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MAX8884Z
User Manual
15 pgs626.64 Kb0

Rainbow Electronics MAX8884Z User Manual

General Description
The MAX8884Y/MAX8884Z step-down converters with dual low-dropout (LDO) linear regulators are intended to power low-voltage microprocessors, DSPs, camera and Wi-Fi modules, or other point of load applications in portable devices. These ICs feature high efficiency with small external component size. The step-down converter output voltage is pin selectable between 1.2V and 1.8V, and provides guaranteed output current of 700mA. The 2/4MHz hysteretic-PWM control scheme allows for tiny external components and reduces no-load operating current to 50μA. Two low quiescent current, low-noise LDOs operate down to 2.7V supply voltage. Two switch­ing frequency options are available—MAX8884Y (2MHz) and MAX8884Z (4MHz)—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 MAX8884Y/MAX8884Z have individual enables for each output, maximizing flexibility.
The MAX8884Y/MAX8884Z are available in a 16-bump, 2mm x 2mm CSP package (0.7mm max height).
Applications
Cell Phones/Smartphones
PDA and Palmtop Computers
Portable MP3 and DVD Players
Digital Cameras, Camcorders
PCMCIA Cards
Handheld Instruments
Features
♦ Step-Down Converter
Pin-Selectable Output Voltage (1.2V/1.8V) 2MHz or 4MHz Switching Frequency Low-Output Voltage Ripple 700mA Output Drive Capability Simple Logic ON/OFF Control Tiny External Components
♦ Low-Noise LDOs
2 x 300mA LDO Pin-Selectable Output Voltage (LDO1) Low 26µV
RMS
(typ) Output Noise High 65dB (typ) PSRR Simple Logic ON/OFF Control
♦ Low 0.1µA Shutdown Current ♦ 2.7V to 5.5V Supply Voltage Range ♦ Thermal Shutdown ♦ Tiny, 2mm x 2mm x 0.65mm CSP Package (4x4 Grid)
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
________________________________________________________________
Maxim Integrated Products
1
19-4418; Rev 0; 4/09
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.
Typical Application Circuit appears at end of data sheet.
AGND
PGND
REFBP
NC1
BUCK_EN
LX
LDO2
LDO2_EN
MAX8884Y MAX8884Z
SEL
IN1A
IN2
IN1B
LDO1_EN
FB
LDO1
NC2
TOP VIEW
(BUMPS ON BOTTOM)
A1 A2 A3 A4
B1 B2 B3 B4
C1 C2 C3 C4
D1 D2 D3 D4
CSP
Pin Configuration
IN1A
LX
FB
2.2μH
AGND
BUCK_EN
LDO1_EN
LDO2_EN
IN2
BATT
2.7V TO 5.5V
BATT
2.7V TO 5.5V
BUCK ON/OFF
BUCK
1.2V/1.8V
REFBP
IN1B
LDO1 ON/OFF
LDO2 ON/OFF
LDO2
LDO1
V
LDO2
UP TO 300mA
V
LDO1
UP TO 300mA
PGND
SEL
2.2μF
2.2μF
BUCK/LDO1 VOLTAGE
SELECTION
MAX8884Y MAX8884Z
Typical Operating Circuit
Ordering Information
Note: All devices are specified over the -40°C to +85°C operat­ing temperature range.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
PART PIN-PACKAGE
MAX8884YEREKE+T 16 CSP 2MHz
MAX8884ZEREKE+T 16 CSP 4MHz
SWITCHING
FREQUENCY
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters with Dual 300mA LDO in 2mm x 2mm CSP
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
IN1A
= V
IN1B
= V
IN2
= V
LDO1_EN
= V
LDO2_EN
= V
BUCK_EN
= 3.6V. TA= -40°C to +85°C, typical values are at TA= +25°C, unless
otherwise noted.) (Note 1)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
IN1A, IN1B, IN2, REFBP to AGND ........................-0.3V to +6.0V
FB to PGND ...........................................................-0.3V to +6.0V
SEL, BUCK_EN to AGND...............-0.3V to (V
IN1A
/V
IN1B
+ 0.3V)
LDO1, LDO2, LDO1_EN, LDO2_EN
to AGND.................................................-0.3V to (V
IN2
+ 0.3V)
IN2 to IN1A, IN1B ..................................................-0.3V to +0.3V
AGND to PGND .....................................................-0.3V to +0.3V
IN1A, IN1B, LX Current .....................................................1A
RMS
Continuous Power Dissipation (TA= +70°C)
16-Bump CSP (derate 12.5mW/°C above +70°C) ..............1W
Operating Temperature .......................................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Bump Temperature*.........................................................+260°C
*
These ICs are constructed using a unique set of packaging techniques imposing a limit on the thermal profile used 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.
INPUT SUPPLY
Input Voltage V
Input Undervoltage Threshold V
Shutdown Supply Current
No-Load Supply Current
THERMAL PROTECTION
Thermal Shutdown TA rising, 20°C typical hysteresis +160 °C
LOGIC CONTROL
Logic Input-High Voltage (BUCK_EN, SEL, LDO1_EN, LDO2_EN)
PARAMETER CONDITIONS MIN TYP MAX UNITS
, V
, V
IN1A
, V
IN1A
V
BUCK_ EN
V
LDO2_EN
V
BUCK_ EN
V
LDO1_EN
2.7V V
IN1B
IN1B
IN1A
2.7 5.5 V
IN2
, V
rising, 180mV typical hysteres is 2.52 2.63 2.70 V
IN2
= V
LDO1_EN
=
= 0
= 0, I
= V
= V
LDO1
LDO2_EN
IN1B
= I
= 0, I
= V
TA= +25°C 0.1 4
T
= +85°C 0.1
A
= 0A 140 230 μA
LDO2
= 0A, no switching 50 80 μA
BUCK
 5.5V 1.3 V
IN2
μA
Logic Input-Low Voltage (BUCK_EN, SEL, LDO1_EN,
2.7V V
IN1A
= V
IN1B
= V
 5.5V 0.4 V
IN2
LDO2_EN)
Logic Input Current (BUCK_EN, SEL, LDO1_EN, LDO2_EN)
V
= 0 or VIH= V
IL
IN1A
= 5.5V
TA = +25°C 0.01 1
= +85°C 0.1
T
A
FB
Buc k Con verter Output Voltage
FB Leakage Current
SEL = AGND, I
= V
V
SEL
IN1A
V
= V
V
IN1A
FB
IN1B
= 0
= 0A 1.18 1.22 1.24 V
BUCK
, I
= 0A 1.78 1.80 1.85 V
BUCK
= V
= 5.5V,
IN2
TA = +25°C 0.01 1
T
= +85°C 1
A
LX
On-Resistance
p-channel MOSFET switch, ILX = -40mA 0.18 0.30
n-channel MOSFET rectifier, I
= 40mA 0.15 0.25
LX
μA
μA
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN1A
= V
IN1B
= V
IN2
= V
LDO1_EN
= V
LDO2_EN
= V
BUCK_EN
= 3.6V. TA= -40°C to +85°C, typical values are at TA= +25°C, unless
otherwise noted.) (Note 1)
Note 1: All devices are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed by
design.
LX Leakage Current
p-Channel MOSFET Peak Current Limit
n-Channel MOSFET Valley Current Lim it
n-Channel MOSFET Zero-Crossing Threshold
Min imum On-Time 0.07 μs
Minimum Off-Time 0.06 μs
Power-Up Delay From V
LDO1, LDO2
Output Voltage V
Output Voltage V
Output Current 300 mA
Current Lim it V
Dropout Voltage I
Line Regulation V
Load Regulation I
Power-Supply Rejection V
LDO_
Output Noise
Output Capacitor for Stable Operation
Shutdown Output Impedance V
Power-Up Delay From V
REFBP
REFBP Output Voltage 0  I
REFBP Supply Rejection V
PARAMETER CONDITIONS MIN TYP MAX UNITS
= V
V
IN1A
= 0
V
LX
= 0 0.8 1.0 1.2 A
V
LX
IN1B
= V
IN2
= 5.5V,
TA= +25°C 0.1 1
T
= +85°C 1
A
0.6 0.8 1.0 A
MAX8884Y_ 40
MAX8884Z_ 60
rising to VLX rising 120 250 μs
LDO_
LDO_
LDO_
LDO_
= 1mA; = 100mA
= 1mA; = 100mA
LDO_
= 30mA
LDO_
LDO_
= 30mA
LDO_
= 1.8V,
= 1.8V,
SEL = AGND 1.764 1.800 1.836
SEL = IN1_ 2.800
2.770 2.800 2.830 V
2.5V) 70 200 mV
LDO_
= 100mA 2.4 mV
LDO_
65 dB
26 μV
< 10mA 0.1
< 200mA 1
LDO_
< 300mA 2.2
LDO_
= V
LDO2_EN
= 0 100
rising to V
output ri sing 150 250 μs
LDO_
1μA 1.237 1.250 1.263 V
/V
IN2
LDO1
LDO2
BUCK_ EN
V
= 5.5V, I
IN2
V
= 3.4V, I
IN2
V
= 5.5V, I
IN2
V
= 3.4V, I
IN2
= 0 310 450 750 mA
LDO_
= 100mA, TA= +25°C (V
LDO_
stepped from 3.5V to 5.5V, I
IN2
stepped from 50μA to 200mA 25 mV
LDO_
10Hz to 100 kHz, V
= 2.2μF, I
C
LDO_
10Hz to 100 kHz, V C
= 2.2μF, I
LDO_
0 < I
LDO_
10mA < I
200mA < I
LDO1_EN
LDO_ EN
REFBP
stepped from 2.55V to 5.5V 0.2 5 mV
IN2
μA
mA
V
RMS
μF
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters with Dual 300mA LDO in 2mm x 2mm CSP
4 _______________________________________________________________________________________
STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT, V
OUT
= 1.8V
MAX8884Y/Z toc01
LOAD CURRENT (mA)
EFFICIENCY (%)
10010
40
50
60
70
80
90
100
30
1 1000
MAX8884Y, VIN = 3.2V
= 3.6V = 4.2V
MAX8884Z, V
IN
= 3.2V
= 3.6V = 4.2V
STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT, V
OUT
= 1.2V
MAX8884Y/Z toc02
LOAD CURRENT (mA)
EFFICIENCY (%)
10010
40
50
60
70
80
90
100
30
1 1000
MAX8884Y, VIN = 3.2V
= 3.6V = 4.2V
MAX8884Z, V
IN
= 3.2V
= 3.6V = 4.2V
STEP-DOWN CONVERTER NO-LOAD
SUPPLY CURRENT vs. INPUT VOLTAGE
MAX8884Y/Z toc03
INPUT VOLTAGE (V)
SUPPLY CURRENT (μA)
54321
50
100
150
200
250
300
0
06
V
BUCK_EN
= V
IN
V
LDO1_EN
= V
LDO2_EN
= 0
VIN FALLING
VIN RISING
MAX8884Y
MAX8884Z
STEP-DOWN OUTPUT VOLTAGE vs. LOAD
CURRENT (VOLTAGE POSITIONING)
MAX8884Y/Z toc04
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
10010
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
1.0 1 1000
SEL = IN1_
SEL = AGND
MAX8884Y STEP-DOWN CONVERTER
LIGHT LOAD SWITCHING WAVEFORMS
MAX8884Y/Z toc06
1μs/div
I
LX
V
OUT
V
LX
0A
2V/div
100mA/div
AC-COUPLED 10mV/div
0V
I
LOAD
= 50mA
MAX8884Z STEP-DOWN CONVERTER
HEAVY LOAD SWITCHING WAVEFORMS
MAX8884Y/Z toc07
200ns/div
I
LX
V
OUT
V
LX
0A
2V/div
500mA/div
AC-COUPLED 10mV/div
0V
I
LOAD
= 500mA
MAX8884Y STEP-DOWN CONVERTER
HEAVY LOAD SWITCHING WAVEFORMS
MAX8884Y/Z toc08
400ns/div
I
LX
V
OUT
V
LX
0A
2V/div
500mA/div
AC-COUPLED 10mV/div
0V
I
LOAD
= 500mA
Typical Operating Characteristics
(VIN= V
IN1A
= V
IN1B
= V
IN2
= 3.6V, V
BUCK
= 1.2V, V
LDO1
= 1.8V, V
LDO2
= 2.8V, MAX8884YEVKIT, TA= +25°C, unless otherwise noted.)
MAX8884Z STEP-DOWN CONVERTER
LIGHT LOAD SWITCHING WAVEFORMS
MAX8884Y/Z toc05
V
OUT
V
AC-COUPLED 20mV/div
I
LX
LX
400ns/div
100mA/div
0A
2V/div
0V
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
_______________________________________________________________________________________
5
MAX8884Z STEP-DOWN CONVERTER
LINE TRANSIENT RESPONSE
MAX8884Y/Z toc12
10μs/div
I
LX
V
IN
V
OUT
0A
1V/div
200mA/div
AC-COUPLED 20mV/div
I
LOAD
= 500mA
4V 4V
3.5V
MAX8884Y STEP-DOWN CONVERTER
LOAD TRANSIENT
MAX8884Y/Z toc14
20μs/div
I
LX
V
OUT
I
OUT
0A
1.8V DC OFFSET 100mV/div
500mA/div
500mA/div
0A
500mA
10mA 10mA
_______________________________________________________________________________________ 5
Typical Operating Characteristics (continued)
(VIN= V
IN1A
= V
IN1B
= V
IN2
= 3.6V, V
BUCK
= 1.2V, V
LDO1
= 1.8V, V
LDO2
= 2.8V, MAX8884YEVKIT, TA= +25°C, unless otherwise noted.)
MAX8884Z STEP-DOWN CONVERTER
LOAD TRANSIENT
MAX8884Y/Z toc13
20μs/div
V
OUT
I
LX
I
OUT
0A
500mA/div
0A
500mA/div
1.8V DC OFFSET 100mV/div
10mA10mA
500mA
MAX8884Z STEP-DOWN CONVERTER
SOFT-START WAVEFORMS
MAX8884Y/Z toc09
40μs/div
I
IN1
V
OUT
I
LX
V
BUCK_EN
0A
2V/div
500mA/div
0A
200mA/div
0V
1V/div
0V
I
LOAD
= 500mA
MAX8884Y STEP-DOWN CONVERTER
LINE TRANSIENT RESPONSE
4V 4V
V
IN
V
OUT
3.5V
MAX8884Y/Z toc11
1V/div
AC-COUPLED 20mV/div
MAX8884Y STEP-DOWN CONVERTER
V
BUCK_EN
SOFT-START WAVEFORMS
V
OUT
I
IN1
I
LX
40μs/div
I
LOAD
MAX8884Y/Z toc10
= 500mA
1V/div
0V
200mA/div
0A
500mA/div
0A
2V/div
0V
I
LX
I
= 500mA
LOAD
10μs/div
200mA/div
0A
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