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19-0777; Rev 0; 4/07
600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power
General Description
The 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 60m 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 (MAX8805Y) and 4MHz (MAX8805Z)--allowing optimization for smallest solution size or highest efficiency. Fast switching allows the use of small ceramic 2.2F input and output capacitors while maintaining low ripple voltage. The feedback network is integrated, further reducing external component count and total solution size. The MAX8805Y/MAX8805Z use an analog input driven by an external DAC to control the output voltage linearly for continuous PA power adjustment. At high duty cycle, the MAX8805Y/MAX8805Z automatically switch to the bypass mode, connecting the input to the output through a low-impedance (60m typ) MOSFET. The user can also enable the bypass mode directly through a logic-control input. The LDOs in the MAX8805Y/MAX8805Z are designed for low-noise operation (35VRMS typ). Each LDO is individually enabled through its own logic control interface. The MAX8805Y/MAX8805Z are available in a 16-bump, 2mm x 2mm WLP package (0.7mm max height).
Features
PA Step-Down Converter 7.5s (typ) Settling Time for 0.8V to 3.4V Output Voltage Change Dynamic Output Voltage Setting from 0.4V to VBATT 60m pFET and 100% Duty Cycle for Low Dropout 2MHz or 4MHz Switching Frequency Low Output-Voltage Ripple 600mA Output Drive Capability 2% Maximum Accuracy Tiny External Components Dual Low-Noise LDOs Low 35VRMS (typ) Output Noise High 70dB (typ) PSRR Guaranteed 200mA Output Drive Capability Individual ON/OFF Control Low 0.1A 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)
MAX8805Y/MAX8805Z
Typical Operating Circuit
BATT 2.7V TO 5.5V IN1A 2.2F IN1B PAA PAB LX 1H VPA 0.4V TO VBATT
Applications
WCDMA/NCDMA Cellular Handsets Wireless PDAs Smartphones
MAX8805Z
PA ON/OFF PA_EN REFIN HP EN1 EN2 AGND LDO1 PGND REFBP
2.2F
Ordering Information
PART PINPACKAGE PKG CODE W162B2+1 W162B2+1 SWITCHING FREQUENCY (MHz) 2 4
ANALOG CONTROL FORCED BYPASS LDO1 ON/OFF LDO2 ON/OFF BATT 2.7V TO 5.5V
VLDO1 UP TO 200mA
MAX8805YEWExy+T* 16 WLP-16 MAX8805ZEWExy+T* 16 WLP-16
IN2
LDO2
+Denotes a lead-free package. T = Tape and reel package. *xy is the output voltage code (see Table 1 in the Output Voltages section).
VLDO2 UP TO 200mA
Note: All devices are specified over the -40C to +85C operating temperature range.
Pin Configuration appears at end of data sheet.
1
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power MAX8805Y/MAX8805Z
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 = +70C) 16-Bump WLP (derate 12.5mW/C above +70C).............1W Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Bump Temperature (soldering, reflow) ............................+235C
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, TA = -40C to +85C. Typical values are at TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER INPUT SUPPLY Input Voltage Input Undervoltage Threshold Shutdown Supply Current VIN1A, VIN1B, VIN2 VIN1A, VIN1B, VIN2 rising, 180mV typical hysteresis VPA_EN = VEN1 = VEN2 = 0V VPA_EN = 0V, ILDO1 = ILDO2 = 0A No-Load Supply Current VEN1 = VEN2 = 0V, IPA = 0A, switching VEN1 = VEN2 = 0V, VHP = 3.6V THERMAL PROTECTION Thermal Shutdown LOGIC CONTROL PA_EN, EN1, EN2, HP LogicInput High Voltage PA_EN, EN1, EN2, HP LogicInput Low Voltage Logic-Input Current (PA_EN, EN1, EN2, HP) REFIN REFIN Common-Mode Range REFIN to PA_ Gain (Falling Edge) REFIN Input Resistance REFIN Dual ModeTM Threshold VREFIN rising, 50mV hysteresis 0.45 x VIN2 VREFIN = 0.4V, 0.9V, 1.7V, 2.2V 0.1 1.96 2.00 540 0.465 x VIN2 0.48 x VIN2 2.2 2.04 V V/V k V 2.7V VIN1A = VIN1B = VIN2 5.5V 2.7V VIN1A = VIN1B = VIN2 5.5V VIL = 0V or VIH = VIN1A = 5.5V TA = +25C TA = +85C 0.01 0.1 1.4 0.4 1 V V A TA rising, 20C typical hysteresis +160 C MAX8805Y MAX8805Z TA = +25C TA = +85C 2.7 2.52 2.63 0.1 0.1 150 3500 5000 150 250 A 5.5 2.70 4 V V A CONDITIONS MIN TYP MAX UNITS
Dual Mode is a trademark of Maxim Integrated Products, Inc.
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600mA 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, TA = -40C to +85C. Typical values are at TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER LX On-Resistance LX Leakage Current p-Channel MOSFET Peak Current Limit n-Channel MOSFET Valley Current Limit Minimum On- and Off-Times Power-Up Delay BYPASS On-Resistance Bypass Current Limit p-channel MOSFET bypass, IOUT = -90mA VPA = 0 TA = +25C TA = +85C 0.8 0.7 1.5 TA = +25C TA = +85C MAX8805YEWEAA+T MAX8805YEWEBC+T Output Voltage VLDO1 VIN2 = 5.5V, ILDO1 = 1mA; VIN2 = 3.4V, ILDO1 = 100mA MAX8805YEWECC+T MAX8805YEWEDD+T MAX8805YEWEEE+T MAX8805YEWEGG+T Output Current Current Limit Dropout Voltage Line Regulation Load Regulation Power-Supply Rejection VLDO1 / VIN2 Output Noise Output Capacitor for Stable Operation Shutdown Output Impedance VLDO1 = 0V ILDO1 = 100mA, TA = +25C (VLDO1 2.5V) VIN2 stepped from 3.5V to 5.5V, ILDO1 = 100mA ILDO1 stepped from 50A to 200mA 10Hz to 10kHz, CLDO1 = 1F, ILDO1 = 30mA 100Hz to 100kHz, CLDO1 = 1F, ILDO1 = 30mA 0 < ILDO1 < 10mA 0 < ILDO1 < 200mA VEN1 = 0V 1.746 2.425 2.619 2.716 2.765 2.910 200 250 550 70 2.4 25 70 35 100 1 1 750 200 0.060 0.1 1.2 0.9 2.1 0.01 1 1.8 2.5 2.7 2.8 2.85 3.0 1.854 2.575 2.781 2.884 2.936 3.090 mA mA mV mV mV dB VRMS nF F k V 1.8 1.1 2.9 10 0.1 A A A A From PA_EN rising to LX rising p-channel MOSFET switch, ILX = -40mA n-channel MOSFET rectifier, ILX = 40mA VIN1A = VIN1B = VIN2 = 5.5V, VLX = 0V VLX = 0V TA = +25C TA = +85C 0.7 0.5 0.18 0.15 0.1 1 0.9 0.7 0.1 150 250 1.1 0.9 0.6 0.6 5 A A A s s CONDITIONS MIN TYP MAX UNITS
MAX8805Y/MAX8805Z
Step-Down Current Limit in Bypass VLX = 0 Total Bypass Current Limit VLX = VPA = 0 Bypass Off-Leakage Current LDO1 VIN1A = VIN1B = VIN2 = 5.5V, VPAA = VPAB = 0V
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power MAX8805Y/MAX8805Z
ELECTRICAL CHARACTERISTICS (continued)
(VIN1A = VIN1B = VIN2 = VPA_EN = VEN1 = VEN2 = 3.6V, VHP = 0V, VREFIN = 0.9V, TA = -40C to +85C. Typical values are at TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER LDO2 MAX8805YEWEAA+T MAX8805YEWEAC+T Output Voltage VLDO2 VIN2 = 5.5V, ILDO2 = 1mA; VIN2 = 3.4V, ILDO2 = 100mA MAX8805YEWEAD+T MAX8805YEWEBE+T MAX8805YEWEGG+T Output Current Current Limit Dropout Voltage Line Regulation Load Regulation Power-Supply Rejection VLDO2 / VIN2 Output Noise Output Capacitor for Stable Operation Shutdown Output Impedance REFBP REFBP Output Voltage REFBP Supply Rejection 0 IREFBP 1A VIN2 stepped from 2.55V to 5.5V 1.237 1.250 0.2 1.263 5 V mV VLDO2 = 0V ILDO2 = 100mA, TA = +25C VIN2 stepped from 3.5V to 5.5V, ILDO2 = 100mA ILDO2 stepped from 50A to 200mA 10Hz to 10kHz, CLDO2 = 1F, ILDO2 = 30mA 100Hz to 100kHz, CLDO2 = 1F, ILDO2 = 30mA 0A < ILDO2 < 10mA 0A < ILDO2 < 200mA VEN2 = 0V 1.746 2.619 2.716 2.765 2.910 200 250 550 70 2.4 25 70 35 100 1 1 750 200 1.8 2.7 2.8 2.85 3.0 1.854 2.781 2.884 2.936 3.090 mA mA mV mV mV dB VRMS nF F k V CONDITIONS MIN TYP MAX UNITS
Note 1: All devices are 100% production tested at TA = +25C. Limits over the operating temperature range are guaranteed by design.
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power
Typical Operating Characteristics
(VIN1A = VIN1B = VIN2 = 3.6V, VPA = 1.2V, VLDO1 = 2.85V, VLDO2 = 2.85V, RPA = 7.5, circuit of Figure 5, TA = +25C, unless otherwise noted.)
BYPASS MODE DROPOUT VOLTAGE vs. PA LOAD CURRENT
BYPASS MODE DROPOUT VOLTAGE (mV)
MAX8805Y/Z toc01
MAX8805Y/MAX8805Z
PA STEP-DOWN CONVERTER EFFICIENCY vs. OUTPUT VOLTAGE (MAX8805Z)
MAX8805Y/Z toc02
PA STEP-DOWN CONVERTER EFFICIENCY vs. OUTPUT VOLTAGE (MAX8805Y)
MAX8805Y/Z toc03
140 120 VIN1 = 3.2V 100
100
100
90 EFFICIENCY (%)
BYPASS MODE VIN1 = 4.2V
90 EFFICIENCY (%)
BYPASS MODE VIN1 = 4.2V
80 60 40 20 VIN1 = 3.6V
80
VIN1 = 3.6V VIN1 = 3.2V
80
VIN1 = 3.6V VIN1 = 3.2V
70 RPA = 7.5
70 RPA = 7.5 60 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V)
0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 PA LOAD CURRENT (A)
60
PA STEP-DOWN CONVERTER EFFICIENCY vs. OUTPUT VOLTAGE (MAX8805Z)
MAX8805Y/Z toc04
PA STEP-DOWN CONVERTER EFFICIENCY vs. OUTPUT VOLTAGE (MAX8805Y)
MAX8805Y/Z toc05
PA STEP-DOWN CONVERTER EFFICIENCY vs. LOAD CURRENT (MAX8805Z)
VPA = 1.8V 90 EFFICIENCY (%) VIN1 = 3.2V
MAX8805Y/Z toc06
100
100
100
90 EFFICIENCY (%)
BYPASS MODE VIN1 = 4.2V
90 EFFICIENCY (%)
BYPASS MODE VIN1 = 4.2V
80
80
VIN1 = 3.6V VIN1 = 3.2V
80
VIN1 = 3.6V VIN1 = 3.2V
VIN1 = 3.6V
VIN1 = 4.2V
70
70 RPA = 10 60 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 OUTPUT VOLTAGE (V)
70 RPA = 10 60 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 OUTPUT VOLTAGE (V)
60
50 0 100 200 300 400 500 600 LOAD CURRENT (mA)
PA STEP-DOWN CONVERTER EFFICIENCY vs. LOAD CURRENT (MAX8805Y)
MAX8805Y/Z toc07
PA STEP-DOWN CONVERTER EFFICIENCY vs. LOAD CURRENT (MAX8805Z)
VPA = 1.2V 90 EFFICIENCY (%)
MAX8805Y/Z toc08
PA STEP-DOWN CONVERTER EFFICIENCY vs. LOAD CURRENT (MAX8805Y)
VPA = 1.2V 90 EFFICIENCY (%)
MAX8805Y/Z toc09
100 VPA = 1.8V 90 EFFICIENCY (%) VIN1 = 3.2V 80 VIN1 = 3.6V
100
100
VIN1 = 4.2V
80 VIN1 = 3.6V 70 VIN1 = 3.2V VIN1 = 4.2V
80
VIN1 = 3.6V VIN1 = 3.2V VIN1 = 4.2V
70
70
60
60
60
50 0 100 200 300 400 500 600 LOAD CURRENT (mA)
50 0 100 200 300 400 500 600 LOAD CURRENT (mA)
50 0 100 200 300 400 500 600 LOAD CURRENT (mA)
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power MAX8805Y/MAX8805Z
Typical Operating Characteristics (continued)
(VIN1A = VIN1B = VIN2 = 3.6V, VPA = 1.2V, VLDO1 = 2.85V, VLDO2 = 2.85V, RPA = 7.5, circuit of Figure 5, TA = +25C, unless otherwise noted.)
PA STEP-DOWN CONVERTER EFFICIENCY vs. LOAD CURRENT (MAX8805Z)
MAX8805Y/Z toc10
PA STEP-DOWN CONVERTER EFFICIENCY vs. LOAD CURRENT (MAX8805Y)
VPA = 0.6V 90 EFFICIENCY (%)
MAX8805Y/Z toc11
100 VPA = 0.6V 90 EFFICIENCY (%)
100
80
80 VIN1 = 4.2V 70 VIN1 = 3.6V VIN1 = 3.2V 60
70 VIN1 = 3.6V VIN1 = 4.2V 60 VIN1 = 3.2V
50 0 100 200 300 400 500 600 LOAD CURRENT (mA)
50 0 100 200 300 400 500 600 LOAD CURRENT (mA)
PA STEP-DOWN CONVERTER OUTPUT VOLTAGE vs. LOAD CURRENT
MAX8805Y/Z toc12
PA STEP-DOWN CONVERTER OUTPUT VOLTAGE vs. REFIN VOLTAGE
MAX8805Y/Z toc13
1.25
4.0 3.5 OUTPUT VOLTAGE (V) 3.0 2.5 2.0 1.5 1.0
OUTPUT VOLTAGE (V)
1.20
MAX8805Y
1.15
MAX8805Z
1.10
1.05 0 100 200 300 400 500 600 LOAD CURRENT (mA)
0.5 0 0.4 0.8 1.2 1.6 2.0 REFIN VOLTAGE (V)
REFIN vs. REFIN TO OUT GAIN (MAX8805Z)
MAX8805Y/Z toc14
REFIN vs. REFIN TO OUT GAIN (MAX8805Y)
VIN1 = 3.2V, NO LOAD 30 VIN1 = 4.2V, NO LOAD
MAX8805Y/Z toc15
100 80 OUTPUT VOLTAGE ERROR (mV) 60 40 20 0 -20 -40 -60 -80 -100 VIN1 = 4.2V, NO LOAD VIN1 = 3.2V, NO LOAD
50 OUTPUT VOLTAGE ERROR (mV)
10
-10
-30
-50 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)
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600mA 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 = 7.5, circuit of Figure 5, TA = +25C, unless otherwise noted.)
PA STEP-DOWN CONVERTER LIGHT-LOAD SWITCHING WAVEFORMS (MAX8805Z)
MAX8805Y/Z toc16
MAX8805Y/MAX8805Z
PA STEP-DOWN CONVERTER LIGHT-LOAD SWITCHING WAVEFORMS (MAX8805Y)
MAX8805Y/Z toc17
VPA AC-COUPLED
20mV/div
VPA AC-COUPLED
20mV/div
ILX
200mA/div
ILX
200mA/div
VLX VPA = 1.2V, IPA = 50mA 400ns/div
2V/div
VLX VPA = 1.2V, IPA = 50mA 400ns/div
2V/div
PA STEP-DOWN HEAVY-LOAD SWITCHING WAVEFORMS (MAX8805Z)
MAX8805Y/Z toc18
PA STEP-DOWN HEAVY-LOAD SWITCHING WAVEFORMS (MAX8805Y)
MAX8805Y/Z toc19
VPA AC-COUPLED ILX
20mV/div
VPA AC-COUPLED ILX
20mV/div
500mA/div
500mA/div
VLX VPA = 1.2V, IPA = 500mA 400ns/div
2V/div
VLX VPA = 1.2V, IPA = 500mA 400ns/div
2V/div
PA STEP-DOWN SOFT-START WAVEFORMS (MAX8805Z)
MAX8805Y/Z toc20
PA STEP-DOWN SOFT-START WAVEFORMS (MAX8805Y)
MAX8805Y/Z toc21
VPA_EN
2V/div
VPA_EN
2V/div
VPA
1V/div
VPA
1V/div
ILX
500mA/div
ILX
200mA/div
20s/div
20s/div
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power MAX8805Y/MAX8805Z
Typical Operating Characteristics (continued)
(VIN1A = VIN1B = VIN2 = 3.6V, VPA = 1.2V, VLDO1 = 2.85V, VLDO2 = 2.85V, RPA = 7.5, circuit of Figure 5, TA = +25C, unless otherwise noted.)
PA STEP-DOWN CONVERTER LINE TRANSIENT RESPONSE (MAX8805Z)
MAX8805Y/Z toc22
PA STEP-DOWN CONVERTER LINE TRANSIENT RESPONSE (MAX8805Y)
MAX8805Y/Z toc23
4.0V VIN1 3.5V
4.0V 500mV/div VIN1
4.0V 3.5V
4.0V 500mV/div
VPA AC-COUPLED
50mV/div
VPA AC-COUPLED
50mV/div
ILX
200mA/div
ILX
200mA/div
10s/div
10s/div
PA STEP-DOWN CONVERTER LOAD TRANSIENT RESPONSE (MAX8805Z)
MAX8805Y/Z toc24
PA STEP-DOWN CONVERTER LOAD TRANSIENT RESPONSE (MAX8805Y)
MAX8805Y/Z toc25
500mA IPA 0mA 0mA 500mA/div IPA 0mA
500mA 0mA 500mA/div
ILX
500mA/div
ILX
500mA/div
VPA AC-COUPLED
100mV/div
VPA AC-COUPLED
100mV/div
10s/div
10s/div
PA STEP-DOWN CONVERTER OUTPUT VOLTAGE TRANSIENT RESPONSE
MAX8805Y/Z toc26
PA STEP-DOWN CONVERTER FORCED BYPASS-FET TRANSIENT RESPONSE
MAX8805Y/Z toc27
0.5V VREFIN 1V VPA 0.5V 0.5V 500mV/div VPA 1.2V 500mV/div VHP 0V 3.6V 2V/div 1.2V 0V 2V/div
ILX
500mA/div
ILX
500mA/div
10s/div
20s/div
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600mA 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 = 7.5, circuit of Figure 5, TA = +25C, unless otherwise noted.)
PA STEP-DOWN CONVERTER AUTOMATIC BYPASS-FET TRANSIENT RESPONSE
MAX8805Y/Z toc28
MAX8805Y/MAX8805Z
PA STEP-DOWN CONVERTER AUTOMATIC BYPASS-FET TRANSIENT RESPONSE
MAX8805Y/Z toc29
1.8V VREFIN 0.6V 3.6V VPA 1.2V 2V/div 1.2V 0.6V 1V/div
VREFIN IS A 0.4V TO 2V SINUSOIDAL VREFIN SIGNAL 3.6V
1V/div
1V/div VPA
ILX
500mA/div ILX 500mA/div
10s/div
200s/div
PA STEP-DOWN CONVERTER SHUTDOWN RESPONSE (MAX8805Y)
MAX8805Y/Z toc30
PA STEP-DOWN CONVERTER SHUTDOWN RESPONSE (MAX8805Z)
MAX8805Y/Z toc31
2V VPA_EN 1.2V VPA 1V/div VPA ILX 100mA/div ILX 0V 2V/div VPA_EN
2V 0V 1.2V 2V/div 2V/div
100mA/div
10s/div
10s/div
LDO1, LDO2 SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX8805Y/Z toc32
LDO1, LDO2 DROPOUT VOLTAGE vs. LOAD CURRENT
LDO1, LDO2 DROPOUT VOLTAGE (mV)
MAX8805Y/Z toc33
200 NO-LOAD SUPPLY CURRENT (A)
150
120
150
90
100
60
50
30
0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V)
0 0 50 100 LOAD CURRENT (mA) 150 200
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power MAX8805Y/MAX8805Z
Typical Operating Characteristics (continued)
(VIN1A = VIN1B = VIN2 = 3.6V, VPA = 1.2V, VLDO1 = 2.85V, VLDO2 = 2.85V, RPA = 7.5, circuit of Figure 5, TA = +25C, unless otherwise noted.)
LDO OUTPUT NOISE SPECTRAL DENSITY vs. FREQUENCY
MAX8805Y/Z toc34
LDO PSRR vs. FREQUENCY
80 70 60 PSRR (dB) 50 40 30 20 10 0.01 0.1 1 10 100 1000 FREQUENCY (kHz) 1.0E+04 OUTPUT NOISE DENSITY NOISE (nV/Hz)
1.0E+03
1.0E+02
ILDO = 30mA
1.0E+01 0.01 0.1 1 10 100 1000 FREQUENCY (kHz)
LDO1, LDO2 OUTPUT NOISE WAVEFORM
MAX8805Y/Z toc36
LDO LINE TRANSIENT RESPONSE
MAX8805Y/Z toc37
VIN2
4.0V 3.5V
4.0V 500mV/div
50mV/div
VLDO_
ILDO_ = 80mA 400s/div 20s/div
LDO1, LDO2 LOAD TRANSIENT RESPONSE NEAR DROPOUT
MAX8805Y/Z toc38
LDO1, LDO2 TURN ON AND SHUTDOWN RESPONSE
MAX8805Y/Z toc39
80mA ILDO1 0mA 0mA 100mA/div
VEN1,2
VLDO1 80mA ILDO2 0mA 0mA
50mV/div
VLDO1
100mA/div
VLDO2 VIN2 = VLDO1,2 + 200mV 20s/div
50mV/div
VLDO2
1ms/div
10
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MAX8805Y/Z toc35
5mV/div
2V/div
2V/div
2V/div
600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power
Pin Description
PIN A1 A2 A3 A4 B1 B2 B3 B4 C1 NAME REFBP AGND REFIN PGND LDO2 PA_EN EN2 LX IN2 FUNCTION Reference Noise Bypass. Bypass REFBP to AGND with a 0.22F ceramic capacitor to reduce noise on the LDO outputs. REFBP is internally pulled down through a 1k resistor during shutdown. Low-Noise Analog Ground DAC-Controlled Input. The output of the PA step-down converter is regulated to 2 x VREFIN. When VREFIN reaches 0.465 x VIN2, bypass mode is enabled. Power Ground for PA Step-Down Converter 200mA LDO Regulator 2 Output. Bypass LDO2 with a 1F ceramic capacitor as close as possible to LDO2 and AGND. LDO2 is internally pulled down through a 1k 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. LDO2 Enable Input. Connect to IN2 or logic-high for normal operation. Connect to AGND or logic-low for shutdown mode. 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 2.2F ceramic capacitor as close as possible to IN2 and AGND. Connect IN2 to the same source as IN1A and IN1B. 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 2.2F 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. 200mA LDO Regulator 1 Output. Bypass LDO1 with a 1F ceramic capacitor as close as possible to LDO1 and AGND. LDO1 is internally pulled down through a 1k resistor when this regulator is disabled. LDO1 Enable Input. Connect to IN2 or logic-high for normal operation. Connect to AGND or logic-low for shutdown mode.
MAX8805Y/MAX8805Z
C2
HP
C3, C4
IN1B, IN1A LDO1 EN1
D1 D2
D3, D4
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 2.2F ceramic capacitor as close as possible to PA_ and PGND.
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power MAX8805Y/MAX8805Z
IN1A IN1B R4 R5 BYPASS FET PAA C1 HP PWM ERROR COMPARATOR PWM LOGIC R6 C2 LX CURRENT-LIMIT CONTROL R3
PAB
R7 REFIN
PGND STEP-DOWN CURRENT LIMIT R2 R1
IN2 REFBP AGND BANDGAP 1.25V REFERENCE ERROR AMP BANDGAP EN1 EN2 PA_EN CONTROL LOGIC R8 R9 LDO1 CURRENT LIMIT LDO1
R7 BANDGAP LDO2 CURRENT LIMIT ERROR AMP R12 LDO2
R11
R10
Figure 1. Block Diagram
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power
Detailed Description
The MAX8805Y/MAX8805Z are designed to dynamically power the PA in WCDMA and NCDMA handsets. The devices contain a high-frequency, high-efficiency stepdown converter, and two LDOs. The step-down converter delivers over 600mA. 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 60m bypass FET connects the PA directly to the battery during high-power transmission. internal 60m (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.
MAX8805Y/MAX8805Z
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 VREFIN > 0.465 x VIN2 (see Figure 2). 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.
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.
5.0 4.5 4.0 3.5 IN2 AND PA_ VOLTAGE (V) 3.0 2.5 2.0 1.5 1.0 0.5 0 0 5 10 15 20 25 30 35 40 45 50 TIME (ms) IN2 PA_ REFIN
2.5
2.0 REFIN VOLTAGE (V)
1.5
1.0
0.5
0
Voltage-Positioning Load Regulation
The 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.
Figure 2. VIN2 and VPA_ with Automatic Entry/Exit into Bypass Mode
Shutdown Mode
Connect PA_EN to GND or logic-low to place the 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 shutdown, the outputs of the LDOs are pulled to ground through an internal 1k resistor. When the PA step-down and LDOs are all in shutdown, the MAX8805Y/MAX8805Z enter a very low power state, where the input current drops to 0.1A (typ).
Step-Down Converter Bypass Mode
During high-power transmission, the bypass mode connects IN1A and IN1B directly to PAA and PAB with the
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power MAX8805Y/MAX8805Z
Step-Down Converter Soft-Start
The MAX8805Y/MAX8805Z PA step-down converter has internal soft-start circuitry that limits inrush current at startup, reducing transients on the input source. Softstart is particularly useful for supplies with high output impedance such as Li+ and alkaline cells. See the SoftStart Waveforms in the Typical Operating Characteristics.
Table 1. LDO1 and LDO2 Output Voltage Selection
PART MAX8805YEWEAA+T MAX8805YEWEAE+T MAX8805YEWEEE+T MAX8805ZEWEAA+T MAX8805ZEWEAE+T MAX8805ZEWEEE+T FREQUENCY (MHz) 2 2 2 4 4 4 LDO1 (V) 1.80 1.80 2.85 1.80 1.80 2.85 LDO2 (V) 1.80 2.85 2.85 1.80 2.85 2.85
Analog REFIN Control
The MAX8805Y/MAX8805Z PA step-down converter uses REFIN to set the output voltage. The output voltage is regulated at twice the voltage applied at REFIN minus the load regulation. This allows the converter to operate in applications where dynamic voltage control is required.
Note: Contact the factory for other output-voltage options.
Thermal Shutdown
Thermal shutdown limits total power dissipation in the MAX8805Y/MAX8805Z. If the junction temperature exceeds +160C, 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 20C. This results in a pulsed output during continuous thermal-overload conditions. The inductor's DC current rating only needs to match the maximum load of the application because the 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 50m to 150m range. See Table 2 for suggested inductors and manufacturers.
Applications Information
Output Voltages
The MAX8805Y/MAX8805Z PA step-down converters set the PA_ output voltage to twice the voltage applied to REFIN. LDO1 and LDO2 output voltages are determined by the part number suffix, as shown in Table 1.
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 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 2.2F 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 0.1F capacitor for stable operation over the full temperature range. With rated maximum load currents, a minimum of 1F is recommended. Reduce output noise and improve loadtransient 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 2.2F or larger to ensure stability at temperatures below -10C. With X7R or X5R dielectrics, 1F is sufficient at all operating temperatures. These regulators are optimized for ceramic capacitors. Tantalum capacitors are not recommended.
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 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 MAX8805Y operates with a switching frequency of 2MHz and utilizes a 2.2H inductor. The MAX8805Z operates with a switching frequency of 4MHz and utilizes a 1H inductor. The higher switching frequency of the MAX8805Z allows the use of physically smaller inductors at the cost of slightly lower efficiency. The lower switching frequency of the MAX8805Y results in greater efficiency at the cost of a physically larger inductor. See the Typical Operating Characteristics for efficiency graphs for both the MAX8805Y and MAX8805Z.
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power
Table 2. Suggested Inductors
MANUFACTURER SERIES INDUCTANCE (H) 1.0 1.5 2.2 1.0 1.5 2.2 1.3 2.0 1.0 2.2 1.5 2.2 1.0 2.2 1.2 1.5 2.2 1.5 2.2 3.3 2.2 4.7 1.0 1.2 2.2 1.5 2.2 1.5 2.2 ESR () 0.07 0.10 0.13 0.05 0.07 0.08 0.09 0.11 0.11 0.115 0.080 0.06 0.10 0.08 0.09 0.12 0.05 0.08 0.10 0.09 0.13 0.20 0.09 0.15 0.13 0.17 0.10 0.12 CURRENT RATING (mA) 1600 1400 1100 1500 1500 1300 1500 1200 1100 -- 1000 790 590 520 440 680 580 450 510 340 1170 860 640 1230 1080 1290 1140 DIMENSIONS (mm) 3.3 x 3.3 x 1.0 = 11mm3
MAX8805Y/MAX8805Z
Coilcraft
LPO3310
MIPF2520 FDK
2.5 x 2.0 x 1.0 = 5mm3
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
Hitachi Murata
KSLI-252010 LQH32C_53
Sumida
CDRH2D09
3.0 x 3.0 x 1.0 = 9mm3
CDRH2D11 Taiyo Yuden CB2518T D3010FB D2812C TOKO D310F D312C
3.2 x 3.2 x 1.2 = 12mm3
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 3.6 x 3.6 x 1.0 = 13mm3 3.6 x 3.6 x 1.2 = 16mm3
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 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 2.2F 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 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 -10C. With X7R or X5R dielectrics, a capacitance equal to the sum is sufficient at all operating temperatures.
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power MAX8805Y/MAX8805Z
Thermal Considerations
In most applications, the MAX8805Y/MAX8805Z do not dissipate much heat due to their high efficiency. However, in applications where the 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 +160C, 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 1k pulldown resistor. The 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/PA - 1) + ILDO1 x (VIN2 - VLDO1) + ILDO2 x (VIN2 -VLDO2) where PA 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) / JA where (T JMAX - T A ) is the temperature difference between the MAX8805Y/MAX8805Z die junction and the surrounding air; JA 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.
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power MAX8805Y/MAX8805Z
PA_EN REFIN EN1 EN2 HP
AGND
PGND
CBYP
CIN1 CLDO2 3.8mm CIN2 VPA CLDO1 LPA LDO1 LDO2 VIN 5.5mm
CPA
Figure 3. Recommended PCB Layout
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power MAX8805Y/MAX8805Z
Li+ BATTERY
IN1A 2.2F IN1B
MAX8805Y/MAX8805Z
DAC
REFIN
LX 2MHz OR 4MHz BUCK PBA PBB
1H OR 2.2H*
2.2F
BASEBAND PROCESSOR GPIO GPIO GPIO GPIO PA_EN HP EN1 EN2 CONTROL
PGND
IN PA1 EN/BIAS
IN2 REF 1F
REFBP AGND LDO1 0.1F LDO1 0.22F
LDO2 LDO2 0.1F
EN/BIAS
IN PA2
*1H FDK MIPS 2520D1R0 2.2H FDK MIPF 2520D2R2
Figure 4. Typical Application Circuit Using LDOs for PA Enable/Bias
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power MAX8805Y/MAX8805Z
Li+ BATTERY
IN1A 2.2F IN1B
MAX8805Y/MAX8805Z
DAC
REFIN
LX 2MHz OR 4MHz BUCK PBA PBB
1H OR 2.2H*
2.2F
BASEBAND PROCESSOR GPIO GPIO GPIO GPIO PA_EN HP EN1 EN2 CONTROL
PGND
IN PA
IN2 REF 2.2F
REFBP AGND LDO1 1F LDO1 0.22F
IN
RF RECEIVER
LDO2 LDO2 1F
IN
RF TRANSMITTER
*1H FDK MIPS 2520D1R0 2.2H FDK MIPF 2520D2R2
Figure 5. Typical Application Circuit Using LDOs for RF Power
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power MAX8805Y/MAX8805Z
Pin Configuration
PROCESS: BiCMOS
TOP VIEW
REFBP A1 AGND A2 REFIN A3 PGND A4
Chip Information
LDO2 B1
PA_EN B2
EN2 B3
LX B4
IN2 C1 LDO1 D1
HP C2
IN1B C3 PAB D3
IN1A C4
EN1 D2
PAA D4
(BUMP IN BOTTOM) 16-Bump, 2mm x 2mm WLP
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600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power
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.)
MAX8805Y/MAX8805Z
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 ____________________ 21
(c) 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
16L WLP.EPS

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