pulled down through a 1kΩ resistor during shutdown.
A2 AGND Low-Noise Analog Ground
A3 REFIN
DAC-Controlled Input. The output of the PA step-down converter is regulated to 2 x VREFIN for the
MAX8805Y/MAX8805Z and 2.5 x VREFIN for the MAX8805W/MAX8805X. When VREFIN reaches 0.465 x VIN2
for the MAX8805Y/MAX8805Z and 0.372 x VIN2 for the MAX8805W/MAX8805X, bypass mode is enabled.
A4 PGND Power Ground for PA Step-Down Converter
B1 LDO2 200mA LDO Regulator 2 Output. Bypass LDO2 with a 1µF ceramic capacitor as close as possible to LDO2
and AGND. LDO2 is internally pulled down through a 1kΩ resistor when this regulator is disabled.
B2 PA_EN PA Step-Down Converter Enable Input. Connect to IN_ or logic-high for normal operation. Connect to GND
or logic-low for shutdown mode.
B3 EN2 LDO2 Enable Input. Connect to IN2 or logic-high for normal operation. Connect to AGND or logic-low for
shutdown mode.
B4 LX Inductor Connection. Connect an inductor from LX to the output of the PA step-down converter.
C1 IN2
Supply Voltage Input for LDO1, LDO2, and Internal Reference. Connect IN2 to a battery or supply voltage
from 2.7V to 5.5V. Bypass IN2 with a 2.2µF ceramic capacitor as close as possible to IN2 and AGND.
Connect IN2 to the same source as IN1A and IN1B.
C2 HP
High-Power Mode Set Input. Drive HP high to invoke forced bypass mode. Bypass mode connects the
input of the PA step-down converter directly to its output through the internal bypass MOSFET. Drive HP
low to disable the forced bypass mode.
C3, C4 IN1B,
IN1A
Supply Voltage Input for PA Step-Down Converter. Connect IN1_ to a battery or supply voltage from 2.7V to
5.5V. Bypass the connection of IN1_ with a 2.2µF ceramic capacitor as close as possible to IN1_, and
PGND. IN1A and IN1B are internally connected together. Connect IN1_ to the same source as IN2.
D1 LDO1 200mA LDO Regulator 1 Output. Bypass LDO1 with a 1µF ceramic capacitor as close as possible to LDO1
and AGND. LDO1 is internally pulled down through a 1kΩ resistor when this regulator is disabled.
D2 EN1 LDO1 Enable Input. Connect to IN2 or logic-high for normal operation. Connect to AGND or logic-low for
shutdown mode.
D3, D4 PAB, PAA
PA Connection for Bypass Mode. Internally connected to IN1_ using the internal bypass MOSFET during
bypass mode. PA_ is connected to the internal feedback network. Bypass PA_ with a 2.2µF ceramic
capacitor as close as possible to PA_ and PGND.
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
______________________________________________________________________________________ 13
PWM LOGIC
STEP-DOWN CURRENT LIMIT
PWM ERROR
COMPARATOR
CURRENT-LIMIT CONTROL
LX
PGND
PAA
BYPASS FET
HP
REFIN
R2 R1
R3
R5R4
R6
R7
C2
C1
IN2
R8
R7
ERROR AMP
ERROR AMP
LDO1 CURRENT LIMIT
LDO2 CURRENT LIMIT
BANDGAP
BANDGAP
LDO1
R11
R10
LDO2
R9
R12
1.25V
REFERENCE
CONTROL
LOGIC
REFBP
AGND
BANDGAP
EN1
EN2
PA_EN
PAB
IN1B
IN1A
Figure 1. Block Diagram
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
14 ______________________________________________________________________________________
Detailed Description
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z are
designed to dynamically power the PA in WCDMA and
NCDMA handsets. The devices contain a high-frequency,
high-efficiency step-down converter, and two LDOs.
The MAX8805Y/MAX8805Z step-down converters deliver
over 600mA, while the MAX8805W/MAX8805X deliver
over 650mA. The hysteretic PWM control scheme pro-
vides extremely fast transient response, while 2MHz and
4MHz switching-frequency options allow the trade-off
between efficiency and the smallest external compo-
nents. A 60mΩbypass FET connects the PA directly to
the battery during high-power transmission.
Step-Down Converter Control Scheme
A hysteretic PWM control scheme ensures high effi-
ciency, fast switching, fast transient response, low-out-
put ripple, and physically tiny external components.
The control scheme is simple: when the output voltage
is below the regulation threshold, the error comparator
begins a switching cycle by turning on the high-side
switch. This high-side switch remains on until the mini-
mum on-time expires and the output voltage is within
regulation, or the inductor current is above the current-
limit threshold. Once off, the high-side switch remains
off until the minimum off-time expires and the output
voltage falls again below the regulation threshold.
During the off period, the low-side synchronous rectifier
turns on and remains on until the high-side switch turns
on again. The internal synchronous rectifier eliminates
the need for an external Schottky diode.
Voltage-Positioning Load Regulation
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z step-
down converters utilize a unique feedback network. By
taking DC feedback from the LX node through R1 in
Figure 1, the usual phase lag due to the output capacitor
is removed, making the loop exceedingly stable and
allowing the use of very small ceramic output capacitors.
To improve the load regulation, resistor R3 is included in
the feedback. This configuration yields load regulation
equal to half of the inductor’s series resistance multiplied
by the load current. This voltage-positioning load regula-
tion greatly reduces overshoot during load transients or
when changing the output voltage from one level to anoth-
er. However, when calculating the required REFIN volt-
age, the load regulation should be considered. Because
inductor resistance is typically well specified and the
typical PA is a resistive load, the MAX8805Y/MAX8805Z
VREFIN to VOUT gain is slightly less than 2V/V, and the
MAX8805W/MAX8805X VREFIN to VOUT gain is slightly
less than 2.5V/V. The output voltage is aproximately:
VOUT = (REFIN to PA_Gain) x VREFIN - 1/2 x LESR x ILOAD
Step-Down Converter Bypass Mode
During high-power transmission, the bypass mode con-
nects IN1A and IN1B directly to PAA and PAB with the
internal 60mΩ(typ) bypass FET, while the step-down
converter is forced into 100% duty-cycle operation. The
low on-resistance in this mode provides low dropout,
long battery life, and high output current capability.
Forced and Automatic Bypass Mode
Invoke forced bypass mode by driving HP high or
invoke automatic bypass mode by applying a high volt-
age to REFIN. To prevent excessive output ripple as
the step-down converter approaches dropout, the
MAX8805Y/MAX8805Z enter bypass mode automatical-
ly when VREFIN > 0.465 x VIN2 (see Figure 2) and
MAX8805W/MAX8805X enter bypass mode automati-
cally when VREFIN > 0.372 x VIN2. Note that IN2 is used
instead of IN1 to prevent switching noise from causing
false enagement of automatic bypass mode. For this
reason, IN2 must be connected to the same source
as IN1.
Shutdown Mode
Connect PA_EN to GND or logic-low to place the
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z PA
step-down converter in shutdown mode. In shutdown,
the control circuitry, internal switching MOSFET, and
synchronous rectifier turn off and LX becomes high
impedance. Connect PA_EN to IN1_ or logic-high for
normal operation.
Connect EN1 or EN2 to GND or logic-low to place
LDO1 or LDO2, respectively, in shutdown mode. In
0
1.0
0.5
2.0
1.5
3.0
2.5
3.5
4.5
4.0
5.0
010152052530354540 50
TIME (ms)
IN2 AND PA_
VOLTAGE (V)
REFIN VOLTAGE (V)
IN2
PA_
REFIN
0
0.5
1.0
1.5
2.0
2.5
Figure 2. VIN2 and VPA_ with Automatic Entry/Exit into Bypass
Mode (MAX8805Y/MAX8805Z)
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
______________________________________________________________________________________ 15
shutdown, the outputs of the LDOs are pulled to ground
through an internal 1kΩresistor.
When the PA step-down and LDOs are all in shutdown,
the MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
enter a very low power state, where the input current
drops to 0.1µA (typ).
Step-Down Converter Soft-Start
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z PA
step-down converter has internal soft-start circuitry that
limits inrush current at startup, reducing transients on the
input source. Soft-start is particularly useful for supplies
with high output impedance such as Li+ and alkaline
cells. See the PA Step-Down Soft-Start Waveforms
(MAX8805X/MAX8805Z) and PA Step-Down Soft-Start
Waveforms (MAX8805W/MAX8805Y) in the
Typical
Operating Characteristics.
Analog REFIN Control
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z PA
step-down converter uses REFIN to set the output volt-
age. This allows the converter to operate in applications
where dynamic voltage control is required.
Thermal Shutdown
Thermal shutdown limits total power dissipation in the
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z. If the
junction temperature exceeds +160°C, thermal-shut-
down circuitry turns off the IC, allowing it to cool. The IC
turns on and begins soft-start after the junction temper-
ature cools by 20°C. This results in a pulsed output dur-
ing continuous thermal-overload conditions.
Applications Information
Output Voltages
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z PA
step-down converters set the PA_ output voltage based
on the voltage applied to REFIN.
LDO1 and LDO2 output voltages are determined by the
part number suffix, as shown in Table 1.
LDO Dropout Voltage
The regulator’s minimum input/output differential (or
dropout voltage) determines the lowest usable supply
voltage. In battery-powered systems, this determines
the useful end-of-life battery voltage. Because the
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z LDOs use
a p-channel MOSFET pass transistor, their dropout volt-
ages are a function of drain-to-source on-resistance
(RDS(ON)) multiplied by the load current (see the
Typical
Operating Characteristics
).
Inductor Selection
The MAX8805W/MAX8805Y operate with a switching
frequency of 2MHz and utilize a 2.2µH inductor. The
MAX8805X/MAX8805Z operate with a switching fre-
quency of 4MHz and utilize a 1µH inductor. The higher
switching frequency of the MAX8805X/MAX8805Z allow
the use of physically smaller inductors at the cost of
slightly lower efficiency. The lower switching frequency
of the MAX8805W/MAX8805Y results in greater efficien-
cy at the cost of a physically larger inductor. See the
Typical Operating Characteristics
for efficiency graphs
for both the MAX8805W/MAX8805Y and MAX8805X/
MAX8805Z.
The inductor’s DC current rating only needs to match the
maximum load of the application because the
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z feature
zero current overshoot during startup and load tran-
sients. For optimum transient response and high efficien-
cy, choose an inductor with DC series resistance in the
50mΩto 150mΩrange. See Table 2 for suggested
inductors and manufacturers.
Output Capacitor Selection
For the PA step-down converter, the output capacitor
(CPA) is required to keep the output voltage ripple small
and ensure regulation loop stability. CPA must have low
impedance at the switching frequency. Ceramic capaci-
tors with X5R or X7R dielectric are highly recommended
Table 1. LDO1 and LDO2 Output Voltage
Selection
Note: Contact the factory for other output-voltage options.
PART
FREQUENCY
(MHz)
LDO1
(V)
LDO2
(V)
MAX8805WEWEAA+T
2 1.80 1.80
MAX8805WEWEAE+T
2 1.80 2.85
MAX8805WEWEEE+T
2 2.85 2.85
MAX8805XEWEAA+T
4 1.80 1.80
MAX8805XEWEAE+T
4 1.80 2.85
MAX8805XEWEEE+T
4 2.85 2.85
MAX8805YEWEAA+T
2 1.80 1.80
MAX8805YEWEAE+T
2 1.80 2.85
MAX8805YEWEEE+T
2 2.85 2.85
MAX8805ZEWEAA+T
4 1.80 1.80
MAX8805ZEWEAE+T
4 1.80 2.85
MAX8805ZEWEEE+T
4 2.85 2.85
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
16 ______________________________________________________________________________________
due to their small size, low ESR, and small temperature
coefficients. Due to the unique feedback network, the
output capacitance can be very low. A 2.2µF capacitor
is recommended for most applications. For optimum
load-transient performance and very low output ripple,
the output capacitor value can be increased.
For LDO1 and LDO2, the minimum output capacitance
required is dependent on the load currents. For loads
less than 10mA, it is sufficient to use a 0.1µF capacitor
for stable operation over the full temperature range.
With rated maximum load currents, a minimum of 1µF is
recommended. Reduce output noise and improve load-
transient response, stability, and power-supply rejec-
tion by using larger output capacitors.
Note that some ceramic dielectrics exhibit large capaci-
tance and ESR variation with temperature. With dielectrics
such as Z5U and Y5V, it is necessary to use 2.2µF or larg-
er to ensure stability at temperatures below -10°C. With
X7R or X5R dielectrics, 1µF is sufficient at all operating
temperatures. These regulators are optimized for ceramic
capacitors. Tantalum capacitors are not recommended.
Input Capacitor Selection
The input capacitor (CIN1) of the PA converter reduces
the current peaks drawn from the battery or input
power source and reduces switching noise in the
Table 2. Suggested Inductors
MANUFACTURER
SERIES INDUCTANCE
(µH)
ESR
(Ω)
CURRENT RATING
(mA)
DIMENSIONS
(mm)
Coilcraft LPO3310
1.0
1.5
2.2
0.07
0.10
0.13
1600
1400
1100
3.3 x 3.3 x 1.0 = 11mm3
MIPF2520
1.0
1.5
2.2
0.05
0.07
0.08
1500
1500
1300
2.5 x 2.0 x 1.0 = 5mm3
MIPS2520 1.3
2.0
0.09
0.11
1500
1200
2.5 x 2.0 x 1.0 = 5mm3
FDK
MIPF2016 1.0
2.2 0.11 1100
2.0 x 1.6 x 1.0 = 3.2mm3
Hitachi
KSLI-252010
1.5
2.2
0.115
0.080 —
2.5 x 2.0 x 1.0 = 5mm3
Murata LQH32C_53 1.0
2.2
0.06
0.10
1000
790
3.2 x 2.5 x 1.7 = 14mm3
Sumida CDRH2D09
1.2
1.5
2.2
0.08
0.09
0.12
590
520
440
3.0 x 3.0 x 1.0 = 9mm3
CDRH2D11
1.5
2.2
3.3
0.05
0.08
0.10
680
580
450
3.2 x 3.2 x 1.2 = 12mm3
Taiyo Yuden
CB2518T 2.2
4.7
0.09
0.13
510
340
2.5 x 1.8 x 2.0 = 9mm3
D3010FB 1.0 0.20 1170
3.0 x 3.0 x 1.0 = 9mm3
D2812C 1.2
2.2
0.09
0.15
860
640
3.0 x 3.0 x 1.2 = 11mm3
D310F 1.5
2.2
0.13
0.17
1230
1080
3.6 x 3.6 x 1.0 = 13mm3
TOKO
D312C 1.5
2.2
0.10
0.12
1290
1140
3.6 x 3.6 x 1.2 = 16mm3
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
______________________________________________________________________________________ 17
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z. The
impedance of CIN1 at the switching frequency should
be kept very low. Ceramic capacitors with X5R or X7R
dielectric are highly recommended due to their small
size, low ESR, and small temperature coefficients. A
2.2µF capacitor is recommended for most applications.
For optimum noise immunity and low input ripple, the
input capacitor value can be increased.
For the LDOs, use an input capacitance equal to the
value of the sum of the output capacitance of LDO1 and
LDO2. Larger input capacitor values and lower ESR pro-
vide better noise rejection and line transient response.
Note that some ceramic dielectrics exhibit large capaci-
tance and ESR variation with temperature. With
dielectrics such as Z5U and Y5V, it may be necessary to
use two times the sum of the output capacitor values of
LDO1 and LDO2 (or larger) to ensure stability at temper-
atures below -10°C. With X7R or X5R dielectrics, a
capacitance equal to the sum is sufficient at all operating
temperatures.
Thermal Considerations
In most applications, the MAX8805W/MAX8805X/
MAX8805Y/MAX8805Z do not dissipate much heat due
to their high efficiency. However, in applications where
the MAX8805W/MAX8805X/MAX8805Y/MAX8805Z run
at high ambient temperature with heavy loads, the heat
dissipated may exceed the maximum junction tempera-
ture of the IC. If the junction temperature reaches
approximately +160°C, all power switches are turned
off and LX and PA_ become high impedance, and
LDO1 and LDO2 are pulled down to ground through an
internal 1kΩpulldown resistor.
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
maximum power dissipation depends on the thermal
resistance of the IC package and circuit board, the
temperature difference between the die junction and
ambient air, and the rate of airflow. The power dissipat-
ed in the device is:
PDISS = PPA x (1/ηPA - 1) + ILDO1 x (VIN2 - VLDO1) +
ILDO2 x (VIN2 - VLDO2)
where ηPA is the efficiency of the PA step-down con-
verter and PPA is the output power of the PA step-down
converter.
The maximum allowed power dissipation is:
PMAX = (TJMAX - TA) / θJA
where (TJMAX - TA) is the temperature difference
between the MAX8805W/MAX8805X/MAX8805Y/
MAX8805Z die junction and the surrounding air; θJA is
the thermal resistance of the junction through the PCB,
copper traces, and other materials to the surrounding air.
PCB Layout
High switching frequencies and relatively large peak
currents make the PCB layout a very important part of
design. Good design minimizes excessive EMI on the
feedback paths and voltage gradients in the ground
plane, resulting in a stable and well-regulated output.
Connect CIN1 close to IN1A/IN1B and PGND. Connect
the inductor and output capacitor as close as possible
to the IC and keep their traces short, direct, and wide.
Keep noisy traces, such as the LX node, as short as
possible. Figure 3 illustrates an example PCB layout
and routing scheme.
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
18 ______________________________________________________________________________________
REFIN
VIN
PA_EN
EN1
LDO1
LDO2
HP
5.5mm
EN2
AGND PGND
3.8mm
CIN2
CPA
CBYP
CLDO2
CLDO1
VPA LPA
CIN1
Figure 3. Recommended PCB Layout
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
______________________________________________________________________________________ 19
2.2μF
2MHz OR 4MHz
BUCK
1μH OR
2.2μH*
LX
PBB
PGND
PBA
IN1A
IN1B
EN2
REFIN
2.2μF
REF 0.22μF
REFBP
AGND
LDO1
0.1μF
0.1μF
LDO2
IN2
1μF
PA_EN
HP
EN1 CONTROL
EN/BIAS
IN
PA2
EN/BIAS
IN
PA1
GPIO
GPIO
GPIO
GPIO
DAC
BASEBAND
PROCESSOR
Li+ BATTERY
LDO1
LDO2
MAX8805W
MAX8805X
MAX8805Y
MAX8805Z
*1μH FDK MIPS 2520D1R0
2.2μH FDK MIPF 2520D2R2
Figure 4. Typical Application Circuit Using LDOs for PA Enable/Bias
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
20 ______________________________________________________________________________________
2.2μF
2MHz OR 4MHz
BUCK
1μH OR
2.2μH*
LX
PBB
PGND
PBA
IN1A
IN1B
EN2
REFIN
2.2μF
REF 0.22μF
REFBP
AGND
LDO1
1μF
1μF
LDO2
IN2
2.2μF
PA_EN
HP
EN1 CONTROL
RF TRANSMITTER
IN
IN
PA
GPIO
GPIO
GPIO
GPIO
DAC
BASEBAND
PROCESSOR
Li+ BATTERY
LDO1
LDO2
RF RECEIVER
IN
*1μH FDK MIPS 2520D1R0
2.2μH FDK MIPF 2520D2R2
MAX8805W
MAX8805X
MAX8805Y
MAX8805Z
Figure 5. Typical Application Circuit Using LDOs for RF Power
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
______________________________________________________________________________________ 21
REFBP AGND
LDO2
IN2
REFIN
EN2
IN1B
PA_EN
(BUMP IN BOTTOM)
16-Bump, 2mm × 2mm WLP
HP
LDO1 PABEN1
PGND
LX
IN1A
PAA
A1 A2 A3 A4
B1 B4
B3
B2
C1 C2 C3 C4
D1 D4
D3
D2
TOP VIEW
Pin Configuration
Chip Information
PROCESS: BiCMOS
IN1A
LX
PAA
1μH
BATT
2.7V TO 5.5V
AGND
PA_EN
REFIN
EN1
EN2
IN2
BATT
2.7V TO 5.5V
PA ON/OFF
ANALOG CONTROL
VPA
0.4V TO VBATT
REFBP
IN1B
LDO1 ON/OFF
LDO2 ON/OFF
PAB
LDO2
LDO1
VLDO2 UP
TO 200mA
PGND
HP
FORCED BYPASS
2.2μF
2.2μF
MAX8805X
MAX8805Z
VLDO1 UP
TO 200mA
Typical Operating Circuit
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
22 ______________________________________________________________________________________
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
16 WLP W162B2+1 21-0200
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
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 ____________________
23
© 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
2 3/08 Updating package information 21
3 5/08 Corrected maximum range of Y axis for TOC 03 5
4 9/08 Updated EC table, TOC 13, and Voltage-Positioning Load Regulation section 1, 2, 3, 6, 14