Maxim MAX8805YEWEAA+T 600ma/650ma pwm step-down converters in 2mm x 2mm wlp for wcdma pa power Datasheet

19-0777; Rev 1; 10/07
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
Features
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 mediumand low-power transmission, and a 60mΩ typical
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 biasing 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.
♦ PA 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
60mΩ pFET 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% Maximum Accuracy
Tiny External Components
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 automatically 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
(35µV RMS 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).
♦ Dual Low-Noise LDOs
Low 35µVRMS (typ) Output Noise
High 70dB (typ) PSRR
Guaranteed 200mA Output Drive Capability
Individual ON/OFF Control
♦ Low 0.1µA Shutdown Current
♦ 2.7V to 5.5V Supply Voltage Range
♦ Thermal Shutdown
♦ Tiny 2mm x 2mm x 0.7mm WLP Package
(4 x 4 Grid)
Applications
WCDMA/NCDMA Cellular Handsets
Wireless PDAs
Smartphones
Pin Configuration appears at end of data sheet.
Ordering Information
PINPACKAGE
PKG
CODE
SWITCHING
FREQUENCY
REFIN TO OUT GAIN
MAX8805WEWExy+T*
16 WLP-16
W162B2+1
2MHz
2.5V/V
MAX8805XEWExy+T*
16 WLP-16
W162B2+1
4MHz
2.5V/V
MAX8805YEWExy+T*
16 WLP-16
W162B2+1
2MHz
2V/V
MAX8805ZEWExy+T*
16 WLP-16
W162B2+1
4MHz
2V/V
PART
+Denotes a lead-free package.
T = Tape and reel package.
*xy is the output voltage code (see Table 1).
Note: All devices are specified over the -40°C to +85°C operating temperature range.
________________________________________________________________ Maxim Integrated Products
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.
1
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
General Description
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
ABSOLUTE MAXIMUM RATINGS
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
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 recommended 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.
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
(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
5.5
V
2.63
2.70
V
TA = +25°C
0.1
4
TA = +85°C
0.1
INPUT SUPPLY
Input Voltage
VIN1A, VIN1B, VIN2
2.7
Input Undervoltage Threshold
VIN1A, VIN1B, VIN2 rising, 180mV typical hysteresis
2.52
Shutdown Supply Current
VPA_EN = VEN1 = VEN2 = 0V
VPA_EN = 0V, ILDO1 = ILDO2 = 0mA
No-Load Supply Current
VEN1 = VEN2 = 0V, IPA = 0mA,
switching
150
MAX8805W/MAX8805Y
3500
MAX8805X/MAX8805Z
5000
VEN1 = VEN2 = 0V, VHP = 3.6V
µA
250
µA
150
THERMAL PROTECTION
Thermal Shutdown
TA rising, 20°C typical hysteresis
°C
+160
LOGIC CONTROL
PA_EN, EN1, EN2, HP LogicInput High Voltage
2.7V ≤ VIN1A = VIN1B = VIN2 ≤ 5.5V
PA_EN, EN1, EN2, HP LogicInput Low Voltage
2.7V ≤ VIN1A = VIN1B = VIN2 ≤ 5.5V
Logic-Input Current
(PA_EN, EN1, EN2, HP)
VIL = 0V or VIH = VIN1A = 5.5V
1.4
V
0.4
TA = +25°C
0.01
TA = +85°C
0.1
1
V
µA
REFIN
REFIN Common-Mode Range
REFIN to PA_ Gain (Falling Edge)
REFIN Input Resistance
2
MAX8805Y/MAX8805Z
0.1
2.2
MAX8805W/MAX8805X
VREFIN = 0.4V, 0.9V, 1.7V,
2.2V
0.1
1.7
VREFIN = 0.32V, 0.75V,
1.32V, 1.76V
MAX8805Y/MAX8805Z
1.96
2.00
2.04
MAX8805W/MAX8805X
2.45
2.50
2.55
V
V/V
MAX8805Y/MAX8805Z
540
MAX8805W/MAX8805X
320
_______________________________________________________________________________________
kΩ
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
(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
REFIN
Dual Mode™ Threshold
CONDITIONS
MIN
TYP
MAX
MAX8805Y/MAX8805Z
0.44 x
VIN2
0.465 x
VIN2
0.48 x
VIN2
MAX8805W/MAX8805X
0.36 x
VIN2
0.372 x
VIN2
0.39 x
VIN2
p-channel MOSFET switch, ILX = -40mA
0.18
0.6
n-channel MOSFET rectifier, ILX = 40mA
0.15
0.6
TA = +25°C
0.1
5
TA = +85°C
1
VREFIN rising, 50mV hysteresis
UNITS
V
LX
On-Resistance
LX Leakage Current
VIN1A = VIN1B = VIN2 = 5.5V,
VLX = 0V
p-Channel MOSFET Peak
Current Limit
VLX = 0V
n-Channel MOSFET Valley
Current Limit
Minimum On- and Off-Times
Power-Up Delay
MAX8805Y/MAX8805Z
0.7
0.9
1.1
MAX8805W/MAX8805X
0.75
0.95
1.15
MAX8805Y/MAX8805Z
0.5
0.7
0.9
MAX8805W/MAX8805X
0.55
0.75
0.95
MAX8805Y/MAX8805Z
0.1
MAX8805W/MAX8805X
0.07
From PA_EN rising to LX rising
150
250
TA = +25°C
0.060
0.1
TA = +85°C
0.1
Ω
µA
A
A
µs
µs
BYPASS
On-Resistance
p-channel MOSFET bypass,
IOUT = -90mA
Bypass Current Limit
VPA = 0V
Step-Down Current Limit in Bypass VLX = 0V
Total Bypass Current Limit
VLX = VPA = 0V
Bypass Off-Leakage Current
VIN1A = VIN1B = VIN2 = 5.5V,
VPAA = VPAB = 0V
0.8
1.2
1.8
MAX8805Y/MAX8805Z
0.7
0.9
1.1
MAX8805W/MAX8805X
0.75
0.95
1.15
MAX8805Y/MAX8805Z
1.5
2.1
2.9
MAX8805W/MAX8805X
1.55
2.15
2.95
TA = +25°C
0.01
10
TA = +85°C
1
Ω
A
A
A
µA
LDO1
Output Voltage VLDO1
VIN2 = 5.5V, ILDO1 = 1mA;
VIN2 = 3.4V, ILDO1 = 100mA
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
MAX8805_EWEGG+T
2.910
3.0
3.090
550
750
200
Output Current
200
250
V
mA
Current Limit
VLDO1 = 0V
mA
Dropout Voltage
ILDO1 = 100mA, TA = +25°C (VLDO1 ≥ 2.5V)
70
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
mV
_______________________________________________________________________________________
3
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
ELECTRICAL CHARACTERISTICS (continued)
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
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
Output Capacitor for Stable
Operation
0 < ILDO1 < 10mA
100
nF
0 < ILDO1 < 200mA
1
µF
Shutdown Output Impedance
VEN1 = 0V
1
kΩ
LDO2
Output Voltage VLDO2
VIN2 = 5.5V, ILDO2 = 1mA;
VIN2 = 3.4V, ILDO2 = 100mA
MAX8805_EWEAA+T
1.746
1.8
1.854
MAX8805_EWEAC+T
2.619
2.7
2.781
V
MAX8805_EWEAD+T
2.716
2.8
2.884
MAX8805_EWEBE+T
2.765
2.85
2.936
MAX8805_EWEGG+T
2.910
3.0
3.090
550
750
mA
200
mV
Output Current
200
250
mA
Current Limit
VLDO2 = 0V
Dropout Voltage
ILDO2 = 100mA, TA = +25°C
70
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
Output Capacitor for Stable
Operation
0µA < ILDO2 < 10mA
100
nF
0µA < ILDO2 < 200mA
1
µF
Shutdown Output Impedance
VEN2 = 0V
1
kΩ
REFBP
REFBP Output Voltage
0 ≤ IREFBP ≤ 1µA
REFBP Supply Rejection
VIN2 stepped from 2.55V to 5.5V
1.237
1.250
1.263
V
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.
4
_______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
80
VIN1 = 3.6V
60
90
40
BYPASS MODE
VIN1 = 4.2V
80
90
EFFICIENCY (%)
VIN1 = 3.2V
100
EFFICIENCY (%)
120
200
MAX8805W/X/Y/Z toc02
100
MAX8805W/X/Y/Z toc01
BYPASS MODE DROPOUT VOLTAGE (mV)
140
PA STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT VOLTAGE (MAX8805W/MAX8805X)
PA STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT VOLTAGE (MAX8805X/MAX8805Z)
VIN1 = 3.6V
VIN1 = 3.2V
BYPASS MODE
VIN1 = 4.2V
VIN1 = 3.6V
80
VIN1 = 3.2V
70
70
20
RPA = 7.5Ω
RPA = 7.5Ω
60
60
0
0.5
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
1.0
1.5
2.0
2.5
3.0
3.5
4.0
PA STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT VOLTAGE (MAX8805W/MAX8805Y)
90
VIN1 = 3.6V
VIN1 = 3.2V
BYPASS MODE
VIN1 = 4.2V
VIN1 = 3.6V
80
2.0
2.5
3.0
3.5
4.0
100
VPA = 1.8V
90
EFFICIENCY (%)
EFFICIENCY (%)
VIN1 = 4.2V
80
100
MAX8805W/X/Y/Z toc04
BYPASS MODE
1.5
4.5
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805X/MAX8805Z)
MAX8805W/X/Y/Z toc05
PA STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT VOLTAGE (MAX8805X/MAX8805Z)
90
1.0
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
100
0.5
4.5
PA LOAD CURRENT (A)
VIN1 = 3.2V
MAX8805W/X/Y/Z toc06
0
EFFICIENCY (%)
MAX8805W/X/Y/Z toc03
BYPASS MODE DROPOUT VOLTAGE
vs. PA LOAD CURRENT
80
VIN1 = 3.2V
VIN1 = 3.6V
VIN1 = 4.2V
70
70
70
60
RPA = 10Ω
RPA = 10Ω
60
60
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
1.0
1.5
2.0
2.5
3.0
3.5
4.0
50
4.5
0
100
200
300
400
500
600
700
OUTPUT VOLTAGE (V)
LOAD CURRENT (mA)
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805W/MAX8805Y)
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805X/MAX8805Z)
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805W/MAX8805Y)
VIN1 = 4.2V
VIN1 = 3.6V
70
60
MAX8805W/X/Y/Z toc08
90
80
VIN1 = 4.2V
70
VIN1 = 3.2V
VIN1 = 3.6V
100
200
300
400
500
LOAD CURRENT (mA)
600
700
90
80
VIN1 = 4.2V
VIN1 = 3.2V
70
VIN1 = 3.6V
50
50
0
VPA = 1.2V
60
60
50
100
EFFICIENCY (%)
VIN1 = 3.2V
VPA = 1.2V
EFFICIENCY (%)
90
80
100
MAX8805W/X/Y/Z toc07
VPA = 1.8V
MAX8805W/X/Y/Z toc09
OUTPUT VOLTAGE (V)
100
EFFICIENCY (%)
0.5
4.5
0
100
200
300
400
500
LOAD CURRENT (mA)
600
700
0
100
200
300
400
500
600
700
LOAD CURRENT (mA)
_______________________________________________________________________________________
5
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
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 otherwise noted.)
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 otherwise noted.)
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805X/MAX8805Z)
100
80
70
VPA = 0.6V
90
EFFICIENCY (%)
90
VIN1 = 4.2V
VIN1 = 4.2V
70
VIN1 = 3.2V
VIN1 = 3.6V
60
VIN1 = 3.6V
50
50
100
200
300
400
500
600
700
0
100
200
300
400
500
600
700
LOAD CURRENT (mA)
LOAD CURRENT (mA)
PA STEP-DOWN CONVERTER OUTPUT
VOLTAGE vs. LOAD CURRENT
PA STEP-DOWN CONVERTER OUTPUT
VOLTAGE vs. REFIN VOLTAGE
MAX8805X/MAX8805Z
1.15
MAX8805W/MAX8805Y
MAX8805Y/Z toc13
1.20
4.0
3.5
OUTPUT VOLTAGE (V)
1.25
MAX8805W/X/Y/Z toc12
0
OUTPUT VOLTAGE (V)
80
VIN1 = 3.2V
60
MAX8805W/X/Y/Z toc11
VPA = 0.6V
EFFICIENCY (%)
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805W/MAX8805Y)
MAX8805W/X/Y/Z toc10
100
1.10
3.0
2.5
2.0
1.5
1.0
1.05
0.5
100
200
300
400
500
600
700
0
LOAD CURRENT (mA)
40
1.2
1.6
2.0
REFIN vs. REFIN TO OUT GAIN (MAX8805Y)
VIN1 = 4.2V, NO LOAD
20
0
-20
-40
-60
50
OUTPUT VOLTAGE ERROR (mV)
VIN1 = 3.2V, NO LOAD
60
MAX8805Y/Z toc14
80
0.8
REFIN VOLTAGE (V)
REFIN vs. REFIN TO OUT GAIN (MAX8805Z)
100
0.4
VIN1 = 3.2V, NO LOAD
30
VIN1 = 4.2V, NO LOAD
MAX8805Y/Z toc15
0
OUTPUT VOLTAGE ERROR (mV)
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
10
-10
-30
-80
-50
-100
6
0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5
0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5
REFIN VOLTAGE (V)
REFIN VOLTAGE (V)
_______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
VIN1 = 4.2V, NO LOAD
10
-10
-30
OUTPUT VOLTAGE ERROR (mV)
VIN1 = 3.2V, NO LOAD
MAX8805W/X/Y/Z toc16
OUTPUT VOLTAGE ERROR (mV)
30
50
VIN1 = 3.2V, NO LOAD
30
VIN1 = 4.2V, NO LOAD
MAX8805W/X/Y/Z toc17
REFIN vs. REFIN TO OUT GAIN (MAX8805W)
REFIN vs. REFIN TO OUT GAIN (MAX8805X)
50
10
-10
-30
-50
-50
0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3
0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3
REFIN VOLTAGE (V)
REFIN VOLTAGE (V)
PA STEP-DOWN CONVERTER LIGHT-LOAD
SWITCHING WAVEFORMS (MAX8805X/MAX8805Z)
PA STEP-DOWN CONVERTER LIGHT-LOAD
SWITCHING WAVEFORMS (MAX8805W/MAX8805Y)
MAX8805W/X/Y/Z toc19
MAX8805W/X/Y/Z toc18
VPA
AC-COUPLED
20mV/div
VPA
AC-COUPLED
20mV/div
ILX
200mA/div
ILX
200mA/div
VLX
2V/div
VLX
2V/div
VPA = 1.2V, IPA = 50mA
VPA = 1.2V, IPA = 50mA
400ns/div
400ns/div
PA STEP-DOWN HEAVY-LOAD
SWITCHING WAVEFORMS (MAX8805X/MAX8805Z)
PA STEP-DOWN HEAVY-LOAD
SWITCHING WAVEFORMS (MAX8805W/MAX8805Y)
MAX8805W/X/Y/Z toc20
VPA
AC-COUPLED
MAX8805W/X/Y/Z toc21
20mV/div
VPA
AC-COUPLED
20mV/div
ILX
500mA/div
ILX
500mA/div
VLX
2V/div
VLX
2V/div
VPA = 1.2V, IPA = 500mA
400ns/div
VPA = 1.2V, IPA = 500mA
400ns/div
_______________________________________________________________________________________
7
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
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 otherwise noted.)
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
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 otherwise noted.)
PA STEP-DOWN SOFT-START
WAVEFORMS (MAX8805W/MAX8805Y)
PA STEP-DOWN SOFT-START
WAVEFORMS (MAX8805X/MAX8805Z)
MAX8805W/X/Y/Z toc23
MAX8805W/X/Y/Z toc22
VPA_EN
2V/div
VPA_EN
2V/div
VPA
1V/div
VPA
1V/div
ILX
500mA/div
ILX
200mA/div
20μs/div
20μs/div
PA STEP-DOWN CONVERTER LINE
TRANSIENT RESPONSE (MAX8805X/MAX8805Z)
PA STEP-DOWN CONVERTER LINE
TRANSIENT RESPONSE (MAX8805W/MAX8805Y)
MAX8805W/X/Y/Z toc24
VIN1
MAX8805W/X/Y/Z toc25
4.0V
4.0V
500mV/div
3.5V
VPA
AC-COUPLED
50mV/div
ILX
4.0V
4.0V
200mA/div
VIN1
VPA
AC-COUPLED
50mV/div
ILX
200mA/div
10μs/div
10μs/div
PA STEP-DOWN CONVERTER LOAD
TRANSIENT RESPONSE (MAX8805X/MAX8805Z)
PA STEP-DOWN CONVERTER LOAD
TRANSIENT RESPONSE (MAX8805W/MAX8805Y)
MAX8805W/X/Y/Z toc27
MAX8805W/X/Y/Z toc26
500mA
500mA
500mA/div
IPA
ILX
500mA/div
ILX
500mA/div
VPA
AC-COUPLED
100mV/div
VPA
AC-COUPLED
100mV/div
IPA
0mA
0mA
10μs/div
8
500mV/div
3.5V
0mA
0mA
10μs/div
_______________________________________________________________________________________
500mA/div
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
MAX8805W/X/Y/Z toc28
MAX8805W/X/Y/Z toc29
1.5V
VREFIN
500mV/div
VHP
500mV/div
VPA
0V
1V
VPA
2V/div
0V
3.6V
0.5V
0.5V
500mA/div
ILX
2V/div
1.2V
1.2V
500mA/div
ILX
10μs/div
20μs/div
PA STEP-DOWN CONVERTER OUTPUT
VOLTAGE TRANSIENT RESPONSE
(MAX8805W/MAX8805X)
PA STEP-DOWN CONVERTER
BYPASS-FET TRANSIENT RESPONSE
(MAX8805W/MAX8805X)
MAX8805W/X/Y/Z toc31
MAX8805W/X/Y/Z toc30
2V
VREFIN
500mV/div
VHP
500mV/div
VPA
1.25V
VPA
3.6V
0.66V
0.66V
2V/div
0V
0V
ILX
500mA/div
1.2V
1.2V
2V/div
ILX
500mA/div
10μs/div
20μs/div
PA STEP-DOWN CONVERTER AUTOMATIC
BYPASS-FET TRANSIENT RESPONSE
(MAX8805Y/MAX8805Z)
PA STEP-DOWN CONVERTER AUTOMATIC
BYPASS-FET TRANSIENT RESPONSE
(MAX8805Y/MAX8805Z)
MAX8805W/X/Y/Z toc32
MAX8805W/X/Y/Z toc33
1.8V
VREFIN
1V/div
VREFIN IS A 0.4V TO
2V SINUSOIDAL
VREFIN SIGNAL
0.6V
0.6V
1V/div
3.6V
3.6V
2V/div
VPA 1.2V
1.2V
1V/div
VPA
500mA/div
ILX
ILX
10μs/div
500mA/div
200μs/div
_______________________________________________________________________________________
9
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
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 otherwise noted.)
PA STEP-DOWN CONVERTER OUTPUT
PA STEP-DOWN CONVERTER FORCED
VOLTAGE TRANSIENT RESPONSE
BYPASS-FET TRANSIENT RESPONSE
(MAX8805Y/MAX8805Z)
(MAX8805Y/MAX8805Z)
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 otherwise noted.)
PA STEP-DOWN CONVERTER
AUTOMATIC BYPASS-FET TRANSIENT
RESPONSE (MAX8805W/MAX8805X)
PA STEP-DOWN CONVERTER
BYPASS-FET TRANSIENT RESPONSE
(MAX8805W/MAX8805X)
MAX8805W/X/Y/Z toc35
MAX8805W/X/Y/Z toc34
1.44V
VREFIN
1V/div
0.48V
0.48V
1V/div
VREFIN
2V/div
VPA
3.6V
3.6V
VPA
1.2V
1.2V
500mA/div
ILX
1V/div
VREFIN IS A 0.48V TO
2.1V SINSOIDAL
SIGNAL
500mA/div
ILX
10μs/div
200μs/div
PA STEP-DOWN CONVERTER SHUTDOWN
RESPONSE (MAX8805W/MAX8805Y)
PA STEP-DOWN CONVERTER SHUTDOWN
RESPONSE (MAX8805X/MAX8805Z)
MAX8805W/X/Y/Z toc37
MAX8805W/X/Y/Z toc36
2V
2V
VPA_EN
2V/div
0V
VPA_EN
2V/div
0V
1.2V
1.2V
VPA
2V/div
1V/div
VPA
ILX
ILX
100mA/div
100mA/div
10μs/div
10μs/div
LDO1, LDO2 SUPPLY CURRENT
vs. SUPPLY VOLTAGE
LDO1, LDO2 DROPOUT VOLTAGE
vs. LOAD CURRENT
100
50
0
120
90
60
30
0
2.0
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
10
MAX8805W/X/Y/Z toc39
150
150
LDO1, LDO2 DROPOUT VOLTAGE (mV)
MAX8805W/X/Y/Z toc38
200
NO-LOAD SUPPLY CURRENT (μA)
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
5.0
5.5
0
50
100
150
LOAD CURRENT (mA)
______________________________________________________________________________________
200
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
LDO OUTPUT NOISE SPECTRAL DENSITY
vs. FREQUENCY
LDO PSRR vs. FREQUENCY
50
40
30
20
ILDO = 30mA
10
MAX8805W/X/Y/Z toc41
60
OUTPUT NOISE DENSITY NOISE (nV/√Hz)
70
PSRR (dB)
1.0E+04
MAX8805W/X/Y/Z toc40
80
1.0E+03
1.0E+02
1.0E+01
0.01
0.1
1
10
100
1000
0.01
0.1
FREQUENCY (kHz)
1
10
100
1000
FREQUENCY (kHz)
LDO1, LDO2 OUTPUT NOISE WAVEFORM
LDO LINE TRANSIENT RESPONSE
MAX8805W/X/Y/Z toc42
MAX8805W/X/Y/Z toc43
VIN2
4.0V
4.0V
500mV/div
3.5V
50mV/div
VLDO_
5mV/div
ILDO_ = 80mA
400μs/div
20μs/div
LDO1, LDO2 LOAD TRANSIENT
RESPONSE NEAR DROPOUT
LDO1, LDO2 TURN ON AND
SHUTDOWN RESPONSE
MAX8805W/X/Y/Z toc45
MAX8805W/X/Y/Z toc44
80mA
ILDO1
0mA
0mA
VLDO1
100mA/div
50mV/div
VEN1,2
2V/div
VLDO1
2V/div
VLDO2
2V/div
80mA
ILDO2
0mA
0mA
100mA/div
50mV/div
VLDO2
VIN2 = VLDO1,2 + 200mV
20μs/div
1ms/div
______________________________________________________________________________________
11
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
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 otherwise noted.)
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
Pin Description
PIN
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
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
D3, D4
12
NAME
LDO2 Enable Input. Connect to IN2 or logic-high for normal operation. Connect to AGND or logic-low for
shutdown mode.
LDO1 Enable Input. Connect to IN2 or logic-high for normal operation. Connect to AGND or logic-low for
shutdown mode.
PA Connection for Bypass Mode. Internally connected to IN1_ using the internal bypass MOSFET during
PAB, PAA 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.
______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
IN1A
IN1B
R4
BYPASS FET
R5
PAA
C1
R3
PAB
CURRENT-LIMIT CONTROL
HP
PWM ERROR
COMPARATOR
R7
REFIN
LX
PWM LOGIC
R6
C2
PGND
STEP-DOWN CURRENT LIMIT
R2
R1
IN2
BANDGAP
REFBP
1.25V
REFERENCE
AGND
LDO1 CURRENT LIMIT
LDO1
ERROR AMP
BANDGAP
R9
EN1
CONTROL
LOGIC
EN2
R8
PA_EN
R7
BANDGAP
LDO2 CURRENT LIMIT
LDO2
ERROR AMP
R12
R11
R10
Figure 1. Block Diagram
______________________________________________________________________________________
13
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 provides extremely fast transient response, while 2MHz and
4MHz switching-frequency options allow the trade-off
between efficiency and the smallest external components. A 60mΩ bypass FET connects the PA directly to
the battery during high-power transmission.
Step-Down Converter Control Scheme
A hysteretic PWM control scheme ensures high efficiency, fast switching, fast transient response, low-output 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 minimum on-time expires and the output voltage is within
regulation, or the inductor current is above the currentlimit 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.
Step-Down Converter Bypass Mode
During high-power transmission, the bypass mode connects 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 voltage to REFIN. To prevent excessive output ripple as
the step-down converter approaches dropout, the
MAX8805Y/MAX8805Z enter bypass mode automatically when V REFIN > 0.465 x V IN2 (see Figure 2) and
MAX8805W/MAX8805X enter bypass mode automatically 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.
4.5
2.0
4.0
3.5
1.5
3.0
2.5
1.0
2.0
Voltage-Positioning Load Regulation
1.5
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 regulation greatly reduces overshoot during
load transients or when changing the output voltage
from one level to another. However, when calculating
the required REFIN voltage, 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.
1.0
14
2.5
5.0
0.5
IN2
PA_
REFIN
0.5
REFIN VOLTAGE (V)
Detailed Description
IN2 AND PA_
VOLTAGE (V)
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
0
0
0
5
10 15 20 25 30 35 40 45 50
TIME (ms)
Figure 2. VIN2 and VPA_ with Automatic Entry/Exit into Bypass
Mode (MAX8805Y/MAX8805Z)
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
______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
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).
Table 1. LDO1 and LDO2 Output Voltage
Selection
PART
FREQUENCY
(MHz)
LDO1
(V)
LDO2
(V)
MAX8805WEWEAA+T
2
1.80
1.80
Step-Down Converter Soft-Start
MAX8805WEWEAE+T
2
1.80
2.85
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 Soft-Start Waveforms in the Typical
Operating Characteristics.
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
Analog REFIN Control
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z PA
step-down converter uses REFIN to set the output voltage. This allows the converter to operate in applications
where dynamic voltage control is required.
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
Note: Contact the factory for other output-voltage options.
Thermal Shutdown
Thermal shutdown limits total power dissipation in the
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z. If the
junction temperature exceeds +160°C, thermal-shutdown circuitry turns off the IC, allowing it to cool. The IC
turns on and begins soft-start after the junction temperature cools by 20°C. This results in a pulsed output during 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 voltages 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 frequency 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 efficiency 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 transients. For optimum transient response and high efficiency, choose an inductor with DC series resistance in the
50mΩ to 150mΩ range. 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 capacitors with X5R or X7R dielectric are highly recommended
______________________________________________________________________________________
15
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
shutdown, the outputs of the LDOs are pulled to ground
through an internal 1kΩ resistor.
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
Table 2. Suggested Inductors
SERIES
INDUCTANCE
(µH)
ESR
(Ω)
CURRENT RATING
(mA)
DIMENSIONS
(mm)
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
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
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
D312C
1.5
2.2
0.10
0.12
1290
1140
3.6 x 3.6 x 1.2 = 16mm3
MANUFACTURER
Coilcraft
FDK
Taiyo Yuden
TOKO
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-
16
transient response, stability, and power-supply rejection by using larger output capacitors.
Note that some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. With dielectrics
such as Z5U and Y5V, it is necessary to use 2.2µF or larger 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
______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
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 provide better noise rejection and line transient response.
Note that some ceramic dielectrics exhibit large capacitance 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 temperatures 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 temperature 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 1kΩ pulldown 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 dissipated 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 converter and PPA is the output power of the PA step-down
converter.
The maximum allowed power dissipation is:
PMAX = (TJMAX - TA) / θJA
where (T JMAX - T A ) 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.
______________________________________________________________________________________
17
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
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.
EN2
REFIN
HP
PA_EN
EN1
PGND
AGND
CBYP
CIN1
CPA
CLDO2
3.8mm
CIN2
VPA
CLDO1
LPA
LDO1
VIN
LDO2
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
5.5mm
Figure 3. Recommended PCB Layout
18
______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
IN1A
Li+ BATTERY
MAX8805W
MAX8805X
MAX8805Y
MAX8805Z
2.2μF IN1B
REFIN
DAC
LX
2MHz OR 4MHz
BUCK
1μH OR
2.2μH*
PBA
PBB
BASEBAND
PROCESSOR
2.2μF
PGND
PA_EN
GPIO
HP
GPIO
EN1
GPIO
IN
PA1
CONTROL
EN2
GPIO
EN/BIAS
REFBP
IN2
REF
1μF
AGND
0.22μF
LDO1
0.1μF
LDO1
LDO2
LDO2
0.1μF
EN/BIAS
IN
PA2
*1μH FDK MIPS 2520D1R0
2.2μH FDK MIPF 2520D2R2
Figure 4. Typical Application Circuit Using LDOs for PA Enable/Bias
______________________________________________________________________________________
19
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
IN1A
Li+ BATTERY
MAX8805W
MAX8805X
MAX8805Y
MAX8805Z
2.2μF IN1B
REFIN
DAC
LX
2MHz OR 4MHz
BUCK
1μH OR
2.2μH*
PBA
PBB
BASEBAND
PROCESSOR
2.2μF
PGND
GPIO
PA_EN
HP
GPIO
EN1
GPIO
IN
PA
CONTROL
EN2
GPIO
REFBP
IN2
REF
2.2μF
AGND
0.22μF
LDO1
IN
1μF
RF RECEIVER
LDO1
LDO2
LDO2
IN
1μF
RF TRANSMITTER
*1μH FDK MIPS 2520D1R0
2.2μH FDK MIPF 2520D2R2
Figure 5. Typical Application Circuit Using LDOs for RF Power
20
______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
Typical Operating Circuit
TOP VIEW
REFBP
A1
AGND
A2
REFIN
A3
PGND
A4
VPA
0.4V TO VBATT
BATT
2.7V TO 5.5V
2.2μF
IN1A
PAA
IN1B
PAB
LX
LDO2
B1
PA_EN
B2
EN2
B3
LX
B4
PA ON/OFF
HP
IN1B
IN1A
C1
C2
C3
C4
LDO1
EN1
PAB
PAA
D1
D2
D3
D4
PA_EN
2.2μF
PGND
REFBP
ANALOG CONTROL
IN2
1μH
MAX8805X
MAX8805Z
REFIN
HP
AGND
LDO1 ON/OFF
EN1
LDO1
LDO2 ON/OFF
EN2
VLDO1 UP
TO 200mA
LDO2
VLDO2 UP
TO 200mA
FORCED BYPASS
BATT
2.7V TO 5.5V
IN2
(BUMP IN BOTTOM)
16-Bump, 2mm × 2mm WLP
Chip Information
PROCESS: BiCMOS
______________________________________________________________________________________
21
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
Pin Configuration
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.)
16L WLP.EPS
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
Revision History
Pages changed at Rev 1: 2–7, 9, 10, 11, 14, 15
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.
22 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2007 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products. Inc.