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 switch-
ing frequency options are available—MAX8884Y (2MHz)
and MAX8884Z (4MHz)—allowing optimization for small-
est 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
oStep-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
oLow-Noise LDOs
2 x 300mA LDO
Pin-Selectable Output Voltage (LDO1)
Low 26µVRMS (typ) Output Noise
High 65dB (typ) PSRR
Simple Logic ON/OFF Control
oLow 0.1µA Shutdown Current
o2.7V to 5.5V Supply Voltage Range
oThermal Shutdown
oTiny, 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 1; 1/10
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.
EVALUATION KIT
AVAILABLE
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
VLDO2
UP TO 300mA
VLDO1
UP TO 300mA
PGND
SEL
2.2µF
2.2µF
BUCK/LDO1 VOLTAGE
SELECTION
MAX8884Y
MAX8884Z
Typical Operating Circuit
Ordering Information
PART PIN-PACKAGE SWITCHING
FREQUENCY
MAX8884YEREKE+T 16 CSP 2MHz
MAX8884ZEREKE+T 16 CSP 4MHz
Note: All devices are specified over the -40°C to +85°C operat-
ing temperature range.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN1A = VIN1B = VIN2 = VLDO1_EN = VLDO2_EN = VBUCK_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 (VIN1A/VIN1B + 0.3V)
LDO1, LDO2, LDO1_EN, LDO2_EN
to AGND.................................................-0.3V to (VIN2 + 0.3V)
IN2 to IN1A, IN1B ..................................................-0.3V to +0.3V
AGND to PGND .....................................................-0.3V to +0.3V
IN1A, IN1B, LX Current .....................................................1ARMS
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
PARAMETER CONDITIONS MIN TYP MAX UNITS
INPUT SUPPLY
Input Voltage VIN1A, VIN1B, VIN2 2.7 5.5 V
Input Undervoltage Threshold VIN1A, VIN1B, VIN2 rising, 180mV typical hysteresis 2.52 2.63 2.70 V
TA= +25°C 0.1 4
Shutdown Supply Current VBUCK_EN = VLDO1_EN =
VLDO2_EN = 0 TA= +85°C 0.1 µA
VBUCK_EN = 0, ILDO1 = ILDO2 = 0A 140 230 µA
No-Load Supply Current VLDO1_EN = VLDO2_EN = 0, IBUCK = 0A, no switching 50 80 µA
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)
2.7V VIN1A = VIN1B = VIN2 5.5V 1.3 V
Logic Input-Low Voltage
(BUCK_EN, SEL, LDO1_EN,
LDO2_EN)
2.7V VIN1A = VIN1B = VIN2 5.5V 0.4 V
TA = +25°C 0.01 1
Logic Input Current (BUCK_EN,
SEL, LDO1_EN, LDO2_EN) VIL = 0 or VIH = VIN1A = 5.5V TA = +85°C 0.1 µA
FB
SEL = AGND, IBUCK = 0A 1.18 1.22 1.24 V
Buck Converter Output Voltage VSEL = VIN1A, IBUCK = 0A 1.78 1.80 1.85 V
TA = +25°C 0.01 1
FB Leakage Current VIN1A = VIN1B = VIN2 = 5.5V,
VFB = 0 TA = +85°C 1 µA
LX
p-channel MOSFET switch, ILX = -40mA 0.18 0.30
On-Resistance n-channel MOSFET rectifier, ILX = 40mA 0.15 0.25
*
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.
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
_______________________________________________________________________________________ 3
PARAMETER CONDITIONS MIN TYP MAX UNITS
TA= +25°C 0.1 1
LX Leakage Current VIN1A = VIN1B = VIN2 = 5.5V,
VLX = 0 TA= +85°C 1 µA
p-Channel MOSFET Peak Current
Limit VLX = 0 0.8 1.0 1.2 A
n-Channel MOSFET Valley
Current Limit 0.6 0.8 1.0 A
MAX8884Y_ 40
n-Channel MOSFET
Zero-Crossing Threshold MAX8884Z_ 60
mA
Minimum On-Time 0.07 µs
Minimum Off-Time 0.06 µs
Power-Up Delay From VBUCK_EN rising to VLX rising 120 250 µs
LDO1, LDO2
SEL = AGND 1.764 1.800 1.836
Output Voltage VLDO1 VIN2 = 5.5V, ILDO_ = 1mA;
VIN2 = 3.4V, ILDO_ = 100mA SEL = IN1_ 2.800 V
Output Voltage VLDO2 VIN2 = 5.5V, ILDO_ = 1mA;
VIN2 = 3.4V, ILDO_ = 100mA 2.770 2.800 2.830 V
Output Current 300 mA
Current Limit VLDO_ = 0 310 450 750 mA
Dropout Voltage ILDO_ = 100mA, TA= +25°C (VLDO_ 2.5V) 70 200 mV
Line Regulation VIN2 stepped from 3.5V to 5.5V, ILDO_ = 100mA 2.4 mV
Load Regulation ILDO_ stepped from 50µA to 200mA 25 mV
Power-Supply Rejection
VLDO_/VIN2
10Hz to 100kHz, VLDO_ = 1.8V,
CLDO_ = 2.2µF, ILDO_ = 30mA 65 dB
Output Noise 10Hz to 100kHz, VLDO_ = 1.8V,
CLDO_ = 2.2µF, ILDO_ = 30mA 26 µVRMS
0 < ILDO_ < 10mA 0.1
10mA < ILDO_ < 200mA 1
Output Capacitor for Stable
Operation
200mA < ILDO_ < 300mA 2.2
µF
Shutdown Output Impedance VLDO1_EN = VLDO2_EN = 0 100
Power-Up Delay From VLDO_EN rising to VLDO_ output rising 150 250 µs
REFBP
REFBP Output Voltage 0 IREFBP 1µA 1.237 1.250 1.263 V
REFBP Supply Rejection VIN2 stepped from 2.55V to 5.5V 0.2 5 mV
ELECTRICAL CHARACTERISTICS (continued)
(VIN1A = VIN1B = VIN2 = VLDO1_EN = VLDO2_EN = VBUCK_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 TA= +25°C. Limits over the operating temperature range are guaranteed by
design.
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, VOUT = 1.8V
MAX8884Y/Z toc01
LOAD CURRENT (mA)
EFFICIENCY (%)
10010
40
50
60
70
80
90
100
30
1 1000
MAX8884Y, V
IN
= 3.2V
= 3.6V
= 4.2V
MAX8884Z, V
IN
= 3.2V
= 3.6V
= 4.2V
STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT, VOUT = 1.2V
MAX8884Y/Z toc02
LOAD CURRENT (mA)
EFFICIENCY (%)
10010
40
50
60
70
80
90
100
30
11000
MAX8884Y, V
IN
= 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
V
IN
FALLING
V
IN
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
MAX8884Z STEP-DOWN CONVERTER
LIGHT LOAD SWITCHING WAVEFORMS
MAX8884Y/Z toc05
400ns/div
ILX
VOUT
VLX
0A
2V/div
100mA/div
AC-COUPLED
20mV/div
0V
MAX8884Y STEP-DOWN CONVERTER
LIGHT LOAD SWITCHING WAVEFORMS
MAX8884Y/Z toc06
1µs/div
ILX
VOUT
VLX
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
ILX
VOUT
VLX
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
ILX
VOUT
VLX
0A
2V/div
500mA/div
AC-COUPLED
10mV/div
0V
I
LOAD
= 500mA
Typical Operating Characteristics
(VIN = VIN1A = VIN1B = VIN2 = 3.6V, VBUCK = 1.2V, VLDO1 = 1.8V, VLDO2 = 2.8V, MAX8884YEVKIT, TA= +25°C, unless otherwise noted.)
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
_______________________________________________________________________________________
5
_______________________________________________________________________________________ 5
Typical Operating Characteristics (continued)
(VIN = VIN1A = VIN1B = VIN2 = 3.6V, VBUCK = 1.2V, VLDO1 = 1.8V, VLDO2 = 2.8V, MAX8884YEVKIT, TA= +25°C, unless otherwise noted.)
MAX8884Y STEP-DOWN CONVERTER
LINE TRANSIENT RESPONSE
MAX8884Y/Z toc11
10
µ
s/div
ILX
VIN
VOUT
0A
1V/div
200mA/div
AC-COUPLED
20mV/div
I
LOAD
= 500mA
3.5V
4V 4V
MAX8884Z STEP-DOWN CONVERTER
LOAD TRANSIENT
MAX8884Y/Z toc13
20µs/div
VOUT
ILX
IOUT
0A
500mA/div
0A
500mA/div
1.8V DC OFFSET
100mV/div
10mA10mA
500mA
MAX8884Y STEP-DOWN CONVERTER
SOFT-START WAVEFORMS
MAX8884Y/Z toc10
40
µ
s/div
ILX
IIN1
VOUT
VBUCK_EN
0A
2V/div
500mA/div
0A
200mA/div
0V
1V/div
0V
I
LOAD
= 500mA
MAX8884Z STEP-DOWN CONVERTER
SOFT-START WAVEFORMS
MAX8884Y/Z toc09
40µs/div
IIN1
VOUT
ILX
VBUCK_EN
0A
2V/div
500mA/div
0A
200mA/div
0V
1V/div
0V
ILOAD = 500mA
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
6 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VIN = VIN1A = VIN1B = VIN2 = 3.6V, VBUCK = 1.2V, VLDO1 = 1.8V, VLDO2 = 2.8V, MAX8884YEVKIT, TA= +25°C, unless otherwise noted.)
LDO POWER SUPPLY
RIPPLE REJECTION, VOUT = 1.8V
MAX8884Y/Z toc18
FREQUENCY (kHz)
RIPPLE REJECTION (dB)
100100.1 1
10
20
30
40
50
60
70
80
0
0.01 1000
I
LDO
= 30mA
LDO OUTPUT VOLTAGE
NOISE WAVEFORM, VOUT_ = 1.8V
MAX8884Y/Z toc20
400
µ
s/div
MAX8884Y/MAX8884Z
LDO1 = 1.8 AT 30mA
VIN = 3.6V
50µV/div
VN = 26.1µV
RMS
,
f = 100Hz to 100kHz, I
LDO_
= 30mA
LDO2 DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX8884Y/Z toc17
LOAD CURRENT (mA)
DROPOUT VOLTAGE (V)
25020015010050
50
100
150
200
250
0
0300
LDO POWER SUPPLY
RIPPLE REJECTION, VOUT = 2.8V
MAX8884Y/Z toc19
FREQUENCY (kHz)
RIPPLE REJECTION (dB)
1001010.1
10
20
30
40
50
60
70
0
0.01 1000
I
LDO_
= 30mA
LDO1, LDO2 INPUT SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX8884Y/Z toc16
INPUT VOLTAGE (V)
SUPPLY CURRENT (µA)
54321
50
100
150
200
250
300
350
0
06
V
LDO1_EN
= V
LDO2_EN
= V
IN
,
V
BUCK_EN
= 0
MAX8884Y STEP-DOWN CONVERTER
SHUTDOWN WAVEFORMS
MAX8884Y/Z toc15
10µs/div
ILX
VOUT
VBUCK_EN
0V
1V/div
0V
5V/div
500mA/div
0A
I
LOAD
= 500mA
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
_______________________________________________________________________________________
7_______________________________________________________________________________________ 7
Typical Operating Characteristics (continued)
(VIN = VIN1A = VIN1B = VIN2 = 3.6V, VBUCK = 1.2V, VLDO1 = 1.8V, VLDO2 = 2.8V, MAX8884YEVKIT, TA= +25°C, unless otherwise noted.)
LDO1, LDO2 LOAD TRANSIENT RESPONSE
MAX8884Y/Z toc24
20µs/div
ILDO1
VLDO2
ILDO2
VLDO1 AC-COUPLED
10mV/div
AC-COUPLED
10mV/div
50mA/div
50mA/div
1mA 1mA
1mA 1mA
40mA
40mA
LDO1, LDO2 LINE TRANSIENT
MAX8884Y/Z toc23
10µs/div
VLDO1
VIN
VLDO2 AC-COUPLED
5mV/div
AC-COUPLED
5mV/div
1V/div
I
LDO1
= I
LDO2
= 100mA
4V 4V
3.5V
LDO OUTPUT-NOISE SPECTRAL DENSITY
vs. FREQUENCY, VLDO_ = 2.8V
MAX884Y/Z toc22
FREQUENCY (kHz)
1001010.1
100
1000
10,000
10
0.01 1000
I
LDO_
= 30mA
NOISE DENSITY (nV√(Hz))
LDO OUTPUT-NOISE SPECTRAL DENSITY
vs. FREQUENCY, VLDO_ = 1.8V
MAX884Y/Z toc21
FREQUENCY (kHz)
NOISE DENSITY (nV√(Hz))
1001010.1
100
1000
10,000
10
0.01 1000
I
LDO_
= 30mA
LDO1, LDO2 STARTUP
AND SHUTDOWN RESPONSE
MAX8884Y/Z toc26
400µs/div
VLDO1
VLDO1_EN =
VLDO2_EN
VLDO2 2V/div
0V
2V/div
0V
2V/div
0V
LDO1, LDO2 LOAD TRANSIENT
RESPONSE NEAR DROPOUT
MAX8884Y/Z toc25
20µs/div
ILDO1
VLDO2
ILDO2
VLDO1
AC-COUPLED
10mV/div
AC-COUPLED
10mV/div
50mA/div
50mA/div
1mA 1mA
40mA
1mA 1mA
40mA
V
IN2
= V
LDO2
+ 200mV
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
8 _______________________________________________________________________________________
REFBP SOFT-START
CREFBP = 0.15µF
MAX8884Y/Z toc28
100µs/div
VLDO1_EN
VREFBP
VLDO1 1V/div
0V
2V/div
0V
1V/div
0V
REFBP SOFT-START
CREFBP = 0.033µF
MAX8884Y/Z toc27
100
µ
s/div
VLDO1_EN
VREFBP
VLDO1 1V/div
0V
2V/div
0V
0V
1V/div
MAX8884Y SWITCHING FREQUENCY
vs. OUTPUT CURRENT (VOUT = 1.2V)
MAX8884Y/Z toc30
LOAD CURRENT (mA)
SWITCHING FREQUENCY (MHz)
700500300
1.2
1.4
1.6
1.8
2.0
2.2
2.4
1.0
100 900
VIN = 4.2V
VIN = 3.6V
VIN = 3V
CIN = COUT = 2.2µF, L = 2.2µH
MAX8884Y SWITCHING FREQUENCY
vs. OUTPUT CURRENT (VOUT = 1.8V)
MAX8884Y/Z toc29
LOAD CURRENT (mA)
SWITCHING FREQUENCY (MHz)
700500300
1.2
1.4
1.6
1.8
2.0
2.2
2.4
1.0
100 900
VIN = 4.2V
VIN = 3.6V
VIN = 3V
CIN = COUT = 2.2µF, L = 2.2µH
MAX8884Z SWITCHING FREQUENCY
vs. OUTPUT CURRENT (VOUT = 1.2V)
MAX8884Y/Z toc32
LOAD CURRENT (mA)
SWITCHING FREQUENCY (MHz)
700500300
3.0
4.0
4.5
3.5
5.0
2.5
100 900
CIN = COUT = 2.2µF, L = 2.2µH
VIN = 3.6V
VIN = 3V
VIN = 4.2V
MAX8884Z SWITCHING FREQUENCY
vs. OUTPUT CURRENT (VOUT = 1.8V)
MAX8884Y/Z toc31
LOAD CURRENT (mA)
SWITCHING FREQUENCY (MHz)
700500300
2.5
3.0
3.5
4.0
4.5
5.0
2.0
100 900
VIN = 4.2V
VIN = 3.6V
VIN = 3V
CIN = COUT = 2.2µF, L = 2.2µH
Typical Operating Characteristics (continued)
(VIN = VIN1A = VIN1B = VIN2 = 3.6V, VBUCK = 1.2V, VLDO1 = 1.8V, VLDO2 = 2.8V, MAX8884YEVKIT, TA= +25°C, unless otherwise noted.)
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
_______________________________________________________________________________________ 9
Detailed Description
The MAX8884Y/MAX8884Z are designed to power the
subcircuits within a system. These ICs contain a high-
frequency, high-efficiency step-down converter and two
LDOs. The step-down converter delivers 700mA with
either 1.2V or 1.8V selectable output voltage using SEL.
The hysteretic PWM control scheme provides extremely
fast transient response, while 2MHz and 4MHz switch-
ing frequency options allow the trade-off between effi-
ciency and the smallest external components. The
MAX8884Y/MAX8884Z linear regulators can be used to
power loads requiring a low output noise supply.
Step-Down Converter Control Scheme
A hysteretic PWM control scheme ensures high efficien-
cy, fast switching, fast transient response, low-output
voltage 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 output voltage is within regu-
lation, 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 volt-
age falls again below the regulation threshold. During
Pin Description
PIN NAME FUNCTION
A1 REFBP Reference Noise Bypass. Bypass REFBP to AGND with a 0.033µF ceramic capacitor to reduce noise
on the LDO outputs. REFBP is internally pulled to ground through a 1kΩ resistor during shutdown.
A2 AGND Low-Noise Analog Ground. Connect to common ground plane.
A3 NC1 No Internal Connection. Connect NC1 to ground.
A4 PGND Power Ground for Step-Down Converter. Connect to common ground plane.
B1 LDO2
300mA LDO Regulator 2 Output. For 300mA application, bypass LDO2 with a 2.2µF ceramic capacitor
as close as possible to LDO2 and AGND. For low-output current capability, up to 10mA, an output
capacitor of 0.1µF is sufficient to keep the output voltage stable. LDO2 is internally pulled to ground
through a 100Ω resistor when this regulator is disabled.
B2 BUCK_EN Step-Down Converter Enable Input. Connect BUCK_EN to IN1_ or logic-high for normal operation.
Connect BUCK_EN to AGND or logic-low for step-down shutdown mode.
B3 LDO2_EN LDO2 Enable Input. Connect LDO2_EN to IN2 or logic-high for normal operation. Connect LDO2_EN to
AGND or logic-low for LDO2 shutdown mode.
B4 LX Inductor Connection. Connect an inductor from LX to the output of the 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 4.7µF ceramic capacitor as close as possible to IN2 and
AGND. Connect IN2 to the same source as IN1A and IN1B.
C2 SEL Output Voltage Selection for LDO1 and Step-Down Converter. Connect to IN1_ or AGND for output
voltage selection. See Table 1.
C3, C4 IN1B, IN1A
Supply Voltage Input for Step-Down Converter. Connect IN1B and IN1A to a battery or supply voltage
from 2.7V to 5.5V. Bypass the connection of IN1B and IN1A with a 2.2µF ceramic capacitor as close as
possible to IN1B, IN1A, and PGND. IN1A and IN1B are internally connected together. Connect IN1A
and IN1B to the same source as IN2.
D1 LDO1
300mA LDO Regulator 1 Output. For 300mA application, bypass LDO1 with a 2.2µF ceramic capacitor
as close as possible to LDO1 and AGND. For low-output current capability, up to 10mA, an output
capacitor of 0.1µF is sufficient to keep output voltage stable. LDO1 is internally pulled to AGND
through a 100Ω resistor when this regulator is disabled.
D2 LDO1_EN LDO1 Enable Input. Connect LDO1_EN to IN2 or logic-high for normal operation. Connect LDO1_EN to
AGND or logic-low for LDO1 shutdown mode.
D3 NC2 No Internal Connection. Connect NC2 to ground.
D4 FB FB is Connected to the Internal Feedback Network
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
10 ______________________________________________________________________________________
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.
Hysteretic control is sometimes referred to as ripple con-
trol, since voltage ripple is used to control when the high-
side and low-side switches are turned on and off. To
ensure stability with low ESR ceramic output capacitors,
the MAX8884Y/MAX8884Z combine ripple from the out-
put with the ramp signal generated by the switching
node (LX). This is seen in Figure 2 with resistor R1 and
capacitor C1 providing the combined ripple signal.
Injecting ramp from the switch node also improves line
regulation, since the slope of the ramp adjusts with
changes in input voltage.
Hysteretic control has a significant advantage over fixed
frequency control schemes: fast transient response.
Hysteretic control uses an error comparator, instead of
an error amplifier with compensation, and there is no
fixed frequency clock. Therefore, a hysteretic converter
reacts virtually immediately to any load transient on the
output, without having to wait for a new clock pulse, or
for the output of the error amplifier to move, as with a
fixed-frequency converter.
With a fixed-frequency step-down converter, the magni-
tude of output voltage ripple is a function of the switching
frequency, inductor value, output capacitor and ESR,
and input and output voltage. Since the inductance value
and switching frequency are fixed, the output ripple
varies with changes in line voltage. With a hysteretic
step-down converter, since the ripple voltage is essen-
tially fixed, the switching frequency varies with changes
in line voltage. Some variation with load current is also
seen, however, this is part of what gives the hysteretic
converter its great transient response.
See the
Typical Operating Characteristics
section for
more information on how switching frequency can
change with load and line changes.
At inductor currents below 40mA (60mA), the MAX8884Y
(MAX8884Z) automatically switches to pulse-skipping
mode to improve light-load efficiency. Output voltage
ripple remains low at all loads, while the skip-mode
switching frequency remains ultrasonic down to 1mA
(typ) loads.
Voltage Positioning Load Regulation
The MAX8884Y/MAX8884Z step-down converters utilize
a unique feedback network. By taking a DC feedback
from the LX node through R1 in the
Block Diagram
, 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 capaci-
tors. To improve the load regulation, resistor R3 is
included in the feedback (see the
Block Diagram
). This
configuration yields load regulation equal to half the
inductor’s series resistance multiplied by the load cur-
rent. This voltage positioning load regulation greatly
reduces overshoot during load transients.
SEL Output Voltage Selection
SEL is used to determine the output voltage of the buck
converter and LDO1. See Table 1.
Shutdown Mode
Drive BUCK_EN to logic-low to place the MAX8884Y/
MAX8884Z step-down converter in shutdown mode. In
shutdown, the control circuitry, internal switching
MOSFET, and synchronous rectifier turn off and LX
becomes high impedance.
The LDOs are individually enabled. Connect LDO1_EN
and LDO2_EN to GND or logic-low to place LDO1 and
LDO2 in shutdown mode. In shutdown, the outputs of
the LDOs are pulled to ground through an internal
100Ωresistor.
When the step-down converter and all LDOs are in shut-
down, the MAX8884Y/MAX8884Z enter a very low-power
state, where the input current drops to 0.1µA (typ).
Step-Down Converter Soft-Start
The MAX8884Y/MAX8884Z step-down converter uses
internal soft-start circuitry to limit inrush current at startup,
reducing transients on the input source. Soft-start is partic-
ularly useful for supplies with high output impedance such
as Li+ and alkaline cells. See the soft-start waveforms in
the
Typical Operating Characteristics
.
VV IR
I load cu
BUCK BUCK NO LOAD LOAD DCR
LOAD
=−
×
=
__ 2
rrrent
R DC impedance of inductor
V
DCR
BUCK NO LO
=
__AAD V or V depending on SEL=12 18..
SEL
BUCK CONVERTER
OUTPUT VOLTAGE
(V)
LDO1
OUTPUT VOLTAGE
(V)
AGND 1.2 1.8
IN1_ 1.8 2.8
Table 1. SEL Output Voltage Selection
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
______________________________________________________________________________________ 11
Thermal Shutdown
Thermal shutdown limits total power dissipation in the
MAX8884Y/MAX8884Z. If the junction temperature
exceeds +160°C, thermal shutdown circuitry turns off
the MAX8884Y/MAX8884Z, allowing the ICs to cool.
The ICs turn on and begin soft-start after the junction
temperature cools by 20°C. This results in a pulsed out-
put during continuous thermal-overload conditions.
Applications Information
Output Voltages
The MAX8884Y/MAX8884Z DC-DC step-down convert-
er sets the BUCK and LDO1 output voltage based on
the state of SEL. See Table 1.
Contact the factory for other output voltage options.
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
MAX8884Y/MAX8884Z 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 MAX8884Y operates with a switching frequency of
2MHz and utilizes a 2.2µH inductor. The MAX8884Z
operates with a switching frequency of 4MHz and uti-
lizes a 1µH inductor. The higher switching frequency of
the MAX8884Z allows the use of physically smaller
inductors at the cost of lower efficiency. The lower
switching frequency of the MAX8884Y results in greater
efficiency at the cost of a physically larger inductor.
See the
Typical Operating Characteristics
for efficiency
graphs for both the MAX8884Y and the MAX8884Z.
The inductor’s DC current rating only needs to match the
maximum load of the application because the
MAX8884Y/MAX8884Z 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 50mΩto 150mΩrange. See
Table 2 for suggested inductors and manufacturers.
Output Capacitor Selection
For the DC-DC step-down converter, the output capacitor
CBUCK is required to keep the output voltage ripple small
and ensure regulation loop stability. CBUCK must have low
impedance at the switching frequency. Ceramic capaci-
tors 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 out-
put capacitance can be very low. A 2.2µF ceramic capaci-
tor 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
lighter than 10mA, it is sufficient to use a 0.1µF ceramic
capacitor for stable operation over the full temperature
range. For loads up to 200mA, an output capacitor of
1µF is sufficient for stable operation over the entire tem-
perature range. Operating the LDO at maximum rated
current the LDO1 and LDO2 requires a 2.2µF ceramic
capacitor. Using larger output capacitors reduces out-
put noise and improves load-transient response, stabili-
ty, and power-supply rejection.
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 4.7µF or more
to ensure stability at temperatures below -10°C. With X7R
or X5R dielectrics, 2.2µF is sufficient at all operating tem-
peratures. These regulators are optimized for ceramic
capacitors. Tantalum capacitors are not recommended.
Input Capacitor Selection
The input capacitor (CIN1) of the DC-DC step-down
converter reduces the current peaks drawn from the
battery or input power source and reduces switching
noise in the MAX8884Y/MAX8884Z. 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 ceramic
capacitor is recommended for most applications. For
optimum noise immunity and low input ripple, the input
capacitor value can be increased.
For the LDOs, use an input capacitance equal to the
value of the sum of the output capacitance of LDO1 and
LDO2. Larger input capacitor values and lower ESR pro-
vide better noise rejection and line transient response.
Note that some ceramic dielectrics exhibit large capaci-
tance and ESR variation with temperature. With dielectrics
such as Z5U and Y5V, it may be necessary to use two
times the sum of the output capacitor value 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.
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
12 ______________________________________________________________________________________
Table 2. Suggested Inductors
MANUFACTURER SERIES
INDUCTANCE
(µH)
ESR
()
CURRENT RATING
(mA)
DIMENSIONS
(mm)
CB2016T 1.0
2.2
0.09
0.13 510 2.0 x 1.6 x 1.8
= 5.8mm3
Taiyo Yuden
CB2518T 2.2
4.7
0.09
0.13
510
340 2.5 x 1.8 x 2.0 = 9mm3
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
FDK
MIPF2016 1.0
2.2 0.11 1100 2.0 x 1.6 x 1.0
= 3.2mm3
Murata LQH32C_53
1.0
2.2
0.06
0.10
1000
790
3.2 x 2.5 x 1.7
= 14mm3
D3010FB 1.0 0.20 1170 3.0 x 3.0 x 1.0
= 9mm3
D2812C 1.2
2.2
0.09
0.15
860
640
3.0 x 3.0 x 1.2
= 11mm3
D310F 1.5
2.2
0.13
0.17
1230
1080
3.6 x 3.6 x 1.0
= 13mm3
TOKO
D312C 1.5
2.2
0.10
0.12
1290
1140
3.6 x 3.6 x 1.2
= 16mm3
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
Sumida
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
Coilcraft LPO3310
1.0
1.5
2.2
0.07
0.10
0.13
1600
1400
1100
3.3 x 3.3 x 1.0
= 11mm3
ELC3FN 1.0
2.2
0.08
0.12
1400
1000
3.2 x 3.2 x 1.2
= 12mm3
Panasonic
ELL3GM 1.0
2.2
0.07
0.10
1400
1100
3.2 x 3.2 x 1.5
= 15mm3
Hitachi KSLI-252010
1.5
2.2
0.070
0.100
2200
1800
2.5 x 2.0 x 1.0
= 5mm3
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
______________________________________________________________________________________ 13
Reference Noise
Bypass Capacitor Selection
The REFBP capacitor reduces the output noise of LDO1
and LDO2. A value of 0.033µF is sufficient for most appli-
cations. This value can be increased up to 0.150µF with
some effect on the soft-start time of the LDOs. See the
Typical Operating Characteristics
for more information.
Do not use values greater than 0.150µF as this degrades
the performance of the internal reference voltage and has
a corresponding impact on all output voltages.
Ceramic capacitors with X5R or X7R dielectric are high-
ly recommended due to their small size, low ESR, and
small temperature coefficients. 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 recom-
mended value to achieve desired output noise perfor-
mance at temperatures below -10°C. Tantalum
capacitors are not recommended.
Thermal Considerations
In most applications, the MAX8884Y/MAX8884Z do not
dissipate much heat due to their high efficiency. But in
applications where the MAX8884Y/MAX8884Z run at high
ambient temperature with heavy loads, the heat dissipat-
ed may exceed the maximum junction temperature of the
part. If the junction temperature reaches approximately
+160°C, all power switches are turned off and LX and FB
become high impedance, and LDO1 and LDO2 are
pulled down to ground through an internal 100Ωresistor.
The MAX8884Y/MAX8884Z 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, PDISS, is:
where ηBUCK is the efficiency of the DC-DC step-down
converter, and PBUCK is the output power of the DC-DC
step-down converter.
The maximum allowed power dissipation, PMAX, is:
where (TJMAX - TA) is the temperature difference
between the MAX8884Y/MAX8884Z die junction and
the surrounding air, and 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.
Minimize the ground loop formed by CIN1, CBUCK, and
PGND. To do this, 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. Connect AGND and
PGND to the common ground plane. Figure 1 illustrates
an example PCB layout and routing scheme.
PTT
MAX
J MAX A
JA
=−
()
_
θ
PP BUCK IVV I VV
DISS BUCK LDO IN LDO LDO IN LDO
=−
⎛
⎝
⎜⎞
⎠
⎟+−+ −
1112 1 2 2 2
η()( )
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
14 ______________________________________________________________________________________
B3
A1 A2 A3 A4
B1 B2 B4
C1 C2 C3 C4
D1 D3 D4
BUCK
LDO1
4.0mm
3.8mm
LDO2
IN
GND
SEL
D2
LDO2_EN
BUCK_EN
LDO1_EN
PGND
LX
IN1A
FBNC2
IN1B
LDO1_ENLDO1
IN2
LDO2 BUCK_EN
SEL
LDO2_EN
NC1AGND
REFBP
CREFBP
CLDO2
CLDO1
CIN2
CIN1
LBUCK
CBUCK
Figure 1. Recommended PCB Layout
MAX8884Y/MAX8884Z
PWM LOGIC
STEP-DOWN
CURRENT LIMIT
PWM
ERROR AMP
LX
PGND
FB
IN1A
R1
R2
R6
R7
C2
C1
IN2
R8
R7
ERROR
AMP
ERROR
AMP
CURRENT LIMIT
REFBP
LDO1
LDO1_EN
R11
R10
CURRENT LIMIT
REFBP
LDO2
LDO2_EN
R9
R12
REF
REFBP
AGND
REF
LDO1_EN
LDO2_EN
SEL
IN1B
BUCK_EN
CONTROL
LOGIC
SEL
SEL
MAX8884Y
MAX8884Z
R3
Block Diagram
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
______________________________________________________________________________________ 15
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
16 ______________________________________________________________________________________
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
16 CSP R162A2+1 21-0226
2–4MHz
BUCK FB
REF
LDO1
CONTROL
LX
2.2µH (MAX8884Y)
1.0µH (MAX8884Z)
PGND
IN1A
SEL
REFBP
AGND
LDO1
LDO2
IN2
GPIO
GPIO
GPIO
BASEBAND
PROCESSOR
CAMERA MODULE
CORE
DIGITAL
ANALOG
1.2V
IN1B
LDO2_EN
LDO1_EN
BUCK_EN
4.7µF
Li+
BATTERY 2.2µF
2.2µF
2.2µF
2.2µF
0.033µF
MAX8884Y
MAX8884Z
LDO2
Typical Application Circuit
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.
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
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 ____________________
17
© 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 4/09 Initial release —
1 1/10 Added switching frequency TOCs and updated Step-Down Converter Control
Scheme section 8, 10