19-4504; Rev 4; 6/11
KIT
ATION
EVALU
BLE
AVAILA
1.8A Step-Down Regulator with
Remote Sense in 2mm x 2mm WLP
General Description
Features
o
1.8A Guaranteed Output Current
o
I
2
C Programmable V
OUT
(750mV to 1.38V in 10mV
Steps)
o
Operates from 2.5V to 5.5V Input Supply
o
On-Chip FET and Synchronous Rectifier
o
Fixed 3.25MHz PWM Switching Frequency
o
Synchronizes to 13MHz, 19.2MHz, or 26MHz
System Clock when Available
o
Small 1.0µH Inductor
o
Initial Accuracy 0.5% at 1.25V Output
o
2% Output Accuracy Over Load, Line, and
Temperature
o
Power-Save Mode Increases Light Load Efficiency
o
Overvoltage and Overcurrent Protection
o
Thermal Shutdown Protection
o
400kHz I
2
C Interface
o
< 1µA Shutdown Current
o
16-Bump, 2mm x 2mm WLP Package
MAX8649/MAX8649A
The MAX8649/MAX8649A high-efficiency DC-to-DC step-
down switching regulators deliver up to 1.8A of output cur-
rent. The device operates from a 2.5V to 5.5V input
voltage range, making it future proof for next-generation
battery technologies. The output voltage is I
2
C program-
mable from 0.75V to 1.38V. Remote sense ensures pre-
cise DC regulation at the load. Total output error is less
than 2% over load, line, and temperature.
The ICs operate at a 3.25MHz fixed frequency. The high
operating frequency minimizes the size of external com-
ponents. The switching frequency of the converter can be
synchronized to the master clock of the application. When
synchronizing to an external clock, the ICs measure the
frequency of the external clock to ensure that the clock is
stable before changing the switching frequency to the
external clock frequency.
An on-board DAC allows adjustment of the output volt-
age in 10mV steps. The output voltage can be pro-
grammed directly through the I
2
C interface, or by
preloading a set of on-board registers and using the
two VID logic signals to select the appropriate register.
Other features include internal soft-start control circuitry
to reduce inrush current, output overvoltage, overcur-
rent, and overtemperature protection.
The ICs feature different I
2
C addresses so that devices
may be used in a system. For a 2.5A version of this
device, refer to the MAX8952 data sheet.
Ordering Information
PART
MAX8649EWE+T
PIN-PACKAGE
16 WLP (0.5mm pitch)
I
2
C ADDRESS
(WRITE/READ)
0xC0/0xC1
0xC4/0xC5
MAX8649AEWE+T
16 WLP (0.5mm pitch)
Applications
Cell Phones and Smartphones
PDAs and MP3 Players
+Denotes
a lead(Pb)-free/RoHS-compliant package.
Note:
All devices operate over the -40°C to +85°C temperature
range.
Bump Configuration
TOP VIEW
(BUMPS ON BOTTOM)
1.8V TO
3.6V
Typical Operating Circuit
2.5V TO
5.5V
+
IN1
A1
SNS+
B1
SNS-
C1
V
DD
D1
AGND
A2
EN
B2
VID0
C2
SDA
D2
VID1
A3
LX
B3
PGND
C3
SCL
D3
IN2
A4
MAX8649
MAX8649A
IN2
V
DD
0.1μF
1μH
SCL
11Ω
SDA
IN1
LX
10μF
PGND
0.1μF
10μF
0.1μF
V
OUT
(0.75V TO
1.38V)
LX
B4
PGND
C4
SYNC
D4
2.5V TO
5.5V
2.2μF
0.1μF
FSYNC
EN
VID0
VID1
AGND
SNS-
SNS+
CPU
WLP 0.5mm PITCH
________________________________________________________________
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.
1.8A Step-Down Regulator with
Remote Sense in 2mm x 2mm WLP
MAX8649/MAX8649A
ABSOLUTE MAXIMUM RATINGS
IN1, IN2 to AGND ..................................................-0.3V to +6.0V
V
DD
to AGND.........................................................-0.3V to +4.0V
LX, SNS+, VID0, VID1, EN to AGND..........-0.3V to (V
IN1
+ 0.3V)
SCL, SDA, SYNC to AGND.........................-0.3V to (V
DD
+ 0.3V)
PGND, SNS- to AGND...........................................-0.3V to +0.3V
RMS LX Current ..............................................................1800mA
Continuous Power Dissipation (T
A
= +70°C)
16-Bump WLP 0.5mm Pitch
(derate 13mW/°C above +70°C) ............................1040mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Soldering Temperature (reflow) .......................................+260°C
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.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
WLP
Junction to Ambient Thermal Resistance (θ
JA
)............76°C/W
Note 1:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to
www.maxim-ic.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(V
IN1
= V
IN2
= 3.6V, V
AGND
= V
PGND
= 0V, V
DD
= 1.8V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at
T
A
= +25°C.) (Note 2)
PARAMETER
IN1, IN2 Operating Range
V
DD
Operating Range
V
DD
Undervoltage Lockout
(UVLO) Threshold
V
DD
UVLO Hysteresis
IN_ Undervoltage Lockout
(UVLO) Threshold
IN_ UVLO Hysteresis
V
DD
Shutdown Supply Current
IN1, IN2 Shutdown Supply
Current
IN1, IN2 Standby Supply Current
V
IN1
= V
IN2
= 5.5V,
EN = V
DD
= AGND
V
IN1
= V
IN2
= 5.5V,
EN = V
DD
= AGND
V
IN1
= V
IN2
= 5.5V, SCL = SDA =
V
DD
, EN = AGND, I
2
C ready
V
IN1
= V
IN2
= V
DD
= 3.6V,
SCL = SDA = V
DD
, EN = AGND,
I
2
C ready
T
A
= +25°C
T
A
= +85°C
T
A
= +25°C
T
A
= +85°C
T
A
= +25°C
T
A
= +85°C
T
A
= +25°C
T
A
= +85°C
EN, VID0, VID1
SYNC, SCL, SDA
EN, VID0, VID1
SYNC, SCL, SDA
T
A
= +25°C
T
A
= +85°C
-1
0.01
0.01
1.4
0.7 x V
DD
0.4
0.3 x V
DD
+1
V
IN
falling
2.10
V
DD
falling
CONDITIONS
MIN
2.5
1.8
0.54
0.865
50
2.15
70
0.01
0.01
0.25
0.25
0.35
0.35
0.02
0.02
1
µA
1
1
1
2.20
TYP
MAX
5.5
3.6
1.35
UNITS
V
V
V
mV
V
mV
µA
µA
µA
V
DD
Standby Supply Current
LOGIC INTERFACE
Logic Input High Voltage (V
IH
)
Logic Input Low Voltage (V
IL
)
SDA, SCL, SYNC Logic Input
Current
V
IN1
= V
IN2
= 2.5V to 5.5V,
V
DD
= 1.8V to 3.6V
V
IN1
= V
IN2
= 2.5V to 5.5V,
V
DD
= 1.8V to 3.6V
V
IL
= 0V or V
IH
= 3.6V,
EN = AGND
V
V
µA
2
_______________________________________________________________________________________
1.8A Step-Down Regulator with
Remote Sense in 2mm x 2mm WLP
ELECTRICAL CHARACTERISTICS (continued)
(V
IN1
= V
IN2
= 3.6V, V
AGND
= V
PGND
= 0V, V
DD
= 1.8V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
=
+25°C.) (Note 2)
PARAMETER
VID0, VID1, EN Logic Input
Pulldown Resistor
I
2
C INTERFACE
SDA Output Low Voltage
I C Clock Frequency
Bus-Free Time Between START
and STOP
Hold Time Repeated START
Condition
SCL Low Period
SCL High Period
Setup Time Repeated START
Condition
SDA Hold Time
SDA Setup Time
Setup Time for STOP Condition
IN1 + IN2
Supply Current
Minimum Output Capacitance
Required for Stability
OUT Voltage Range
Output Overvoltage Protection
t
BUF
t
HD_STA
t
LOW
t
HIGH
t
SU_STA
t
HD_DAT
t
SU_DAT
t
SU_STO
OPERATION_MODE_ = 0, V
OUT
= 1.27V, no switching
OPERATION_MODE_ = 1, V
OUT
= 1.27V, f
sw
= 3.25MHz
V
OUT
= 0.75V to 1.38V,
I
OUT
= 0 to 1.8A
10mV steps
Rising, 50mV hysteresis (typ)
0.750
1.65
1.8
1.3
0.6
1.3
0.6
0.6
0
0.1
0.6
0.1
0.2
0.2
0.1
-0.01
0.05
0.1
54
9
10
1.380
1.9
70
2
MAX8649/MAX8649A
CONDITIONS
Controlled by I
2
C command:
VID0_PD = 1
VID1_PD = 1
EN_PD = 1
I
SDA
= 3mA
MIN
TYP
MAX
UNITS
200
320
450
kΩ
0.03
0.4
400
V
kHz
µs
µs
µs
µs
µs
µs
µs
µs
µA
mA
µF
V
V
STEP-DOWN DC-DC REGULATOR
_______________________________________________________________________________________
3
1.8A Step-Down Regulator with
Remote Sense in 2mm x 2mm WLP
MAX8649/MAX8649A
ELECTRICAL CHARACTERISTICS (continued)
(V
IN1
= V
IN2
= 3.6V, V
AGND
= V
PGND
= 0V, V
DD
= 1.8V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
=
+25°C.) (Note 2)
PARAMETER
CONDITIONS
No load, V
IN_
= 2.5V to 5.5V, V
OUT
= 1.27V
OPERATION_MODE_ = 1
OUT Voltage Accuracy
I
OUT
= no load, V
IN_
= 2.5V to 5.5V, V
OUT
= 0.75V,
OPERATION_MODE_ = 1
I
OUT
= no load, V
IN_
= 2.5V to 5.5V, V
OUT
= 1.38V,
OPERATION_MODE_ = 1
Load Regulation
R
L
is the resistance from LX to SNS+ (output)
RAMP[2:0] = 000
RAMP[2:0] = 001
RAMP[2:0] = 010
RAMP Timer
RAMP[2:0] = 011
RAMP[2:0] = 100
RAMP[2:0] = 101
RAMP[2:0] = 110
RAMP[2:0] = 111
Peak Current Limit
(p-Channel MOSFET)
Valley Current Limit
(n-Channel MOSFET)
Negative Current Limit
(n-Channel MOSFET)
n-Channel Zero-Crossing
Threshold
LX pFET On-Resistance
LX nFET On-Resistance
LX Leakage
IN2 to LX, I
LX
= -200mA
OPERATION_MODE = 0
LX to PGND, I
LX
= 200mA
V
LX
= 5.5V or 0V
Internal oscillator, PWM
Internal oscillator, power-save mode before entering
PWM mode
Operating Frequency
13MHz option
19.2MHz option
26MHz option
T
A
= +25°C
T
A
= +85°C
2.82
2.43
-1
PWM and hysteretic mode
Hysteretic mode
PWM mode
2.3
1.8
2.0
MIN
-0.5
-1.0
-0.5
R
L
/25
32.50
16.25
8.125
4.063
2.031
1.016
0.508
0.254
2.8
2.4
2.5
50
0.08
0.06
0.03
0.05
3.25
3.25
f
SYNC
/4
f
SYNC
/6
f
SYNC
/8
3.56
4.06
MHz
0.16
0.12
+1
3.2
3.0
3.0
A
A
A
mA
Ω
Ω
µA
mV/µs
TYP
MAX
+0.5
+1.0
+0.5
V/A
%
UNITS
4
_______________________________________________________________________________________
1.8A Step-Down Regulator with
Remote Sense in 2mm x 2mm WLP
ELECTRICAL CHARACTERISTICS (continued)
(V
IN1
= V
IN2
= 3.6V, V
AGND
= V
PGND
= 0V, V
DD
= 1.8V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
=
+25°C.) (Note 2)
PARAMETER
Minimum Duty Cycle
Maximum Duty Cycle
Minimum On- and Off-Time
OUT Discharge Resistance
SNS+, SNS- Input Impedance
Time Delay from PWM
to Power-Save Mode
Time Delay from Power-Save
Mode to PWM
SYNCHRONIZATION (SYNC)
SYNC = 00 default
SYNC Capture Range
SYNC Pulse Width
PROTECTION CIRCUITS
Thermal-Shutdown Hysteresis
Thermal Shutdown
20
+160
°C
°C
SYNC = 1X default
SYNC = 01 default
18.9
14.2
9.5
26.0
19.2
13.0
13
38.0
28.5
19.0
ns
MHz
During shutdown or UVLO, from SNS+ to PGND
V
OUT
= 0.75V (OUT_MODEx [5:0] = 0b000000)
Time required for error amplifier to stabilize before
switching mode
Time required for error amplifier to stabilize before
switching mode
400
CONDITIONS
Forced PWM mode only, minimum duty cycle in
(OPERATION_MODE_ = 1) = 0%
60
30
40
650
600
70
140
850
50
MIN
TYP
MAX
16
UNITS
%
%
ns
Ω
kΩ
µs
µs
MAX8649/MAX8649A
Note 2:
All devices are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed by
design.
_______________________________________________________________________________________
5
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