19-0784; Rev 1; 7/07
KIT
ATION
EVALU
E
BL
AVAILA
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
General Description
The MAX8667/MAX8668 dual step-down converters
with dual low-dropout (LDO) linear regulators are
intended to power low-voltage microprocessors or
DSPs in portable devices. They feature high efficiency
with small external component size. The step-down
converters are adjustable from 0.6V to 3.3V (MAX8668)
or factory preset (MAX8667) with guaranteed output
current of 600mA for OUT1 and 1200mA for OUT2. The
1.5MHz hysteretic-PWM control scheme allows for tiny
external components and reduces no-load operating
current to 100µA with all outputs enabled. Dual low-qui-
escent-current, low-noise LDOs operate down to 1.7V
supply voltage. The MAX8667/MAX8668 have individ-
ual enables for each output, maximizing flexibility.
The MAX8667/MAX8668 are available in the space-
saving, 3mm x 3mm, 16-pin thin QFN package.
Features
o
Tiny, Thin QFN 3mm x 3mm Package
o
Individual Enables
o
Step-Down Converters
600mA Guaranteed Output Current on OUT1
1200mA Guaranteed Output Current on OUT2
Tiny Size 2.2µH Chip Inductor (0805)
Output Voltage from 0.6V to 3.3V (MAX8668)
Ultra-Fast Line and Load Transients
Low 25µA Supply Current Each
o
LDOs
300mA Guaranteed
Low 1.7V Minimum Supply Voltage
Low Output Noise
MAX8667/MAX8668
Ordering Information
PART
MAX8667ETEAA+
MAX8667ETEAB+
MAX8667ETEAC+
MAX8667ETECQ+
PKG CODE
T1633-4
T1633-4
T1633-4
T1633-4
TOP MARK
AEQ
AFI
AFM
AFN
Applications
Cell Phones/Smartphones
PDA and Palmtop Computers
Portable MP3 and DVD Players
Digital Cameras, Camcorders
PCMCIA Cards
Handheld Instruments
Note:
All MAX8667/MAX8668 parts are in a 16-pin, thin QFN,
3mm x 3mm package and operate in the -40°C to +85°C
extended temperature range.
+Denotes
a lead-free package.
Ordering Information continued at the end of data sheet.
Selector Guide appears at the end of data sheet.
Typical Operating Circuit
IN12
2.6V TO 5.5V
10µF
IN12
EN1
EN2
REF
0.01µF
GND
IN34
EN3
EN4
OUT3
300mA
OUT4
4.7µF
4.7µF
OUT1 (FB1) 14
EN1 15
EN2 16
2.2µH
LX1
2.2µF
OUT1
PGND1
LX2
OUT2
PGND2
2.2µF
1.2A
1
EN3
2
OUT3
300mA
PGND1 13
4.7µF
LX1
Pin Configuration
TOP VIEW
PGND2
9
8
7
OUT2 (FB2)
REF
GND
EN4
6
5
3
IN34
4
OUT4
12
11
10
MAX8667
MAX8668
MAX8667
600mA
2.2µH
THIN QFN
(3mm x 3mm)
( ) ARE FOR THE MAX8668
________________________________________________________________
Maxim Integrated Products
LX2
1
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.
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
MAX8667/MAX8668
ABSOLUTE MAXIMUM RATINGS
IN12, IN34, FB1, FB2, EN1, EN2, EN3, EN4, OUT1,
OUT2, REF to GND............................................-0.3V to +6.0V
OUT3,
OUT4 to GND.....-0.3V to the lesser of + 6V or (VIN34 + 0.3V)
PGND1, PGND2 to GND .......................................-0.3V to +0.3V
LX1, LX2 Current ..........................................................1.5A RMS
LX1, LX2 to GND (Note 1) .......................-0.3V to (VIN12 + 0.3V)
Continuous Power Dissipation (TA = +70°C)
16-Pin, 3mm x 3mm Thin QFN
(derate 20.8mW/°C above +70°C) .............................1667mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ..................................................... +150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1:
LX_ has internal clamp diodes to GND and IN12. Applications that forward bias these diodes should take care not to exceed
the IC’s package-dissipation limits.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
IN34
= V
IN12
= 3.6V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
IN34 Supply Range
IN12 Supply Range
IN12 Suppy Range
Shutdown Supply Current,
I
IN12
+ I
IN34
No Load Supply Current,
I
IN12
+ I
IN34
UNDERVOLTAGE LOCKOUT
IN12 UVLO
IN34 UVLO
THERMAL SHUTDOWN
Threshold
Hysteresis
REFERENCE
Reference Bypass Output
Voltage
REF Supply Rejection
LOGIC AND CONTROL INPUTS
EN_ Input Low Level
EN_ Input High Level
EN_ Input Leakage Current
STEP-DOWN CONVERTERS
Minimum Adjustable Output
Voltage
MAX8668
0.6
V
1.7V
≤
V
IN34
≤
5.5V
2.6V
≤
V
IN12
≤
5.5V
1.7V
≤
V
IN34
≤
5.5V
2.6V
≤
V
IN12
≤
5.5V
V
IN12
= V
IN34
= 5.5V
T
A
= +25°C
T
A
= +85°C
1.44
-1
0.001
+1
0.4
V
V
µA
2.6V
≤
(V
IN12
= V
IN34
)
≤
5.5V
0.591
0.600
0.15
0.609
V
mV/V
T
A
rising
+160
15
°C
°C
V
IN12
rising
V
IN12
hysteresis
V
IN34
rising
V
IN34
hysteresis
1.5
2.4
2.5
0.1
1.6
0.1
1.7
2.6
V
V
V
V
V
IN12
≥
V
IN34
MAX8668, V
IN12
≥
V
IN34
MAX8667, V
IN12
≥
V
IN34
V
IN12
= V
IN34
= 4.2V V
EN_
= 0V
T
A
= +25°C
T
A
= +85°C
0.05
100
150
CONDITIONS
MIN
1.7
2.6
2.8
TYP
MAX
5.5
5.5
5.5
1
UNITS
V
V
V
µA
µA
µA
MAX8667ETEJS+, all regulators enabled
2
_______________________________________________________________________________________
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
ELECTRICAL CHARACTERISTICS (continued)
(V
IN34
= V
IN12
= 3.6V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Maximum Adjustable Output
Voltage
FB1, FB2 Regulation Voltage
OUT1, OUT2 Regulation Voltage
FB1, FB2 Line Regulation
OUT1, OUT2 Line Regulation
FB1, FB2 Bias Current
OUT1 Current Limit
OUT2 Current Limit
OUT1 On-Resistance
OUT2 On-Resistance
Rectifier-Off Current Threshold
(I
LXOFF
)
LX Leakage Current
Minimum On-Time
Minimum Off-Time
LDO REGULATORS
Supply Current
Output-Voltage Accuracy
Line Regulation
Dropout Voltage
Current Limit
Soft-Start Ramp Time
Output Noise
Power-Supply Rejection Ratio
Shutdown Output Resistance
TIMING (See Figure 2)
Power-On Time (t
PWRON
)
Enable Time (t
EN
)
OUT1, OUT2
OUT3, OUT4
OUT1, OUT2
OUT3, OUT4
25
45
15
35
µs
µs
Each LDO
1mA load, T
A
= +25°C
1mA to 300mA load
V
IN34
= 3.6V to 5.5V, 1mA load
V
IN34
= 1.8V, 300mA load
V
OUT3
, V
OUT4
90% of nominal value
To 90% of final value
100Hz to 100kHz, 30mA load, V
OUT3
and V
OUT4
= 2.8V
f < 1kHz, 30mA load
375
-1.5
-3.0
0.003
130
420
0.1
75
57
1
250
465
20
+1.5
+3.0
µA
%
%/V
mV
mA
ms
µV
RMS
dB
kΩ
LX_ = 5.5V
T
A
= +25°C
T
A
= +85°C
-1
0.1
100
50
MAX8668
MAX8668, no load,
V
FB_
falling
MAX8667ETEJS+, no load, V
OUT_
falling
MAX8668, V
IN12
= 2.6V to 5.5V
MAX8667, V
IN12
= 2.8V to 5.5V
MAX8668, shutdown mode
MAX8668, V
FB1
= 0.5V
pMOSFET switch (I
LIMP1
)
nMOSFET rectifier (valley current)
pMOSFET switch (I
LIMP2
)
nMOSFET rectifier (valley current)
pMOSFET switch, I
LX1
= -400mA
nMOSFET rectifier, I
LX1
= 400mA
pMOSFET switch, I
LX2
= -400mA
nMOSFET rectifier, I
LX2
= 400mA
700
500
1333
1200
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
0.588
0.582
1.274
1.261
CONDITIONS
MIN
TYP
3.3
0.600
0.600
1.300
1.300
0.01
0.05
0.1
0.01
900
750
1667
1500
0.3
0.3
0.12
0.12
60
1100
1000
2000
1800
0.6
0.6
0.27
0.27
120
+1
0.612
0.618
1.326
1.339
MAX
UNITS
V
V
V
%/V
%/V
µA
mA
mA
Ω
Ω
mA
µA
ns
ns
MAX8667/MAX8668
Note 1:
All devices are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed by design.
_______________________________________________________________________________________
3
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
MAX8667/MAX8668
Typical Operating Characteristics
(V
IN12
= V
IN34
= 3.6V, circuit of Figure 4, V
OUT1
= 1.2V, V
OUT2
= 1.8V, V
OUT3
= 2.8V, V
OUT4
= 2.8V, T
A
= +25°C, unless otherwise noted.)
OUT1 EFFICIENCY vs. LOAD CURRENT
(V
OUT1
= 1.2V)
MAX8667/88 toc01
OUT2 EFFICIENCY vs. LOAD CURRENT
(V
OUT2
= 1.8V)
MAX8667/88 toc02
OUT1 LOAD REGULATION
1.20
1.15
OUTPUT VOLTAGE (V)
1.10
1.05
1.00
0.95
0.90
0.85
MAX8667/88 toc03
90
80
70
EFFICIENCY (%)
60
50
40
30
20
10
ONLY OUT1 ENABLED
0
0.1
1
10
100
90
80
70
EFFICIENCY (%)
60
50
40
30
20
10
0
ONLY OUT2 ENABLED
0.1
1
10
100
1000
1.25
0.80
0
100
200
300
400
500
600
LOAD CURRENT (mA)
1000
10000
LOAD CURRENT (mA)
LOAD CURRENT (mA)
OUT2 LOAD REGULATION
MAX8667/88 toc04
OUT1 OUTPUT VOLTAGE
vs. INPUT VOLTAGE (600mA LOAD)
MAX8667/88 toc05
OUT2 OUTPUT VOLTAGE
vs. INPUT VOLTAGE (1200mA LOAD)
1.95
OUTPUT VOLTAGE (V)
1.90
1.85
1.80
1.75
1.70
1.65
1.60
MAX8667/88 toc06
1.90
1.80
OUTPUT VOLTAGE (V)
1.70
1.60
1.50
1.40
1.30
1.20
0
200
400
600
800
1000
1.40
1.35
OUTPUT VOLTAGE (V)
1.30
1.25
1.20
1.15
1.10
1.05
1.00
2.00
1200
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
SWITCHING FREQUENCY
vs. LOAD CURRENT
MAX8667/88 toc07
NO-LOAD SUPPLY CURRENT vs. SUPPLY
VOLTAGE ALL REGULATOR ENABLED
MAX8667/88 toc08
NO-LOAD SUPPLY CURRENT
vs. SUPPLY VOLTAGE OUT1 AND OUT2 ONLY
MAX8667/88 toc09
3500
3000
2500
2000
1500
1000
500
0
0
300
600
900
1200
1500
OUT1
OUT2
120
100
SUPPLY CURRENT (µA)
80
60
40
20
0
SUPPLY VOLTAGE
RISING
120
100
SUPPLY CURRENT (µA)
80
60
40
20
0
SUPPLY VOLTAGE
RISING
SUPPLY VOLTAGE
FALLING
SWITCHING FREQUENCY (kHz)
SUPPLY VOLTAGE
FALLING
1800
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
LOAD CURRENT (mA)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
4
_______________________________________________________________________________________
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
Typical Operating Characteristics (continued)
(V
IN12
= V
IN34
= 3.6V, circuit of Figure 4, V
OUT1
= 1.2V, V
OUT2
= 1.8V, V
OUT3
= 2.8V, V
OUT4
= 2.8V, T
A
= +25°C, unless otherwise noted.)
NO-LOAD SUPPLY CURRENT vs. SUPPLY
VOLTAGE OUT3 AND OUT4 ONLY
MAX8667/88 toc10
MAX8667/MAX8668
OUT3 OUTPUT VOLTAGE
vs. INPUT VOLTAGE (300mA LOAD)
2.95
2.90
OUTPUT VOLTAGE (V)
2.85
2.80
2.75
2.70
2.65
2.60
2.55
2.50
MAX8667/88 toc11
OUT3 DROPOUT VOLTAGE
vs. LOAD CURRENT
70
DROPOUT VOLTAGE (mV)
60
50
40
30
20
10
0
0
100
200
300
MAX8667/88 toc12
120
V
IN12
= 5.5V
100
80
I
IN34
(µA)
60
40
20
0
0
1
2
3
4
5
SUPPLY VOLTAGE (V)
V
IN34
VOLTAGE
RISING
V
IN34
VOLTAGE
FALLING
3.00
80
2.5
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
900
800
SUPPLY CURRENT (mA)
700
600
500
400
300
200
100
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
IN12 = IN34
2.4Ω LOAD ON OUT1
3.6Ω LOAD ON OUT2
NO LOAD ON OUT3
NO LOAD ON OUT4
MAX8667/88 toc13
ENABLE WAVEFORMS
MAX8667/88 toc14
1000
EN1/EN2/
EN3/EN4
V
OUT1
V
OUT2
V
OUT3
V
OUT4
I
L1
I
L2
I
IN12
+ I
IN34
40µs/div
5V/div
2V/div
2V/div
2V/div
2V/div
2A/div
2A/div
2A/div
SHUTDOWN WAVEFORMS
MAX8667/88 toc15
OUT1 LOAD TRANSIENT
MAX8667/88 toc16
EN1/EN2/
EN3/EN4
V
OUT1
V
OUT2
V
OUT3
V
OUT4
5V/div
V
OUT1
300mA
100mV/div
(AC-COUPLED)
1V/div
1V/div
I
OUT1
10mA
10mA
200mA/div
1V/div
I
L1
1V/div
10µs/div
200mA/div
40µs/div
_______________________________________________________________________________________
5
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