Rainbow Electronics MAX8668 User Manual
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-quiescent-current, low-noise LDOs operate down to 1.7V
supply voltage. The MAX8667/MAX8668 have individual enables for each output, maximizing flexibility.
The MAX8667/MAX8668 are available in the spacesaving, 3mm x 3mm, 16-pin thin QFN package.
Applications
Cell Phones/Smartphones
PDA and Palmtop Computers
Portable MP3 and DVD Players
Digital Cameras, Camcorders
PCMCIA Cards
Handheld Instruments
Features
♦ Tiny, Thin QFN 3mm x 3mm Package
♦ Individual Enables
♦ 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
♦ LDOs
300mA Guaranteed
Low 1.7V Minimum Supply Voltage
Low Output Noise
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
________________________________________________________________
Maxim Integrated Products
1
Pin Configuration
IN34
LX2
LX1
OUT2
OUT1
2.6V TO 5.5V
OUT3
OUT4
REF
GND
IN12
300mA
300mA
EN1
EN2
EN3
EN4
600mA
1.2A
PGND1 PGND2
10μF 4.7μF
4.7μF
4.7μF
0.01μF
2.2μH
2.2μH
2.2μF
2.2μF
MAX8667
Typical Operating Circuit
19-0784; Rev 0; 4/07
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.
Ordering Information continued at the end of data sheet.
Selector Guide appears at the end of data sheet.
Ordering Information
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.
PART PKG CODE TOP MARK
T1633-4 AEQ
T1633-4 AFI
T1633-4 AFM
T1633-4 AFN
MAX8667ETEAA+
MAX8667ETEAB+
MAX8667ETEAC+
MAX8667ETECQ+
TOP VIEW
13
PGND1
EN1
EN2
14
15
16
OUT1 (FB1)
( ) ARE FOR THE MAX8668
LX2
IN34
PGND2
8
7
6
5
4
OUT4
LX1
12 10 9
11
MAX8667
MAX8668
13
2
EN3
OUT3 IN12
THIN QFN
(3mm x 3mm)
OUT2 (FB2)
REF
GND
EN4
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
IN34
= V
IN12
= 3.6V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (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.
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 (V
IN34
+ 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 (V
IN12
+ 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.
IN34 Supply Range V
IN12 Supply Range MAX8668, V
IN12 Suppy Range MAX8667, V
Shutdown Supply Current,
I
IN12
No Load Supply Current,
I
IN12
UNDERVOLTAGE LOCKOUT
IN12 UVLO
IN34 UVLO
THERMAL SHUTDOWN
Threshold TA rising +160 °C
Hysteresis 15 °C
REFERENCE
Reference Bypass Output
Voltage
REF Supply Rejection 2.6V ≤ (V
LOGIC AND CONTROL INPUTS
EN_ Input Low Level
EN_ Input High Level
EN_ Input Leakage Current V
STEP-DOWN CONVERTERS
Minimum Adjustable Output
Voltage
PARAMETER CONDITIONS MIN TYP MAX UNITS
≥ V
IN12
IN34
≥ V
IN12
IN34
≥ V
IN12
IN34
V
+ I
+ I
IN34
IN34
= V
IN12
MAX8667ETEJS+, all regulators enabled 100 150 µA
V
rising 2.4 2.5 2.6 V
IN12
V
hysteresis 0.1 V
IN12
V
rising 1.5 1.6 1.7 V
IN34
V
hysteresis 0.1 V
IN34
1.7V ≤ V
2.6V ≤ V
1.7V ≤ V
2.6V ≤ V
= V
IN12
MAX8668 0.6 V
IN34
IN12
IN34
IN12
IN34
IN12
IN34
= 4.2V V
= V
≤ 5.5V
≤ 5.5V
≤ 5.5V
≤ 5.5V
= 5.5V
) ≤ 5.5V 0.15 mV/V
IN34
1.7 5.5 V
2.6 5.5 V
2.8 5.5 V
EN_
= 0V
TA = +25°C 1 µA
T
= +85°C 0.05 µA
A
0.591 0.600 0.609 V
1.44 V
TA = +25°C -1 +1
T
= +85°C 0.001
A
0.4 V
µA
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
_______________________________________________________________________________________ 3
Note 1: All devices are 100% production tested at TA= +25°C. Limits over the operating temperature range are guaranteed by design.
ELECTRICAL CHARACTERISTICS (continued)
(V
IN34
= V
IN12
= 3.6V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
Maximum Adjustable Output
Voltage
FB1, FB2 Regulation Voltage
OUT1, OUT2 Regulation Voltage
FB1, FB2 Line Regulation MAX8668, V
OUT1, OUT2 Line Regulation MAX8667, V
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 LX_ = 5.5V
Minimum On-Time 100 ns
Minimum Off-Time 50 ns
LDO REGULATORS
Supply Current Each LDO 20 µA
Output-Voltage Accuracy
Line Regulation V
Dropout Voltage V
Current Limit V
Soft-Start Ramp Time To 90% of final value 0.1 ms
Output Noise 100Hz to 100kHz, 30mA load, V
Power-Supply Rejection Ratio f < 1kHz, 30mA load 57 dB
Shutdown Output Resistance 1kΩ
TIMING (See Figure 2)
Power-On Time (t
Enable Time (tEN)
PARAMETER CONDITIONS MIN TYP MAX UNITS
MAX8668 3.3 V
MAX8668, no load,
V
falling
FB_
MAX8667ETEJS+, no load, V
falling
= 2.6V to 5.5V 0.01 %/V
IN12
= 2.8V to 5.5V 0.05 %/V
IN12
MAX8668, shutdown mode 0.1
MAX8668, V
pMOSFET switch (I
nMOSFET rectifier (valley current) 500 750 1000
pMOSFET switch (I
nMOSFET rectifier (valley current) 1200 1500 1800
pMOSFET switch, I
nMOSFET rectifier, I
pMOSFET switch, I
nMOSFET rectifier, I
)
1mA load, TA = +25°C -1.5 +1.5
1mA to 300mA load -3.0 +3.0
= 3.6V to 5.5V, 1mA load 0.003 %/V
IN34
= 1.8V, 300mA load 130 250 mV
IN34
, V
OUT3
PWRON
)
OUT1, OUT2 25
OUT3, OUT4 45
OUT1, OUT2 15
OUT3, OUT4 35
= 0.5V 0.01
FB1
) 700 900 1100
LIMP1
) 1333 1667 2000
LIMP2
= -400mA 0.3 0.6
LX1
= 400mA 0.3 0.6
LX1
= -400mA 0.12 0.27
LX2
= 400mA 0.12 0.27
LX2
90% of nominal value 375 420 465 mA
OUT4
TA = +25°C 0.588 0.600 0.612
T
= -40°C to +85°C 0.582 0.600 0.618
A
TA = +25°C 1.274 1.300 1.326
OUT_
T
= -40°C to +85°C 1.261 1.300 1.339
A
TA = +25°C -1 +1
T
= +85°C 0.1
A
OUT3
and V
= 2.8V 75 µV
OUT4
60 120 mA
V
V
µA
mA
mA
Ω
Ω
µA
%
RMS
µs
µs
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
4 _______________________________________________________________________________________
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, TA = +25°C, unless otherwise noted.)
OUT1 EFFICIENCY vs. LOAD CURRENT
(V
OUT1
= 1.2V)
MAX8667/88 toc01
LOAD CURRENT (mA)
EFFICIENCY (%)
101
10
20
30
40
50
60
70
80
90
0
0.1 1000100
ONLY OUT1 ENABLED
OUT2 EFFICIENCY vs. LOAD CURRENT
(V
OUT2
= 1.8V)
MAX8667/88 toc02
LOAD CURRENT (mA)
EFFICIENCY (%)
1000100101
10
20
30
40
50
60
70
80
90
0
0.1 10000
ONLY OUT2 ENABLED
0.80
0.90
0.85
1.05
1.00
0.95
1.20
1.15
1.10
1.25
0 200100 300 400 500 600
OUT1 LOAD REGULATION
MAX8667/88 toc03
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
1.20
1.40
1.30
1.60
1.50
1.80
1.70
1.90
0 400 600200 800 1000 1200
OUT2 LOAD REGULATION
MAX8667/88 toc04
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
1.00
1.05
1.10
1.15
1.20
1.25
1.30
1.35
1.40
2.5 3.53.0 4.0 4.5 5.0 5.5
OUT1 OUTPUT VOLTAGE
vs. INPUT VOLTAGE (600mA LOAD)
MAX8667/88 toc05
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
1.60
1.65
1.70
1.75
1.80
1.85
1.90
1.95
2.00
2.5 3.53.0 4.0 4.5 5.0 5.5
OUT2 OUTPUT VOLTAGE
vs. INPUT VOLTAGE (1200mA LOAD)
MAX8667/88 toc06
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
0
1000
500
2000
1500
3000
2500
3500
0 600 900300 1200 1500 1800
SWITCHING FREQUENCY
vs. LOAD CURRENT
MAX8667/88 toc07
LOAD CURRENT (mA)
SWITCHING FREQUENCY (kHz)
OUT2
OUT1
0
20
40
60
80
100
120
1.5 2.52.0 3.0 3.5 4.0 4.5 5.0 5.5
NO-LOAD SUPPLY CURRENT vs. SUPPLY
VOLTAGE ALL REGULATOR ENABLED
MAX8667/88 toc08
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (μA)
SUPPLY VOLTAGE
RISING
SUPPLY VOLTAGE
FALLING
0
20
40
60
80
100
120
1.5 2.52.0 3.0 3.5 4.0 4.5 5.0 5.5
NO-LOAD SUPPLY CURRENT
vs. SUPPLY VOLTAGE OUT1 AND OUT2 ONLY
MAX8667/88 toc09
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (μA)
SUPPLY VOLTAGE
RISING
SUPPLY VOLTAGE
FALLING
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
_______________________________________________________________________________________
5
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, TA = +25°C, unless otherwise noted.)
10μs/div
OUT1 LOAD TRANSIENT
V
OUT1
I
OUT1
100mV/div
(AC-COUPLED)
200mA/div
200mA/div
MAX8667/88 toc16
I
L1
300mA
10mA
10mA
NO-LOAD SUPPLY CURRENT vs. SUPPLY
VOLTAGE OUT3 AND OUT4 ONLY
120
100
80
(μA)
IN34
I
V
VOLTAGE
IN34
60
FALLING
40
V
VOLTAGE
20
0
012345
IN34
RISING
SUPPLY VOLTAGE (V)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
1000
900
800
700
600
500
400
300
SUPPLY CURRENT (mA)
200
100
0
2.5 3.53.0 4.0 4.5 5.0 5.5
V
= 5.5V
IN12
SUPPLY VOLTAGE (V)
3.00
2.95
2.90
MAX8667/88 toc10
2.85
2.80
2.75
2.70
OUTPUT VOLTAGE (V)
2.65
2.60
2.55
2.50
IN12 = IN34
2.4Ω LOAD ON OUT1
3.6Ω LOAD ON OUT2
NO LOAD ON OUT3
NO LOAD ON OUT4
OUT3 OUTPUT VOLTAGE
vs. INPUT VOLTAGE (300mA LOAD)
2.5 3.53.0 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
EN1/EN2/
I
IN12
EN3/EN4
V
OUT1
V
OUT2
V
OUT3
V
OUT4
+ I
IN34
I
L1
I
L2
MAX8667/88 toc13
OUT3 DROPOUT VOLTAGE
vs. LOAD CURRENT
80
70
MAX8667/88 toc11
60
50
40
30
DROPOUT VOLTAGE (mV)
20
10
0
0 100 200 300
LOAD CURRENT (mA)
ENABLE WAVEFORMS
40
μs/div
MAX8667/88 toc14
5V/div
2V/div
2V/div
2V/div
2V/div
2A/div
2A/div
2A/div
MAX8667/88 toc12
SHUTDOWN WAVEFORMS
EN1/EN2/
EN3/EN4
V
OUT1
V
OUT2
V
OUT3
V
OUT4
40μs/div
MAX8667/88 toc15
5V/div
1V/div
1V/div
1V/div
1V/div
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
6 _______________________________________________________________________________________
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, TA = +25°C, unless otherwise noted.)
OUT2 LOAD TRANSIENT
MAX8667/88 toc17
OUT3 LOAD TRANSIENT
MAX8667/88 toc18
V
OUT2
600mA
I
OUT2
I
L2
10μs/div
10mA10mA
V
OUT4
I
OUT4
OUT4 LOAD TRANSIENT
300mA
0mA
10μs/div
MAX8667/88 toc19
0mA
200mV/div
(AC-COUPLED)
500mA/div
500mA/div
50mV/div
(AC-COUPLED)
200mA/div
V
I
OUT3
OUT3
V
300mA
0mA
OUT1 LIGHT-LOAD SWITCHING
WAVEFORMS
OUT1
V
LX1
I
L1
500μA LOAD
10μs/div
10μs/div
0mA
MAX8667/88 toc20
50mV/div
(AC-COUPLED)
200mA/div
20mV/div
2V/div
100mA/div
V
OUT2 LIGHT-LOAD SWITCHING
WAVEFORMS
OUT2
V
LX2
I
L2
500μA LOAD
40μs/div
MAX8667/88 toc21
20mV/div
2V/div
500mA/div
V
OUT1 HEAVY-LOAD SWITCHING
WAVEFORMS
OUT1
V
LX1
I
L1
500μA LOAD
MAX8667/88 toc22
400ns/div
20mV/div
2V/div
500mA/div
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