MAX8805ZEWECE+T [MAXIM]
Switching Regulator;
| 型号： | MAX8805ZEWECE+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Switching Regulator |
| 文件： | 总24页 (文件大小：876K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-0777; Rev 5; 2/10
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
WY/MAX805Z
General Description
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 medium-
and 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 bias-
ing are also integrated.
o 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
V
BATT
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
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.
2% Gain Accuracy
Tiny External Components
o Dual Low-Noise LDOs
Low 35µV
(typ) Output Noise
RMS
High 70dB (typ) PSRR
Guaranteed 200mA Output Drive Capability
Individual ON/OFF Control
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.
o Low 0.1µA Shutdown Current
o 2.7V to 5.5V Supply Voltage Range
o Thermal Shutdown
o Tiny 2mm x 2mm x 0.7mm WLP and UCSP
Packages (4 x 4 Grid)
Applications
WCDMA/NCDMA Cellular Handsets
The LDOs in the MAX8805W/MAX8805X/MAX8805Y/
MAX8805Z are designed for low-noise operation
Wireless PDAs
Smartphones
(35µV
typ). Each LDO is individually enabled
RMS
through its own logic control interface.
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z are
available in 16-bump, 2mm x 2mm WLP and UCSP™
packages (0.7mm max height).
Pin Configuration appears at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
Ordering Information
PART
MAX8805WERExy+T*
MAX8805XERExy+T*
MAX8805YERExy+T*
MAX8805ZERExy+T*
PIN-PACKAGE
16 UCSP
SWITCHING FREQUENCY
REFIN TO OUT GAIN
2MHz
4MHz
2MHz
4MHz
2.5V/V
2.5V/V
2V/V
16 UCSP
16 UCSP
16 UCSP
2V/V
+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.
Ordering Information continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
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.
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 and PAB Short Circuit to PGND or IN1_.............Continuous
PAA, PAB, PA_EN, HP to AGND....-0.3V to (V
LDO1, LDO2, EN1 to AGND ......................-0.3V to (V
IN2 to IN1B/IN1A...................................................-0.3V to +0.3V
PGND to AGND.....................................................-0.3V to +0.3V
LX Current ......................................................................0.7A
IN1A/IN1B and PAA/PAB Current .....................................2A
/V
+ 0.3V)
+ 0.3V)
Continuous Power Dissipation (T = +70°C)
IN1A IN1B
A
16-Bump UCSP (derate 12.5mW/°C above +70°C) ..........1W
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
IN2
RMS
RMS
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.
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
= V
= V
= V
= V
= V
= 3.6V, V
= 0V, V
= 0.9V (MAX8805Y/MAX8805Z), V = 0.72V
REFIN
IN1A
IN1B
IN2
PA_EN
EN1
EN2
HP
REFIN
(MAX8805W/MAX8805X), T = -40°C to +85°C. Typical values are at T =+25°C, unless otherwise noted.) (Note 1)
A
A
PARAMETER
INPUT SUPPLY
Input Voltage
CONDITIONS
MIN
TYP
MAX
UNITS
V
V
, V
, V
2.7
5.5
2.70
4
V
V
IN1A IN1B IN2
Input Undervoltage Threshold
, V
, V
rising, 180mV typical hysteresis
2.52
2.63
0.1
IN1A IN1B IN2
T
T
= +25°C
= +85°C
A
A
Shutdown Supply Current
V
= V
= V
EN2
= 0V
LDO2
µA
PA_EN
EN1
0.1
V
V
= 0V, I
= I
= 0mA
150
3500
5000
150
250
PA_EN
LDO1
MAX8805W/MAX8805Y
MAX8805X/MAX8805Z
= V
= 0V, I = 0mA,
PA
EN1
EN2
No-Load Supply Current
µA
switching
V
= V
= 0V, V = 3.6V
HP
EN1
EN2
THERMAL PROTECTION
Thermal Shutdown
T
rising, 20°C typical hysteresis
+160
°C
A
LOGIC CONTROL
PA_EN, EN1, EN2, HP Logic-
Input High Voltage
2.7V ≤ V
2.7V ≤ V
= V
= V
= V
= V
≤ 5.5V
1.4
V
V
IN1A
IN1A
IN1B
IN1B
IN2
IN2
PA_EN, EN1, EN2, HP Logic-
Input Low Voltage
≤ 5.5V
0.4
1
T
T
= +25°C
= +85°C
0.01
0.1
A
Logic-Input Current
(PA_EN, EN1, EN2, HP)
V
= 0V or V = V = 5.5V
IN1A
µA
IL
IH
A
REFIN
WY/MAX805Z
MAX8805Y/MAX8805Z
MAX8805W/MAX8805X
0.1
0.1
2.2
REFIN Common-Mode Range
V
1.76
V
= 0.4V, 0.9V, 1.7V,
REFIN
MAX8805Y/MAX8805Z
MAX8805W/MAX8805X
1.96
2.45
2.00
2.50
2.04
2.55
2.2V (I = 0mA)
LX
REFIN to PA_ Gain
V/V
kΩ
V
= 0.32V, 0.75V,
REFIN
1.32V, 1.76V (I = 0mA)
LX
MAX8805Y/MAX8805Z
MAX8805W/MAX8805X
540
320
REFIN Input Resistance
2
_______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
WY/MAX805Z
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
= V
= V
= V
= V
= 3.6V, V
= 0V, V
= 0.9V (MAX8805Y/MAX8805Z), V = 0.72V
REFIN
IN1A
IN1B
IN2
PA_EN
EN1
EN2
HP
REFIN
(MAX8805W/MAX8805X), T = -40°C to +85°C. Typical values are at T =+25°C, unless otherwise noted.) (Note 1)
A
A
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
0.44 x 0.465 x 0.48 x
MAX8805Y/MAX8805Z
V
V
V
IN2
IN2
IN2
REFIN
Dual Mode™ Threshold
V
rising, 50mV hysteresis
V
REFIN
0.36 x 0.372 x 0.39 x
MAX8805W/MAX8805X
V
V
V
IN2
IN2
IN2
LX
p-channel MOSFET switch, I = -40mA
0.18
0.15
0.1
0.6
0.6
5
LX
On-Resistance
Ω
µA
A
n-channel MOSFET rectifier, I = 40mA
LX
T
A
T
A
= +25°C
= +85°C
V
V
= V
= 0V
= V
= 5.5V,
IN2
IN1A
IN1B
LX Leakage Current
LX
1
MAX8805Y/MAX8805Z
MAX8805W/MAX8805X
0.7
0.75
0.5
0.9
1.1
1.15
0.9
Peak Current Limit
(p-Channel MOSFET)
V
= 0V
LX
0.95
0.7
MAX8805Y/MAX8805Z
MAX8805W/MAX8805X
MAX8805Y/MAX8805Z
MAX8805W/MAX8805X
From PA_EN rising to LX rising
Valley Current Limit
(n-Channel MOSFET)
A
0.55
0.75
0.1
0.95
Minimum On- and Off-Times
µs
µs
0.07
150
Power-Up Delay
250
0.1
BYPASS
T
T
= +25°C
= +85°C
0.060
0.1
A
p-channel MOSFET bypass,
On-Resistance
Ω
A
A
I
= -90mA
OUT
A
Bypass Current Limit
V
_ = 0V
0.8
0.7
1.2
1.8
1.1
PA
LX
MAX8805Y/MAX8805Z
MAX8805W/MAX8805X
MAX8805Y/MAX8805Z
MAX8805W/MAX8805X
0.9
Step-Down Current Limit in Bypass
V
= 0V
0.75
1.5
0.95
2.1
1.15
2.9
Total Bypass Current Limit
V
= V _ = 0V
A
LX
PA
1.55
2.15
0.01
1
2.95
10
T
= +25°C
= +85°C
A
A
V
V
= V
= V
= 0V
= 5.5V,
IN2
IN1A
PAA
IN1B
Bypass Off-Leakage Current
µA
= V
PAB
T
LDO1
MAX8805_E_EAA+T
MAX8805_E_EBC+T
MAX8805_E_ECC+T
MAX8805_E_EDD+T
MAX8805_E_EEE+T
MAX8805_E_EGG+T
1.746
2.425
2.619
2.716
2.765
2.910
200
1.8
2.5
2.7
2.8
2.85
3.0
1.854
2.575
2.781
2.884
2.936
3.090
V
V
= 5.5V, I
= 3.4V, I
= 1mA;
= 100mA
IN2
IN2
LDO1
LDO1
Output Voltage V
V
LDO1
Output Current
Current Limit
mA
mA
mV
mV
mV
dB
V
= 0V
250
550
70
750
200
LDO1
Dropout Voltage
Line Regulation
Load Regulation
I
= 100mA, T = +25°C (V
≥ 2.5V)
LDO1
A
LDO1
V
stepped from 3.5V to 5.5V, I
= 100mA
LDO1
2.4
25
IN2
I
stepped from 50µA to 200mA
LDO1
Power-Supply Rejection
Dual Mode is a trademark of Maxim Integrated Products, Inc.
_______________________________________________________________________________________
10Hz to 10kHz, C
= 1µF, I
= 30mA
70
LDO1
LDO1
3
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
= V
= V
= V
= V
= 3.6V, V
= 0V, V
= 0.9V (MAX8805Y/MAX8805Z), V = 0.72V
REFIN
IN1A
IN1B
IN2
PA_EN
EN1
EN2
HP
REFIN
(MAX8805W/MAX8805X), T = -40°C to +85°C. Typical values are at T =+25°C, unless otherwise noted.) (Note 1)
A
A
PARAMETER
Output Noise
CONDITIONS
MIN
TYP
35
100
1
MAX
UNITS
100Hz to 100kHz, C
= 1µF, I
= 30mA
µV
RMS
LDO1
LDO1
0 < I
0 < I
< 10mA
nF
µF
kΩ
LDO1
LDO1
Output Capacitor for Stable
Operation
< 200mA
Shutdown Output Impedance
V
= 0V
1
EN1
LDO2
MAX8805_E_EAA+T
MAX8805_E_EAC+T
MAX8805_E_EAD+T
MAX8805_E_EBE+T
MAX8805_E_EGG+T
1.746
2.619
2.716
2.765
2.910
200
1.8
2.7
1.854
2.781
2.884
2.936
3.090
V
V
= 5.5V, I
= 3.4V, I
= 1mA;
= 100mA
IN2
IN2
LDO2
Output Voltage V
2.8
V
LDO2
LDO2
2.85
3.0
Output Current
Current Limit
mA
mA
mV
mV
mV
V
= 0V
250
550
70
750
200
LDO2
Dropout Voltage
Line Regulation
Load Regulation
I
= 100mA, T = +25°C
LDO2
A
V
stepped from 3.5V to 5.5V, I
= 100mA
= 30mA
LDO2
2.4
25
IN2
LDO2
I
stepped from 50µA to 200mA
LDO2
Power-Supply Rejection
∆V / ∆V
10Hz to 10kHz, C
= 1µF, I
70
dB
LDO2
LDO2
IN2
Output Noise
100Hz to 100kHz, C
= 1µF, I
= 30mA
35
100
1
µV
RMS
LDO2
LDO2
0µA < I
0µA < I
< 10mA
nF
µF
kΩ
LDO2
LDO2
Output Capacitor for Stable
Operation
< 200mA
Shutdown Output Impedance
REFBP
V
= 0V
1
EN2
REFBP Output Voltage
REFBP Supply Rejection
0 ≤ I
≤ 1µA
1.237
1.250
0.2
1.263
5
V
REFBP
V
stepped from 2.55V to 5.5V
mV
IN2
Note 1: All devices are 100% production tested at T = +25°C. Limits over the operating temperature range are guaranteed by design.
A
WY/MAX805Z
4
_______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
WY/MAX805Z
Typical Operating Characteristics
(V
= V
= V
= 3.6V, V
= 1.2V, V
= 2.85V, V
= 2.85V, R = 7.5Ω, circuit of Figure 5, T = +25°C, unless oth-
IN1A
IN1B
IN2
PA_
LDO1
LDO2
PA
A
erwise noted.)
BYPASS MODE DROPOUT VOLTAGE
vs. PA LOAD CURRENT
PA STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT VOLTAGE (MAX8805X/MAX8805Z)
PA STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT VOLTAGE (MAX8805W/MAX8805Y)
100
100
140
120
100
80
V
= 3.2V
IN1
90
80
70
60
90
80
70
60
BYPASS MODE
= 4.2V
BYPASS MODE
= 4.2V
V
IN1
V
IN1
V
= 3.6V
IN1
V
= 3.6V
IN1
V
= 3.6V
IN1
V
IN1
= 3.2V
60
V
= 3.2V
IN1
40
20
R
= 7.5Ω
R
PA
= 7.5Ω
PA
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
OUTPUT VOLTAGE (V)
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
PA LOAD CURRENT (A)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
OUTPUT VOLTAGE (V)
PA STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT VOLTAGE (MAX8805W/MAX8805Y)
PA STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT VOLTAGE (MAX8805X/MAX8805Z)
100
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805X/MAX8805Z)
100
100
90
80
70
60
50
V
= 1.8V
PA_
90
80
70
60
90
80
70
60
BYPASS MODE
= 4.2V
BYPASS MODE
= 4.2V
V
IN1
V
IN1
V
IN1
= 3.2V
V
= 4.2V
V
= 3.6V
IN1
IN1
V
IN1
= 3.6V
V
= 3.6V
IN1
V
= 3.2V
IN1
V
= 3.2V
IN1
R
= 10Ω
R
= 10Ω
PA
PA
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
OUTPUT VOLTAGE (V)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
OUTPUT VOLTAGE (V)
0
100 200 300 400 500 600 700
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)
100
90
80
70
60
50
100
90
80
70
60
50
100
90
80
70
60
50
V = 1.2V
PA_
V
= 1.8V
V
= 1.2V
PA_
PA_
V
= 3.2V
V
= 4.2V
IN1
IN1
V
= 4.2V
V
= 3.6V
IN1
IN1
V
= 4.2V
IN1
V
= 3.2V
V
IN1
V
= 3.2V
= 3.6V
IN1
IN1
V
= 3.6V
IN1
0
100 200 300 400 500 600 700
LOAD CURRENT (mA)
0
100 200 300 400 500 600 700
LOAD CURRENT (mA)
0
100 200 300 400 500 600 700
LOAD CURRENT (mA)
_______________________________________________________________________________________
5
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
Typical Operating Characteristics (continued)
(V
= V
= V
= 3.6V, V
= 1.2V, V
= 2.85V, V
= 2.85V, R = 7.5Ω, circuit of Figure 5, T = +25°C, unless oth-
IN1A
IN1B
IN2
PA_
LDO1
LDO2 PA A
erwise noted.)
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805X/MAX8805Z)
PA STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT (MAX8805W/MAX8805Y)
100
100
90
80
70
60
50
V
= 0.6V
PA_
V
PA_
= 0.6V
90
80
70
60
50
V
= 4.2V
IN1
V
= 4.2V
IN1
V
= 3.2V
V
IN1
V
= 3.2V
= 3.6V
IN1
IN1
V
= 3.6V
IN1
0
100 200 300 400 500 600 700
LOAD CURRENT (mA)
0
100 200 300 400 500 600 700
LOAD CURRENT (mA)
PA STEP-DOWN CONVERTER OUTPUT
VOLTAGE vs. REFIN VOLTAGE
PA STEP-DOWN CONVERTER OUTPUT
VOLTAGE vs. LOAD CURRENT
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
1.25
1.20
1.15
1.10
1.05
MAX8805X/MAX8805Z
MAX8805W/MAX8805Y
MAX8805X/MAX8805W
MAX8805Y/MAX8805Z
0
0.4
0.8
1.2
1.6
2.0
0
100 200 300 400 500 600 700
LOAD CURRENT (mA)
REFIN VOLTAGE (V)
REFIN vs. REFIN TO OUT GAIN (MAX8805Y)
REFIN vs. REFIN TO OUT GAIN (MAX8805Z)
50
100
80
V
= 3.2V, NO LOAD
V
= 3.2V, NO LOAD
IN1
IN1
30
60
V
= 4.2V, NO LOAD
IN1
40
V
= 4.2V, NO LOAD
IN1
WY/MAX805Z
10
20
0
-10
-30
-50
-20
-40
-60
-80
-100
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)
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)
6
_______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
WY/MAX805Z
Typical Operating Characteristics (continued)
(V
= V
= V
= 3.6V, V
= 1.2V, V
= 2.85V, V
= 2.85V, R = 7.5Ω, circuit of Figure 5, T = +25°C, unless oth-
IN1A
IN1B
IN2
PA_
LDO1
LDO2
PA
A
erwise noted.)
REFIN vs. REFIN TO OUT GAIN (MAX8805W)
REFIN vs. REFIN TO OUT GAIN (MAX8805X)
50
30
10
50
V
= 3.2V, NO LOAD
IN1
V
= 3.2V, NO LOAD
IN1
30
10
V
= 4.2V, NO LOAD
IN1
V
= 4.2V, NO LOAD
IN1
-10
-30
-50
-10
-30
-50
0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3
REFIN VOLTAGE (V)
0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3
REFIN VOLTAGE (V)
PA STEP-DOWN CONVERTER LIGHT-LOAD
PA STEP-DOWN CONVERTER LIGHT-LOAD
SWITCHING WAVEFORMS (MAX8805W/MAX8805Y)
SWITCHING WAVEFORMS (MAX8805X/MAX8805Z)
MAX8805W/X/Y/Z toc19
MAX8805W/X/Y/Z toc18
V
V
PA_
PA_
20mV/div
20mV/div
AC-COUPLED
AC-COUPLED
I
I
LX
LX
200mA/div
2V/div
200mA/div
V
V
LX
LX
2V/div
V
PA_
= 1.2V, I = 50mA
PA_
V
= 1.2V, I = 50mA
PA_
PA_
400ns/div
400ns/div
PA STEP-DOWN HEAVY-LOAD
PA STEP-DOWN HEAVY-LOAD
SWITCHING WAVEFORMS (MAX8805X/MAX8805Z)
SWITCHING WAVEFORMS (MAX8805W/MAX8805Y)
MAX8805W/X/Y/Z toc20
MAX8805W/X/Y/Z toc21
V
V
PA_
AC-COUPLED
PA_
20mV/div
20mV/div
AC-COUPLED
I
LX
I
LX
500mA/div
500mA/div
V
V
LX
LX
2V/div
2V/div
V
= 1.2V, I = 500mA
V
= 1.2V, I = 500mA
PA_ PA_
PA_
PA_
400ns/div
400ns/div
_______________________________________________________________________________________
7
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
Typical Operating Characteristics (continued)
(V
= V
= V
= 3.6V, V
= 1.2V, V
= 2.85V, V
= 2.85V, R = 7.5Ω, circuit of Figure 5, T = +25°C, unless oth-
IN1A
IN1B
IN2
PA_
LDO1
LDO2 PA A
erwise noted.)
PA STEP-DOWN SOFT-START
PA STEP-DOWN SOFT-START
WAVEFORMS (MAX8805W/MAX8805Y)
WAVEFORMS (MAX8805X/MAX8805Z)
MAX8805W/X/Y/Z toc23
MAX8805W/X/Y/Z toc22
V
V
PA_EN
PA_EN
2V/div
1V/div
2V/div
1V/div
V
PA_
V
PA_
I
LX
I
LX
200mA/div
500mA/div
20µs/div
20µs/div
PA STEP-DOWN CONVERTER LINE
PA STEP-DOWN CONVERTER LINE
TRANSIENT RESPONSE (MAX8805X/MAX8805Z)
TRANSIENT RESPONSE (MAX8805W/MAX8805Y)
MAX8805W/X/Y/Z toc24
MAX8805W/X/Y/Z toc25
4.0V
4.0V
V
V
IN1_
IN1_
500mV/div
50mV/div
200mA/div
500mV/div
50mV/div
200mA/div
3.5V
V
V
PA_
PA_
AC-COUPLED
AC-COUPLED
I
LX
I
LX
10µs/div
10µs/div
PA STEP-DOWN CONVERTER LOAD
PA STEP-DOWN CONVERTER LOAD
TRANSIENT RESPONSE (MAX8805X/MAX8805Z)
TRANSIENT RESPONSE (MAX8805W/MAX8805Y)
MAX8805W/X/Y/Z toc26
MAX8805W/X/Y/Z toc27
500mA
500mA
I
I
PA_
PA_
0mA 500mA/div
500mA/div
0mA
0mA
500mA/div
500mA/div
0mA
WY/MAX805Z
I
LX
I
LX
V
V
PA_
100mV/div
PA_
100mV/div
AC-COUPLED
AC-COUPLED
10µs/div
10µs/div
8
_______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
WY/MAX805Z
Typical Operating Characteristics (continued)
(V
= V
= V
= 3.6V, V
= 1.2V, V
= 2.85V, V
= 2.85V, R = 7.5Ω, circuit of Figure 5, T = +25°C, unless oth-
IN1A
IN1B
IN2
PA_
LDO1
LDO2
PA
A
erwise noted.)
PA STEP-DOWN CONVERTER OUTPUT
VOLTAGE TRANSIENT RESPONSE
PA STEP-DOWN CONVERTER FORCED
BYPASS-FET TRANSIENT RESPONSE
(MAX8805Y/MAX8805Z)
(MAX8805Y/MAX8805Z)
MAX8805W/X/Y/Z toc28
MAX8805W/X/Y/Z toc29
1.5V
V
V
REFIN
500mV/div
HP
2V/div
2V/div
0V
0V
1V
3.6V
500mV/div
500mA/div
0.5V
V
0.5V
V
PA_
PA_
1.2V
1.2V
500mA/div
I
LX
I
LX
10µs/div
20µs/div
PA STEP-DOWN CONVERTER
BYPASS-FET TRANSIENT RESPONSE
PA STEP-DOWN CONVERTER OUTPUT
VOLTAGE TRANSIENT RESPONSE
(MAX8805W/MAX8805X)
(MAX8805W/MAX8805X)
MAX8805W/X/Y/Z toc31
MAX8805W/X/Y/Z toc30
2V
V
V
REFIN
2V/div
2V/div
500mV/div
500mV/div
HP
0V
0V
1.25V
3.6V
0.66V
0.66V
V
PA_
V
PA_
1.2V
1.2V
I
LX
I
LX
500mA/div
500mA/div
20µs/div
10µs/div
PA STEP-DOWN CONVERTER AUTOMATIC
BYPASS-FET TRANSIENT RESPONSE
PA STEP-DOWN CONVERTER AUTOMATIC
BYPASS-FET TRANSIENT RESPONSE
(MAX8805Y/MAX8805Z)
(MAX8805Y/MAX8805Z)
MAX8805W/X/Y/Z toc32
MAX8805W/X/Y/Z toc33
V
IS A 0.4V TO
REFIN
1.8V
2V SINUSOIDAL
SIGNAL
V
V
REFIN
REFIN
1V/div
2V/div
1V/div
1V/div
0.6V
0.6V
1.2V
3.6V
3.6V
V
PA_
1.2V
V
PA_
500mA/div
I
LX
I
LX
500mA/div
10µs/div
200µs/div
_______________________________________________________________________________________
9
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
Typical Operating Characteristics (continued)
(V
= V
= V
= 3.6V, V
= 1.2V, V
= 2.85V, V
= 2.85V, R = 7.5Ω, circuit of Figure 5, T = +25°C, unless oth-
IN1A
IN1B
IN2
PA_
LDO1
LDO2
PA
A
erwise noted.)
PA STEP-DOWN CONVERTER
AUTOMATIC BYPASS-FET TRANSIENT
PA STEP-DOWN CONVERTER AUTOMATIC
BYPASS-FET TRANSIENT RESPONSE
RESPONSE (MAX8805W/MAX8805X)
(MAX8805W/MAX8805X)
MAX8805W/X/Y/Z toc35
MAX8805W/X/Y/Z toc34
1.44V
1V/div
1V/div
0.48V
0.48V
1.2V
V
V
REFIN
REFIN
1V/div
2V/div
3.6V
3.6V
V
PA_
V
PA_
1.2V
V
IS A 0.48V TO
REFIN
2.1V SINSOIDAL
SIGNAL
500mA/div
500mA/div
I
LX
I
LX
200µs/div
10µs/div
PA STEP-DOWN CONVERTER SHUTDOWN
PA STEP-DOWN CONVERTER SHUTDOWN
RESPONSE (MAX8805X/MAX8805Z)
RESPONSE (MAX8805W/MAX8805Y)
MAX8805W/X/Y/Z toc37
MAX8805W/X/Y/Z toc36
2V
2V
V
V
PA_EN
PA_EN
2V/div
2V/div
1V/div
0V
0V
1.2V
1.2V
V
PA_
2V/div
V
PA_
I
LX
100mA/div
I
LX
100mA/div
10µs/div
10µs/div
LDO1, LDO2 SUPPLY CURRENT
vs. SUPPLY VOLTAGE
LDO1, LDO2 DROPOUT VOLTAGE
vs. LOAD CURRENT
200
150
100
50
150
120
90
60
30
0
WY/MAX805Z
0
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY VOLTAGE (V)
0
50
100
150
200
LOAD CURRENT (mA)
10 ______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
WY/MAX805Z
Typical Operating Characteristics (continued)
(V
= V
= V
= 3.6V, V
= 1.2V, V
= 2.85V, V
= 2.85V, R = 7.5Ω, circuit of Figure 5, T = +25°C, unless oth-
IN1A
IN1B
IN2
PA_
LDO1
LDO2 PA A
erwise noted.)
LDO OUTPUT NOISE SPECTRAL DENSITY
vs. FREQUENCY
LDO PSRR vs. FREQUENCY
80
70
60
50
40
30
20
10
1.0E+04
1.0E+03
1.0E+02
1.0E+01
I
= 30mA
LDO_
0.01
0.1
1
10
100
1000
0.01
0.1
1
10
100
1000
FREQUENCY (kHz)
FREQUENCY (kHz)
LDO1, LDO2 OUTPUT NOISE WAVEFORM
LDO LINE TRANSIENT RESPONSE
MAX8805W/X/Y/Z toc42
MAX8805W/X/Y/Z toc43
4.0V
4.0V
V
IN2
500mV/div
3.5V
50mV/div
V
5mV/div
LDO_
I
= 80mA
LDO_
400µs/div
20µs/div
LDO1, LDO2 LOAD TRANSIENT
LDO1, LDO2 TURN ON AND
SHUTDOWN RESPONSE
RESPONSE NEAR DROPOUT
MAX8805W/X/Y/Z toc44
MAX8805W/X/Y/Z toc45
80mA
V
EN1,2
2V/div
2V/div
0mA
I
100mA/div
0mA
LDO1
V
I
50mV/div
LDO1
LDO2
V
LDO1
80mA
100mA/div
0mA
0mA
2V/div
V
LDO2
50mV/div
V
LDO2
V
= V
+ 200mV
LDO1,2
IN2
20µs/div
1ms/div
______________________________________________________________________________________ 11
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
Pin Description
PIN
A1
NAME
REFBP
AGND
FUNCTION
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
Low-Noise Analog Ground
DAC-Controlled Input. The output of the PA step-down converter is regulated to 2 x V
for the
REFIN
A3
REFIN
MAX8805Y/MAX8805Z and 2.5 x V
for the MAX8805W/MAX8805X. When V
reaches 0.465 x V
REFIN IN2
REFIN
for the MAX8805Y/MAX8805Z and 0.372 x V
for the MAX8805W/MAX8805X, bypass mode is enabled.
IN2
A4
B1
PGND
LDO2
Power Ground for PA Step-Down Converter
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.
PA Step-Down Converter Enable Input. Connect to IN_ or logic-high for normal operation. Connect to GND
or logic-low for shutdown mode.
B2
PA_EN
LDO2 Enable Input. Connect to IN2 or logic-high for normal operation. Connect to AGND or logic-low for
shutdown mode.
B3
B4
EN2
LX
Inductor Connection. Connect an inductor from LX to the output of the PA step-down converter.
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.
C1
C2
IN2
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.
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.
IN1B,
IN1A
C3, C4
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.
D1
D2
LDO1
EN1
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
D3, D4
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.
WY/MAX805Z
12 ______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
WY/MAX805Z
IN1A
IN1B
BYPASS FET
R4
R5
PAA
PAB
C1
R3
CURRENT-LIMIT CONTROL
HP
PWM ERROR
COMPARATOR
R7
REFIN
LX
PWM LOGIC
C2
R6
PGND
STEP-DOWN CURRENT LIMIT
R2
R1
IN2
REFBP
AGND
BANDGAP
1.25V
REFERENCE
LDO1 CURRENT LIMIT
LDO1
ERROR AMP
BANDGAP
R9
EN1
EN2
CONTROL
LOGIC
R8
R7
PA_EN
BANDGAP
LDO2 CURRENT LIMIT
LDO2
ERROR AMP
R12
R11
R10
Figure 1. Block Diagram
______________________________________________________________________________________ 13
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
Step-Down Converter Bypass Mode
Detailed Description
During high-power transmission, the bypass mode con-
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z are
nects IN1A and IN1B directly to PAA and PAB with the
designed to dynamically power the PA in WCDMA and
internal 60mΩ (typ) bypass FET, while the step-down
NCDMA handsets. The devices contain a high-frequency,
converter is forced into 100% duty-cycle operation. The
high-efficiency step-down converter, and two LDOs.
low on-resistance in this mode provides low dropout,
The MAX8805Y/MAX8805Z step-down converters deliver
long battery life, and high output current capability.
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 60mΩ bypass FET connects the PA directly to
the battery during high-power transmission.
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 V
> 0.465 x V
(see Figure 2) and
IN2
REFIN
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.
MAX8805W/MAX8805X enter bypass mode automati-
cally when V > 0.372 x V . 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.
REFIN
IN2
2.5
5.0
4.5
2.0
1.5
1.0
0.5
0
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
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
IN2
PA_
REFIN
0
5
10 15 20 25 30 35 40 45 50
TIME (ms)
Figure 2. V
and V
with Automatic Entry/Exit into Bypass
PA_
IN2
Mode (MAX8805Y/MAX8805Z)
Shutdown Mode
WY/MAX805Z
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.
V
to V
gain is slightly less than 2V/V, and the
REFIN
OUT
MAX8805W/MAX8805X V
to V
gain is slightly
REFIN
OUT
Connect EN1 or EN2 to GND or logic-low to place
LDO1 or LDO2, respectively, in shutdown mode. In
less than 2.5V/V. The output voltage is aproximately:
= (REFIN to PA_Gain) x V - 1/2 x L x I
ESR LOAD
V
OUT
REFIN
14 ______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
WY/MAX805Z
shutdown, the outputs of the LDOs are pulled to ground
Table 1. LDO1 and LDO2 Output Voltage
Selection
through an internal 1kΩ resistor.
When the PA step-down and LDOs are all in shutdown,
FREQUENCY
(MHz)
LDO1
(V)
LDO2
(V)
the MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
enter a very low power state, where the input current
drops to 0.1µA (typ).
PART
MAX8805WE_EAA+T
MAX8805WE_EAE+T
MAX8805WE_EEE+T
MAX8805XE_EAA+T
MAX8805XE_EAE+T
MAX8805XE_EEE+T
MAX8805YE_EAA+T
MAX8805YE_EAE+T
MAX8805YE_EEE+T
MAX8805ZE_EAA+T
MAX8805ZE_EAE+T
MAX8805ZE_EEE+T
2
2
2
4
4
4
2
2
2
4
4
4
1.80
1.80
2.85
1.80
1.80
2.85
1.80
1.80
2.85
1.80
1.80
2.85
1.80
2.85
2.85
1.80
2.85
2.85
1.80
2.85
2.85
1.80
2.85
2.85
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.
Note: Contact the factory for other output-voltage options.
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.
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.
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
50mΩ to 150mΩ range. See Table 2 for suggested
inductors and manufacturers.
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
Output Capacitor Selection
For the PA step-down converter, the output capacitor
(C ) is required to keep the output voltage ripple small
PA
and ensure regulation loop stability. C must have low
PA
impedance at the switching frequency. Ceramic capaci-
tors with X5R or X7R dielectric are highly recommended
(R
) multiplied by the load current (see the Typical
DS(ON)
Operating Characteristics).
______________________________________________________________________________________ 15
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
Table 2. Suggested Inductors
INDUCTANCE
(µH)
ESR
(Ω)
CURRENT RATING
(mA)
DIMENSIONS
(mm)
MANUFACTURER
SERIES
1.0
1.5
2.2
0.07
0.10
0.13
1600
1400
1100
Coilcraft
LPO3310
3.3 x 3.3 x 1.0 = 11mm3
2.5 x 2.0 x 1.0 = 5mm3
1.0
1.5
2.2
0.05
0.07
0.08
1500
1500
1300
MIPF2520
FDK
1.3
2.0
0.09
0.11
1500
1200
MIPS2520
MIPF2016
2.5 x 2.0 x 1.0 = 5mm3
2.0 x 1.6 x 1.0 = 3.2mm3
2.5 x 2.0 x 1.0 = 5mm3
3.2 x 2.5 x 1.7 = 14mm3
1.0
2.2
0.11
1100
—
1.5
2.2
0.115
0.080
Hitachi
Murata
KSLI-252010
LQH32C_53
1.0
2.2
0.06
0.10
1000
790
1.2
1.5
2.2
0.08
0.09
0.12
590
520
440
Sumida
CDRH2D09
CDRH2D11
3.0 x 3.0 x 1.0 = 9mm3
3.2 x 3.2 x 1.2 = 12mm3
1.5
2.2
3.3
0.05
0.08
0.10
680
580
450
Taiyo Yuden
2.2
4.7
0.09
0.13
510
340
CB2518T
D3010FB
D2812C
2.5 x 1.8 x 2.0 = 9mm3
3.0 x 3.0 x 1.0 = 9mm3
3.0 x 3.0 x 1.2 = 11mm3
1.0
0.20
1170
1.2
2.2
0.09
0.15
860
640
TOKO
1.5
2.2
0.13
0.17
1230
1080
D310F
D312C
3.6 x 3.6 x 1.0 = 13mm3
3.6 x 3.6 x 1.2 = 16mm3
1.5
2.2
0.10
0.12
1290
1140
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.
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.
WY/MAX805Z
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-
Input Capacitor Selection
The input capacitor (C ) of the PA converter reduces
IN1
the current peaks drawn from the battery or input
power source and reduces switching noise in the
16 ______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
WY/MAX805Z
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z. The
impedance of C at the switching frequency should
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:
IN1
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.
P
DISS
= P x (1/η - 1) + I
x (V
- V
) +
LDO1
PA
PA
LDO1
- V
IN2
I
x (V
)
LDO2
IN2
LDO2
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.
where η
is the efficiency of the PA step-down con-
PA
PA
verter and P is the output power of the PA step-down
converter.
The maximum allowed power dissipation is:
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.
P
= (T
- T ) / θ
JMAX A JA
MAX
where (T
- T ) is the temperature difference
A
JMAX
between the MAX8805W/MAX8805X/MAX8805Y/
MAX8805Z die junction and the surrounding air; θ is
JA
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.
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 1kΩ pulldown resistor.
Connect C
close to IN1A/IN1B and PGND. Connect
IN1
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
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
PGND
AGND
C
BYP
C
C
IN1
PA
C
LDO2
C
IN2
VPA
L
PA
C
LDO1
VIN
5.5mm
Figure 3. Recommended PCB Layout
WY/MAX805Z
18 ______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
WY/MAX805Z
MAX8805W
MAX8805X
MAX8805Y
MAX8805Z
IN1A
IN1B
Li+ BATTERY
2.2µF
1µH OR
2.2µH*
LX
REFIN
2MHz OR 4MHz
BUCK
DAC
PAA
2.2µF
PAB
BASEBAND
PROCESSOR
PGND
PA_EN
GPIO
GPIO
GPIO
GPIO
HP
EN1
EN2
IN
PA1
CONTROL
EN/BIAS
REFBP
AGND
LDO1
IN2
REF
0.22µF
0.1µF
1µF
LDO1
LDO2
LDO2
0.1µF
EN/BIAS
PA2
IN
*1µH FDK MIPS 2520D1R0
2.2µH FDK MIPF 2520D2R2
Figure 4. Typical Application Circuit Using LDOs for PA Enable/Bias
______________________________________________________________________________________ 19
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
MAX8805W
MAX8805X
MAX8805Y
MAX8805Z
IN1A
IN1B
Li+ BATTERY
2.2µF
1µH OR
2.2µH*
LX
REFIN
2MHz OR 4MHz
BUCK
DAC
PAA
2.2µF
PAB
BASEBAND
PROCESSOR
PGND
PA_EN
GPIO
HP
EN1
EN2
IN
GPIO
GPIO
GPIO
PA
CONTROL
REFBP
AGND
LDO1
IN2
REF
0.22µF
1µF
2.2µF
IN
IN
RF RECEIVER
LDO1
LDO2
LDO2
RF TRANSMITTER
1µF
*1µH FDK MIPS 2520D1R0
2.2µH FDK MIPF 2520D2R2
WY/MAX805Z
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
WY/MAX805Z
Pin Configuration
Typical Operating Circuit
TOP VIEW
V
PA
BATT
2.7V TO 5.5V
0.4V TO V
BATT
REFBP
A1
AGND
REFIN
A3
PGND
A4
IN1A
IN1B
PAA
2.2µF
PAB
LX
A2
1µH
MAX8805X
MAX8805Z
2.2µF
LDO2
B1
PA_EN
B2
EN2
B3
LX
B4
PGND
PA_EN
REFIN
HP
PA ON/OFF
REFBP
ANALOG CONTROL
FORCED BYPASS
IN2
C1
HP
C2
IN1B
C3
IN1A
C4
AGND
LDO1
LDO1 ON/OFF
LDO2 ON/OFF
EN1
EN2
V
UP
LDO1
TO 200mA
LDO1
D1
EN1
D2
PAB
D3
PAA
D4
BATT
2.7V TO 5.5V
V
UP
IN2
LDO2
LDO2
TO 200mA
(BUMP IN BOTTOM)
16-Bump, 2mm × 2mm WLP and UCSP
Ordering Information (continued)
PART
MAX8805WEWExy+T*
MAX8805XEWExy+T*
MAX8805YEWExy+T*
MAX8805ZEWExy+T*
PIN-PACKAGE
SWITCHING FREQUENCY
REFIN TO OUT GAIN
16 WLP
16 WLP
16 WLP
16 WLP
2MHz
4MHz
2MHz
4MHz
2.5V/V
2.5V/V
2V/V
2V/V
+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.
Chip Information
PROCESS: BiCMOS
______________________________________________________________________________________ 21
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the
package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the
package regardless of RoHS status.
PACKAGE TYPE
16 UCSP
PACKAGE CODE
R162A2+1
DOCUMENT NO.
21-0226
16 WLP
W162B2+1
21-0200
WY/MAX805Z
22 ______________________________________________________________________________________
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
WY/MAX805Z
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the
package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the
package regardless of RoHS status.
______________________________________________________________________________________ 23
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
DESCRIPTION
2
3
4
5
3/08
5/08
9/08
2/10
Updating package information
21
5
Corrected maximum range of Y axis for TOC 03
Updated EC table, TOC 13, and Voltage-Positioning Load Regulation section
Added UCSP package
1, 2, 3, 6, 14
1–4, 15, 22
WY/MAX805Z
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.
24 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2010 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
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