Maxim MAX8667ETECQ+ 1.5mhz dual step-down dc-dc converters with dual ldos and individual enable Datasheet

19-0784; Rev 1; 7/07
KIT
ATION
EVALU
E
L
B
AVAILA
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
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
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
Ordering Information
PART
PKG CODE
TOP MARK
MAX8667ETEAA+
T1633-4
AEQ
MAX8667ETEAB+
T1633-4
AFI
MAX8667ETEAC+
T1633-4
AFM
MAX8667ETECQ+
T1633-4
AFN
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.
Digital Cameras, Camcorders
PCMCIA Cards
+Denotes a lead-free package.
Handheld Instruments
Ordering Information continued at the end of data sheet.
Selector Guide appears at the end of data sheet.
Pin Configuration
EN3
EN2
REF
OUT3
EN4
2.2µF
OUT2 (FB2)
300mA
OUT1 (FB1) 14
7
REF
6
GND
5
EN4
4.7µF
MAX8667
MAX8668
EN1 15
EN2 16
2.2µH
1.2A
LX2
OUT2
PGND2
1
EN3
OUT1
PGND1
9
8
4.7µF
2.2µH
LX1
10
PGND1 13
MAX8667
600mA
11
300mA
OUT4
GND
12
2.2µF
2
3
4
OUT4
0.01µF
PGND2
4.7µF
IN34
IN34
IN12
EN1
OUT3
10µF
LX2
TOP VIEW
IN12
2.6V TO 5.5V
LX1
Typical Operating Circuit
THIN QFN
(3mm x 3mm)
( ) ARE FOR THE MAX8668
________________________________________________________________ Maxim Integrated Products
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
MAX8667/MAX8668
General Description
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
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
(VIN34 = VIN12 = 3.6V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
MAX
UNITS
VIN12 ≥ VIN34
1.7
5.5
V
IN12 Supply Range
MAX8668, VIN12 ≥ VIN34
2.6
5.5
V
IN12 Suppy Range
MAX8667, VIN12 ≥ VIN34
2.8
5.5
V
1
µA
IN34 Supply Range
CONDITIONS
MIN
TYP
TA = +25°C
Shutdown Supply Current,
IIN12 + IIN34
VIN12 = VIN34 = 4.2V VEN_ = 0V
No Load Supply Current,
IIN12 + IIN34
MAX8667ETEJS+, all regulators enabled
TA = +85°C
0.05
µA
100
150
µA
2.5
2.6
V
1.7
V
UNDERVOLTAGE LOCKOUT
IN12 UVLO
IN34 UVLO
VIN12 rising
2.4
VIN12 hysteresis
0.1
VIN34 rising
1.5
VIN34 hysteresis
1.6
V
0.1
V
+160
°C
15
°C
THERMAL SHUTDOWN
Threshold
TA rising
Hysteresis
REFERENCE
Reference Bypass Output
Voltage
REF Supply Rejection
0.591
2.6V ≤ (VIN12 = VIN34) ≤ 5.5V
0.600
0.609
0.15
V
mV/V
LOGIC AND CONTROL INPUTS
EN_ Input Low Level
1.7V ≤ VIN34 ≤ 5.5V
2.6V ≤ VIN12 ≤ 5.5V
EN_ Input High Level
1.7V ≤ VIN34 ≤ 5.5V
2.6V ≤ VIN12 ≤ 5.5V
EN_ Input Leakage Current
VIN12 = VIN34 = 5.5V
0.4
1.44
TA = +25°C
TA = +85°C
V
V
-1
+1
0.001
µA
STEP-DOWN CONVERTERS
Minimum Adjustable Output
Voltage
2
MAX8668
0.6
_______________________________________________________________________________________
V
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
(VIN34 = VIN12 = 3.6V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Maximum Adjustable Output
Voltage
MAX8668
FB1, FB2 Regulation Voltage
MAX8668, no load,
VFB_ falling
TA = +25°C
0.588
0.600
0.612
TA = -40°C to +85°C
0.582
0.600
0.618
OUT1, OUT2 Regulation Voltage
MAX8667ETEJS+, no load, VOUT_
falling
TA = +25°C
1.274
1.300
1.326
TA = -40°C to +85°C
1.261
1.300
1.339
FB1, FB2 Line Regulation
MAX8668, VIN12 = 2.6V to 5.5V
0.01
%/V
%/V
OUT1, OUT2 Line Regulation
FB1, FB2 Bias Current
OUT1 Current Limit
OUT2 Current Limit
OUT1 On-Resistance
OUT2 On-Resistance
3.3
MAX8667, VIN12 = 2.8V to 5.5V
0.05
MAX8668, shutdown mode
0.1
MAX8668, VFB1 = 0.5V
0.01
700
900
1100
nMOSFET rectifier (valley current)
500
750
1000
pMOSFET switch (ILIMP2)
1333
1667
2000
nMOSFET rectifier (valley current)
1200
1500
1800
pMOSFET switch, ILX1 = -400mA
0.3
0.6
nMOSFET rectifier, ILX1 = 400mA
0.3
0.6
pMOSFET switch, ILX2 = -400mA
0.12
0.27
nMOSFET rectifier, ILX2 = 400mA
0.12
0.27
60
120
LX_ = 5.5V
TA = +25°C
-1
TA = +85°C
V
V
µA
pMOSFET switch (ILIMP1)
Rectifier-Off Current Threshold
(ILXOFF)
LX Leakage Current
V
+1
0.1
mA
mA
Ω
Ω
mA
µA
Minimum On-Time
100
ns
Minimum Off-Time
50
ns
LDO REGULATORS
Supply Current
Each LDO
Output-Voltage Accuracy
20
µA
1mA load, TA = +25°C
-1.5
+1.5
1mA to 300mA load
-3.0
+3.0
Line Regulation
VIN34 = 3.6V to 5.5V, 1mA load
Dropout Voltage
VIN34 = 1.8V, 300mA load
Current Limit
VOUT3, VOUT4 90% of nominal value
Soft-Start Ramp Time
To 90% of final value
0.1
ms
Output Noise
100Hz to 100kHz, 30mA load, VOUT3 and VOUT4 = 2.8V
75
µVRMS
Power-Supply Rejection Ratio
f < 1kHz, 30mA load
57
dB
1
kΩ
Shutdown Output Resistance
0.003
%
375
%/V
130
250
mV
420
465
mA
TIMING (See Figure 2)
Power-On Time (tPWRON)
Enable Time (tEN)
OUT1, OUT2
25
OUT3, OUT4
45
OUT1, OUT2
15
OUT3, OUT4
35
µs
µs
Note 1: All devices are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by design.
_______________________________________________________________________________________
3
MAX8667/MAX8668
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VIN12 = VIN34 = 3.6V, circuit of Figure 4, VOUT1 = 1.2V, VOUT2 = 1.8V, VOUT3 = 2.8V, VOUT4 = 2.8V, TA = +25°C, unless otherwise noted.)
OUT1 EFFICIENCY vs. LOAD CURRENT
(VOUT1 = 1.2V)
70
50
40
30
20
60
50
40
30
ONLY OUT2 ENABLED
1
100
10
1000
0.1
1
10
100
1000
0
10000
100
200
300
400
500
600
LOAD CURRENT (mA)
OUT2 LOAD REGULATION
OUT1 OUTPUT VOLTAGE
vs. INPUT VOLTAGE (600mA LOAD)
OUT2 OUTPUT VOLTAGE
vs. INPUT VOLTAGE (1200mA LOAD)
1.30
1.20
1.25
1.20
1.15
600
800
1000
1.65
1200
1.60
2.5
SWITCHING FREQUENCY
vs. LOAD CURRENT
3.0
3.5
2500
2000
OUT2
1500
1000
4.0
4.5
5.0
5.5
0
600
900
1200
LOAD CURRENT (mA)
1500
1800
3.5
4.0
4.5
5.0
5.5
NO-LOAD SUPPLY CURRENT vs. SUPPLY
VOLTAGE ALL REGULATOR ENABLED
NO-LOAD SUPPLY CURRENT
vs. SUPPLY VOLTAGE OUT1 AND OUT2 ONLY
120
MAX8667/88 toc08
100
80
SUPPLY VOLTAGE
RISING
60
40
SUPPLY VOLTAGE
FALLING
100
SUPPLY VOLTAGE
FALLING
80
60
SUPPLY VOLTAGE
RISING
40
20
0
300
3.0
INPUT VOLTAGE (V)
20
OUT1
2.5
INPUT VOLTAGE (V)
120
SUPPLY CURRENT (µA)
MAX8667/88 toc07
3000
1.75
1.05
LOAD CURRENT (mA)
3500
1.80
1.70
SUPPLY CURRENT (µA)
400
1.85
1.10
1.00
200
1.90
MAX8667/88 toc09
1.40
1.95
OUTPUT VOLTAGE (V)
1.50
1.30
MAX8667/88 toc06
1.35
OUTPUT VOLTAGE (V)
1.60
2.00
MAX8667/88 toc05
1.40
MAX8667/88 toc04
1.70
0
0.95
LOAD CURRENT (mA)
1.80
500
1.00
LOAD CURRENT (mA)
1.90
0
1.05
0.80
0
0.1
1.10
0.85
10
0
OUTPUT VOLTAGE (V)
1.15
0.90
ONLY OUT1 ENABLED
4
1.20
20
10
MAX8667/88 toc03
80
EFFICIENCY (%)
60
1.25
OUTPUT VOLTAGE (V)
70
OUT1 LOAD REGULATION
90
MAX8667/88 toc02
80
EFFICIENCY (%)
OUT2 EFFICIENCY vs. LOAD CURRENT
(VOUT2 = 1.8V)
MAX8667/88 toc01
90
SWITCHING FREQUENCY (kHz)
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
1.5
2.0
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5.0
5.5
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
VIN34 VOLTAGE
FALLING
40
2.85
2.80
2.75
2.70
2.65
2.60
1
2
3
4
5
60
50
40
30
20
0
2.50
2.5
3.0
SUPPLY VOLTAGE (V)
3.5
4.0
4.5
5.0
0
5.5
100
200
300
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
ENABLE WAVEFORMS
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX8667/88 toc14
1000
MAX8667/88 toc13
0
70
10
2.55
0
80
MAX8667/88 toc12
2.90
VIN34 VOLTAGE
RISING
20
IN12 = IN34
2.4Ω LOAD ON OUT1
3.6Ω LOAD ON OUT2
NO LOAD ON OUT3
NO LOAD ON OUT4
900
800
SUPPLY CURRENT (mA)
IIN34 (µA)
80
60
2.95
OUTPUT VOLTAGE (V)
100
3.00
MAX8667/88 toc11
VIN12 = 5.5V
MAX8667/88 toc10
120
OUT3 DROPOUT VOLTAGE
vs. LOAD CURRENT
OUT3 OUTPUT VOLTAGE
vs. INPUT VOLTAGE (300mA LOAD)
DROPOUT VOLTAGE (mV)
NO-LOAD SUPPLY CURRENT vs. SUPPLY
VOLTAGE OUT3 AND OUT4 ONLY
700
5V/div
EN1/EN2/
EN3/EN4
VOUT1
600
VOUT2
500
VOUT3
400
VOUT4
300
2V/div
2V/div
2V/div
2V/div
2A/div
IL1
200
2A/div
2A/div
IL2
100
IIN12 + IIN34
0
2.5
3.0
3.5
4.0
4.5
5.0
40µs/div
5.5
SUPPLY VOLTAGE (V)
OUT1 LOAD TRANSIENT
SHUTDOWN WAVEFORMS
MAX8667/88 toc16
MAX8667/88 toc15
EN1/EN2/
EN3/EN4
5V/div
VOUT1
VOUT2
100mV/div
(AC-COUPLED)
VOUT1
300mA
1V/div
VOUT3
1V/div
VOUT4
IOUT1
10mA
10mA
200mA/div
1V/div
IL1
200mA/div
1V/div
40µs/div
10µs/div
_______________________________________________________________________________________
5
MAX8667/MAX8668
Typical Operating Characteristics (continued)
(VIN12 = VIN34 = 3.6V, circuit of Figure 4, VOUT1 = 1.2V, VOUT2 = 1.8V, VOUT3 = 2.8V, VOUT4 = 2.8V, TA = +25°C, unless otherwise noted.)
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
Typical Operating Characteristics (continued)
(VIN12 = VIN34 = 3.6V, circuit of Figure 4, VOUT1 = 1.2V, VOUT2 = 1.8V, VOUT3 = 2.8V, VOUT4 = 2.8V, TA = +25°C, unless otherwise noted.)
OUT3 LOAD TRANSIENT
OUT2 LOAD TRANSIENT
MAX8667/88 toc18
MAX8667/88 toc17
200mV/div
(AC-COUPLED)
VOUT2
50mV/div
(AC-COUPLED)
VOUT3
600mA
IOUT2
10mA
10mA
500mA/div
300mA
IOUT3
200mA/div
500mA/div
IL2
0mA
0mA
10µs/div
10µs/div
OUT1 LIGHT-LOAD SWITCHING
WAVEFORMS
OUT4 LOAD TRANSIENT
MAX8667/88 toc20
MAX8667/88 toc19
50mV/div
(AC-COUPLED)
VOUT4
VOUT1
20mV/div
VLX1
2V/div
300mA
IOUT4
200mA/div
0mA
0mA
IL1
100mA/div
500µA LOAD
10µs/div
10µs/div
OUT2 LIGHT-LOAD SWITCHING
WAVEFORMS
OUT1 HEAVY-LOAD SWITCHING
WAVEFORMS
MAX8667/88 toc21
VOUT2
MAX8667/88 toc22
20mV/div
VLX2
2V/div
VOUT1
20mV/div
VLX1
2V/div
500mA/div
IL2
500mA/div
500µA LOAD
500µA LOAD
40µs/div
6
IL1
400ns/div
_______________________________________________________________________________________
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
OUT2 HEAVY-LOAD SWITCHING
WAVEFORMS
MAX8667/88 toc23
70
VOUT3 = 2.80V
ILOAD = 100Ω
COUT3 = 4.7µF
60
VOUT2
20mV/div
MAX8667/88 toc24
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
VLX2
2V/div
500mA/div
IL2
PSRR (dB)
50
40
30
20
10
500mA LOAD
0
400ns/div
0.01
0.1
1
10
100
1000
FREQUENCY (kHz)
OUT3 NOISE
OUT4 NOISE
MAX8667/88 toc25
MAX8667/88 toc26
100µV/div
100µV/div
VOUT3 = 2.80V
ILOAD = 100Ω
1ms/div
VOUT4 = 3.30V
ILOAD = 100Ω
1ms/div
_______________________________________________________________________________________
7
MAX8667/MAX8668
Typical Operating Characteristics (continued)
(VIN12 = VIN34 = 3.6V, circuit of Figure 4, VOUT1 = 1.2V, VOUT2 = 1.8V, VOUT3 = 2.8V, VOUT4 = 2.8V, TA = +25°C, unless otherwise noted.)
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
MAX8667/MAX8668
Pin Description
PIN
8
NAME
FUNCTION
MAX8667
MAX8668
1
EN3
EN3
2
OUT3
OUT3
Output of Regulator 3. Bypass OUT3 with a 4.7µF ceramic capacitor to GND. OUT3 is
discharged to GND through an internal 1kΩ in shutdown.
3
IN34
IN34
Input Voltage for LDO Regulators 3 and 4. Supply voltage range is from 1.7V to 5.5V. This
supply voltage must not exceed VIN12. Connect a 4.7µF or larger ceramic capacitor from IN34
to ground.
4
OUT4
OUT4
Output of Regulator 4. Bypass OUT4 with a 4.7µF ceramic capacitor to GND. OUT4 is
discharged to GND through an internal 1kΩ in shutdown.
5
EN4
EN4
Enable Input for Regulator 4. Drive EN4 high or connect to IN34 to turn on regulator 4. Drive low
to turn off regulator 4 and reduce input quiescent current.
6
GND
GND
Ground
7
REF
REF
Reference Output. Bypass REF with a 0.01µF ceramic capacitor to GND.
8
OUT2
—
—
FB2
Enable Input for Regulator 3. Drive EN3 high or connect to IN34 to turn on regulator 3. Drive low
to turn off regulator 3 and reduce input quiescent current.
Feedback Input for Regulator 2. Connect OUT2 directly to the output of step-down regulator 2.
Feedback Input for Regulator 2. Connect FB2 to the center of a resistor feedback divider
between the output of regulator 2 and ground to set the output voltage. See the Setting the
Output Voltages and Voltage Positioning section.
9
PGND2
PGND2
10
LX2
LX2
Inductor Connection for Regulator 2
Power Ground for Step-Down Regulator 2
11
IN12
IN12
Input Voltage for Step-Down Regulators 1 and 2. Supply voltage range is from 2.6V to 5.5V. This
supply voltage must not be less than VIN34. Connect a 10µF or larger ceramic capacitor from
IN12 to ground.
Inductor Connection for Regulator 1
12
LX1
LX1
13
PGND1
PGND1
14
OUT1
—
Feedback Input for Regulator 1. Connect OUT1 directly to the output of step-down regulator 1.
—
FB1
Feedback Input for Regulator 1. Connect FB1 to the center of a resistor feedback divider
between the output of regulator 1 and ground to set the output voltage. See the Setting the
Output Voltages and Voltage Positioning section.
15
EN1
EN1
Enable Input for Regulator 1. Drive EN1 high or connect to IN12 to turn on step-down regulator 1.
Drive low to turn off the regulator and reduce input quiescent current.
16
EN2
EN2
Enable Input for Regulator 2. Drive EN2 high or connect to IN12 to turn on step-down regulator 2.
Drive low to turn off the regulator and reduce input quiescent current.
—
EP
EP
Power Ground for Step-Down Regulator 1
Exposed Paddle. Connect to GND, PGND1, PGND2, and circuit ground.
_______________________________________________________________________________________
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
MAX8667/MAX8668
IN34
1.7V TO 5.5V
IN12
2.8V TO 5.5V
(2.6V TO 5.5V)
STEP-DOWN
IN
EN
OUT1
LX1
UVLO
GND
FB
EN
OUT1
(FB1)
PGND1
REF
REF AND BIAS
STEP-DOWN
IN
REF
EN
GND
LX2
OUT2
GND
FB
OUT2
(FB2)
PGND2
EN1
EN2
EN3
IN
PWRON LOGIC
AND ENABLES
EN
LDO
OUT
OUT3
OUT
OUT4
OUT3
GND
EN4
LDO
IN
EN
OUT4
GND
() ARE FOR THE MAX8668
Figure 1. Functional Diagram
_______________________________________________________________________________________
9
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
Detailed 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 outputs 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 (typ) with all regulators enabled. Dual,
low-quiescent-current, low-noise LDOs operate down to
1.7V supply voltage. The MAX8667/MAX8668 have
individual enable inputs for each output to facilitate any
supply sequencing.
Step-Down DC-DC Regulators
(OUT1, OUT2)
Step-Down Regulator Architecture
The MAX8667/MAX8668 step-down regulators are optimized for high-efficiency voltage conversion over a
wide load range, while maintaining excellent transient
response, minimizing external component size, and
minimizing output voltage ripple. The DC-DC converters (OUT1, OUT2) also feature an optimized on-resistance internal MOSFET switch and synchronous
rectifier to maximize efficiency. The MAX8667/
MAX8668 utilize a proprietary hysteretic-PWM control
scheme that switches with nearly fixed frequency at up
to 1.5MHz allowing for ultra-small external components.
The step-down converter output current is guaranteed
up to 600mA for OUT1 and 1200mA for OUT2.
When the step-down converter output voltage falls below
the regulation threshold, the error comparator begins a
switching cycle by turning the high-side p-channel
MOSFET switch on. This switch remains on until the minimum on-time (tON) expires and the output voltage is in
regulation or the current-limit threshold (I LIMP_ ) is
exceeded. Once off, the high-side switch remains off
until the minimum off-time (tOFF) expires and the output
voltage again falls below the regulation threshold.
During this off period, the low-side synchronous rectifier turns on and remains on until either the high-side
switch turns on or the inductor current reduces to the
rectifier-off current threshold (ILXOFF = 60mA typ). The
internal synchronous rectifier eliminates the need for an
external Schottky diode.
Input Supply and Undervoltage Lockout
The input voltage range of step-down regulators OUT1
and OUT2 is 2.6V to 5.5V. This supply voltage must be
greater than or equal to the LDO supply voltage (VIN34).
10
A UVLO circuit prevents step-down regulators OUT1
and OUT2 from switching when the supply voltage is
too low to guarantee proper operation. When VIN12 falls
below 2.4V (typ), OUT1 and OUT2 are shut down.
OUT1 and OUT2 turn on and begin soft-start when
VIN12 rises above 2.5V (typ).
Soft-Start
When initially powered up, or enabled with EN_, the
step-down regulators soft-start by gradually ramping
up the output voltage. This reduces inrush current during startup. See the startup waveforms in the Typical
Operating Characteristics section.
Current Limit
The MAX8667/MAX8668 limit the peak inductor current
of the p-channel MOSFET (ILIMP_). A valley current limit
is used to protect the step-down regulators during
severe overload and output short-circuit conditions.
When the peak current limit is reached, the internal
p-channel MOSFET turns off and remains off until the
output drops below regulation, the inductor current falls
below the valley current-limit threshold, and the minimum off-time has expired.
Voltage Positioning
The OUT1 and OUT2 output voltages and voltage positioning of the MAX8668 are set by a resistor network
connected to FB_. With this configuration, a portion of
the feedback signal is sensed on the switched side of
the inductor, and the output voltage droops slightly as
the load current is increased due to the DC resistance
of the inductor. This output voltage droop is known as
voltage positioning. Voltage positioning allows the load
regulation to be set to match the voltage droop during
a load transient, reducing the peak-to-peak output voltage deviation during a load transient, and reducing the
output capacitance requirements.
Dropout
As the input voltage approaches the output voltage, the
duty cycle of the p-channel MOSFET reaches 100%. In
this state, the p-channel MOSFET is turned on constantly (not switching), and the dropout voltage is the
voltage drop due to the output current across the onresistance of the internal p-channel MOSFET (RPCH)
and the inductor’s DC resistance (RL):
VDO = ILOAD (RPCH + RL )
LDO Linear Regulators (OUT3, OUT4)
The MAX8667/MAX8668 contain two low-dropout linear
regulators (LDOs), OUT3 and OUT4. The LDO output
voltages are factory preset, and each LDO supplies
______________________________________________________________________________________
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
Input Supply and Undervoltage Lockout
The input voltage range of LDO regulators OUT3 and
OUT4 is 1.7V to 5.5V. This supply voltage must be less
than or equal to the voltage applied to IN12 (VIN34 ≤
VIN12).
An undervoltage lockout circuit turns off the LDO regulators when the input supply voltage is too low to guarantee
proper operation. When VIN34 falls below 1.5V (typ),
OUT3 and OUT4 are shut down. OUT3 and OUT4 turn
on and begin soft-start when VIN34 rises above 1.6V (typ).
Soft-Start
When initially powered up, or enabled with EN_, the
LDOs soft-start by gradually ramping up the output
voltage. This reduces inrush current during startup. The
soft-start ramp time is typically 100µs from the start of
the soft-start ramp to the output reaching its nominal
regulation voltage.
Current Limit
The OUT3 and OUT4 output current is limited to 375mA
(min). If the output current exceeds the current limit, the
corresponding LDO output voltage drops.
Dropout
The maximum dropout voltage for the linear regulators
is 250mV at 300mA load. To avoid dropout, make sure
the IN34 supply voltage is at least 250mV higher than
the highest LDO output voltage.
Thermal-Overload Protection
Thermal-overload protection limits the total power dissipation in the MAX8667/MAX8668. Thermal-protection
circuits monitor the die temperature. If the die temperature exceeds +160°C, the IC is shut down, allowing the
IC to cool. Once the IC has cooled by 15°C, the IC is
enabled again. This results in a pulsed output during
continuous thermal-overload conditions. The thermaloverload protection protects the MAX8667/MAX8668 in
the event of fault conditions. For continuous operation,
do not exceed the absolute maximum junction temperature of +150°C. See the Thermal Considerations section for more information.
tPWRON IS THE PERIOD REQUIRED TO ENABLE FROM SHUTDOWN
IN12
tPWRON
ENx
OUTx
tEN IS THE ENABLE TIME FOR SUBSEQUENT ENABLE
SIGNALS FOLLOWING THE FIRST ENABLE
ENy
tEN
OUTy
ENx, ENy ARE ANY COMBINATION OF EN1–EN4.
Figure 2. Timing Diagram
______________________________________________________________________________________
11
MAX8667/MAX8668
loads up to 300mA. The LDOs include an internal reference, error amplifier, p-channel pass transistor, and
internal voltage-dividers. Each error amplifier compares
the reference voltage to the output voltage (divided by
the internal voltage-divider) and amplifies the difference. If the divided feedback voltage is lower than the
reference voltage, the pass-transistor gate is pulled
lower, allowing more current to pass to the outputs and
increasing the output voltage. If the divided feedback
voltage is too high, the pass-transistor gate is pulled
up, allowing less current to pass to the output.
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
C3
4.7µF
INPUT
2.8V TO 5.5V
1.7V TO 5.5V
C2
10µF
IN12
IN34
EN1
EN3
EN2
REF
OUT3
EN4
C1
0.01µF
300mA
300mA
OUT4
C8
4.7µF
GND
C9
4.7µF
MAX8667
L2
2.2µH
OUT2
1.2A
L1
2.2µH
OUT2
PGND2
C7
2.2µF
OUT1
600mA
LX1
LX2
OUT1
C6
2.2µF
PGND1
Figure 3. MAX8667 Typical Application Circuit
INPUT
2.6V TO 5.5V
C2
10µF
IN12
EN1
IN34
EN3
EN4
EN2
REF
OUT4, 300mA
OUT4
C1
0.01µF
C8
4.7µF
GND
MAX8668
L2
2.2µH
OUT2
0.6V TO 3.3V, 1.2A
OUT3, 300mA
OUT3
LX2
L1
2.2µH
R3
R1
R6*
FB2
C6
2.2µF
FB1
C5
C10*
OUT1
0.6V TO 3.3V, 600mA
LX1
R5*
C7
2.2µF for VOUT2 ≤ 1.8V
4.7µF for VOUT2 > 1.8V
C9
4.7µF
C4
R4
PGND1
PGND2
R2
*C10, R5, AND R6 ARE OPTIONAL
Figure 4. MAX8668 Typical Application Circuit
12
______________________________________________________________________________________
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
Setting the Output Voltages
and Voltage Positioning
L1
The LDO output voltages of the MAX8667/MAX8668,
and the step-down outputs of the MAX8667 are factory
preset. See the Selector Guide to find the part number
corresponding to the desired output voltages.
The OUT1 and OUT2 output voltages of the MAX8668
are set by a resistor network connected to FB_ as
shown in Figure 5. With this configuration, a portion of
the feedback signal is sensed on the switched side of
the inductor (LX), and the output voltage droops slightly
as the load current is increased due to the DC resistance of the inductor (DCR). This allows the load regulation to be set to match the voltage droop during a
load transient (voltage positioning), reducing the peakto-peak output-voltage deviation during a load transient, and reducing the output capacitance
requirements.
For the simplest method of setting the output voltage,
R6 is not installed. Choose the value of R2 (a good
starting value is 100kΩ), and then calculate the value of
R1 as follows:
⎛V
⎞
R1 = R2 × ⎜ OUT − 1⎟
⎝ VFB
⎠
where VFB is the feedback regulation voltage (0.6V).
With the voltage set in this manner, the voltage positioning depends only on the DCR, and the maximum
output voltage droop is:
∆VOUT(MAX) = DCR × IOUT(MAX)
Setting the Output Voltages with
Reduced Voltage Positioning
To obtain less voltage positioning than described in the
previous section, use the following procedure for setting the output voltages. The OUT1 and OUT2 output
voltages and voltage positioning of the MAX8668 are
set by a resistor network connected to FB_ as shown in
Figure 5.
To set the output voltage (VOUT), first select a value for
R2 (a good starting value is 100kΩ). Then calculate the
value of REQ (the equivalent parallel resistance of R1
and R6) as follows:
⎛V
⎞
REQ = ⎜ OUT − 1⎟ × R2
⎝ VFB
⎠
where VFB is the feedback-regulation voltage (0.6V).
DCR
LX_
OUT
ESR
R1
R6
(OPTIONAL)
C4
RLOAD
C6
FB_
R2
Figure 5. MAX8668 Feedback Network
Calculate the factor m based on the desired load-regulation improvement:
m=
IOUT(MAX) × DCR
∆VOUT(DESIRED)
where IOUT(MAX) is the maximum output current, DCR is
the inductor series resistance, and ∆VOUT(DESIRED) is the
maximum allowable droop in the output voltage at full
load. The calculated value for m must be between 1.1 and
2; m = 2 results in a 2x improvement in load regulation.
Now calculate the values of R1 and R6 as follows:
R1 = REQ × m
R6 = REQ × m
m−1
The value of R1 should always be lower than the value
of R6.
Power-Supply Sequencing
The MAX8667/MAX8668 have individual enable inputs
for each regulator to allow complete control over the
power sequencing. When all EN_ inputs are low, the IC
is in low-power shutdown mode, reducing the supply
current to less than 1µA. After one of the EN_ inputs
asserts high, the corresponding regulator begins softstart after a delay of tEN (see Figure 2). The first output
enabled from shutdown mode or initially powering up
the IC has a longer delay (tPWRON) as the IC exits the
low-power shutdown mode.
Inductor Selection
The MAX8667/MAX8668 step-down converters operate
with inductors between 2.2µH and 4.7µH. Low inductance values are physically smaller, but require faster
switching, resulting in some efficiency loss. The inductor’s DC current rating must be high enough to account
______________________________________________________________________________________
13
MAX8667/MAX8668
Applications Information
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
Table 1. Recommended Inductors
MANUFACTURER
INDUCTOR
L (µH)
RL (mΩ)
FDK
MIPF2016
2.2
110
1.1
2.0 x 1.6 x 1.0
FDK
MIPF2520D
2.2
80
1.3
2.5 x 2.0 x 1.0
LQH32CN2R2M5
2.2
97
0.79
3.2 x 2.5 x 1.55
3.2 x 1.6 x 0.95
Murata
CURRENT RATING (A)
L x W x H (mm)
LQM31P
2.2
220
0.9
Sumida
CDRH2D09
2.2
120
0.44
3.2 x 3.2 x 1.0
TDK
GLF251812T
2.2
200
0.6
2.5 x 1.8 x 1.35
TOKO
D2812C
2.2
140
0.77
2.8 x 2.8 x 1.2
TOKO
MDT2520-CR
2.2
80
0.7
2.5 x 2.0 x 1.0
TPC Series
2.2
55
1.8
4.0 x 4.0 x 1.1
TPC Series
4.7
124
1.35
4.0 x 4.0 x 1.1
CB2518T
2.2
90
0.51
2.5 x 1.8 x 2.0
Wurth
Taiyo Yuden
for peak ripple current and load transients. The stepdown converter’s unique architecture has minimal current overshoot during startup and load transients and in
most cases, an inductor capable of 1.3x the maximum
load current is acceptable.
For output voltages above 2V, when light-load efficiency
is important, the minimum recommended inductor is
2.2µH. For optimum voltage-positioning load transients,
choose an inductor with DC series resistance in the
50mΩ to 150mΩ range. For higher efficiency at heavy
loads (above 200mA) and minimal load regulation,
keep the inductor resistance as small as possible. For
light-load applications (up to 200mA), higher resistance
is acceptable with very little impact on performance.
small and to ensure regulation loop stability. These
capacitors must have low impedance at the switching
frequency. Surface-mount ceramic capacitors are a
good choice due to their small size and low ESR. Make
sure the capacitor maintains its capacitance over temperature and DC bias. Ceramic capacitors with X5R or
X7R temperature characteristics generally perform well.
The output capacitance can be very low. For most applications, a 2.2µF ceramic capacitor is sufficient. For C7 of
the MAX8668, a 2.2µF (VOUT2 ≤ 1.8V) or a 4.7µF (VOUT2
> 1.8V) ceramic capacitor is recommended. For optimum load-transient performance and very low output ripple, the output capacitor value in µF should be equal to
or greater than the inductor value in µH.
Capacitor Selection
Feed-Forward Capacitor
The feed-forward capacitors on the MAX8668 (C4 and
C5 in Figure 4) set the feedback loop response, control
the switching frequency, and are critical in obtaining
the best efficiency possible. Small X7R and C0G
ceramic capacitors are recommended.
For OUT1, calculate the value of C4 as follows:
C4 = 1.2 x 10-5(s/V) x (VOUT / R1)
For OUT2, calculate the value of C5 and C10 as follows:
Cff = 1.2 x 10-5(s/V) x (VOUT / R3)
Cff = C5 + (C10 / 2)
(C10 / C5) + 1 = (VOUT / VFB), where VFB is 0.6V.
Rearranging the formulas:
C10 = 2 x Cff x (VOUT - VFB)/(VOUT + VFB)
C5 = Cff – (C10 / 2)
Input Capacitors
The input capacitor for the step-down converters (C2 in
Figures 3 and 4) reduces the current peaks drawn from
the battery or input power source and reduces switching noise in the IC. The impedance of C2 at the switching frequency should be very low. Surface-mount
ceramic capacitors are a good choice due to their
small size and low ESR. Make sure the capacitor maintains its capacitance over temperature and DC bias.
Ceramic capacitors with X5R or X7R temperature characteristics generally perform well. A 10µF ceramic
capacitor is recommended.
A 4.7µF ceramic capacitor is recommended for the
LDO input capacitor (C3 in Figure 3).
Step-Down Output Capacitors
The step-down output capacitors (C6 and C7 in Figures
3 and 4) are required to keep the output-voltage ripple
14
______________________________________________________________________________________
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
LDO Output Capacitor and Stability
Connect a 4.7µF ceramic capacitor between OUT3 and
GND, and a second 4.7µF ceramic capacitor from
OUT4 to GND. For a constant loading above 10mA, the
output capacitors can be reduced to 2.2µF. The equivalent series resistance (ESR) of the LDO output capacitors affects stability and output noise. Use output
capacitors with an ESR of 0.1Ω or less to ensure stable
operation and optimum transient response. Surfacemount ceramic capacitors have very low ESR and are
commonly available. Connect these capacitors as
close as possible to the IC’s pins to minimize PCB trace
inductance.
Thermal Considerations
The maximum package power dissipation of the
MAX8667/MAX8668 is 1667mW. Make sure the power
dissipated by the MAX8667/MAX8668 does not exceed
this rating. The total IC power dissipation is the sum of
the power dissipation of the four regulators:
PD = PD1 + PD2 + PD3 + PD4
Estimate the OUT1 and OUT2 power dissipations as
follows:
PD1 = IOUT1 × VOUT1 ×
1− η
η
PD2 = IOUT2 × VOUT2 ×
1− η
η
where RL is the inductor’s DC resistance, and η is the
efficiency (see the Typical Operating Characteristics
section).
Calculate the OUT3 and OUT4 power dissipations as
follows:
PD3 = IOUT3 × (VIN34 − VOUT3 )
PD4 = IOUT4 × (VIN34 − VOUT4 )
The maximum junction temperature of the MAX8667/
MAX8668 is +150°C. The junction-to-case thermal
resistance (θJC) of the MAX8667/MAX8668 is 6.9°C/W.
When mounted on a single-layer PCB, the junction to
ambient thermal resistance (θ JA ) is about 64°C/W.
Mounted on a multilayer PCB, θJA is about 48°C/W.
Calculate the junction temperature of the
MAX8667/MAX8668 as follows:
TJ = TA + PD × θJA
where TA is the maximum ambient temperature. Make
sure the calculated value of TJ does not exceed the
+150°C maximum.
PCB Layout
High switching frequencies and relatively large peak
currents make PCB layout a very important aspect of
design. Good design minimizes excessive EMI on the
feedback paths and voltage gradients in the ground
plane, both of which can result in instability or regulation errors. Connect the input capacitors as close as
possible to the IN_ and PGND_ pins. Connect the
inductor and output capacitors as close as possible to
the IC and keep the traces short, direct, and wide.
The feedback network traces are sensitive to inductor
magnetic field interference. Route these traces away
from the inductors and noisy traces such as LX. Keep
the feedback components close to the FB_ pin.
Connect GND and PGND_ to the ground plane.
Connect the exposed paddle to the ground plane with
one or more vias to help conduct heat away from the
IC.
Refer to the MAX8668 evaluation kit for a PCB layout
example.
______________________________________________________________________________________
15
MAX8667/MAX8668
C10 is needed if VOUT > 1.5V or VIN12 can be less than
VOUT / 0.65.
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
Ordering Information (continued)
PART
PKG CODE
TOP MARK
MAX8667ETEHR+
T1633-4
AFJ
MAX8667ETEJS+
T1633-4
MAX8668ETEA+
T1633-4
MAX8668ETEP+
Selector Guide
PART
OUT1
(V)
OUT2
(V)
OUT3
(V)
OUT4
(V)
AFQ
MAX8667ETEAA+
1.20
1.80
2.80
2.80
AER
MAX8667ETEAB+
1.20
1.80
2.85
2.85
T1633-4
AFK
MAX8667ETEAC+
1.20
1.80
1.20
1.20
MAX8668ETEQ+
T1633-4
AFR
MAX8667ETECQ+
1.60
1.80
2.80
1.20
MAX8668ETET+
T1633-4
AFS
MAX8667ETEHR+
1.80
1.20
2.60
2.80
MAX8668ETEU+
T1633-4
AFL
MAX8667ETEJS+
1.30
1.30
3.30
2.70
MAX8668ETEV+
T1633-4
AFT
MAX8668ETEA+
ADJ
ADJ
2.80
2.80
MAX8668ETEW+
T1633-4
AFU
MAX8668ETEP+
ADJ
ADJ
3.30
1.80
MAX8668ETEX+
T1633-4
AFV
MAX8668ETEQ+
ADJ
ADJ
2.80
1.20
MAX8668ETET+
ADJ
ADJ
3.30
3.30
MAX8668ETEU+
ADJ
ADJ
3.30
2.80
MAX8668ETEV+
ADJ
ADJ
3.30
2.50
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.
MAX8668ETEW+
ADJ
ADJ
3.30
3.00
MAX8668ETEX+
ADJ
ADJ
2.80
1.80
Chip Information
PROCESS: BiCMOS
16
______________________________________________________________________________________
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
12x16L QFN THIN.EPS
(NE - 1) X e
E
MARKING
E/2
D2/2
(ND - 1) X e
D/2
AAAA
e
CL
D
D2
k
CL
b
0.10 M C A B
E2/2
L
E2
0.10 C
C
L
0.08 C
C
L
A
A2
A1
L
L
e
e
PACKAGE OUTLINE
8, 12, 16L THIN QFN, 3x3x0.8mm
21-0136
I
1
2
______________________________________________________________________________________
17
MAX8667/MAX8668
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
MAX8667/MAX8668
1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
PKG
8L 3x3
12L 3x3
REF.
MIN. NOM. MAX.
MIN. NOM. MAX.
MIN. NOM. MAX.
A
0.70
0.75
0.80
0.70
0.75
0.80
0.70
0.75
0.80
b
0.25
0.30
0.35
0.20
0.25
0.30
0.20
0.25
0.30
D
2.90
3.00
3.10
2.90
3.00
3.10
2.90
3.00
3.10
E
2.90
3.00
3.10
2.90
3.00
3.10
2.90
3.00
3.10
e
L
0.65 BSC.
0.35
0.55
16L 3x3
0.50 BSC.
0.50 BSC.
0.75
0.45
0.55
0.65
0.30
0.40
N
8
12
16
ND
2
3
4
NE
2
3
4
0
A1
A2
k
0.02
0.05
0
0.25
-
0.02
0.05
0
0.20 REF
0.20 REF
-
0.25
-
EXPOSED PAD VARIATIONS
0.02
0.50
0.05
0.20 REF
-
0.25
-
PKG.
CODES
TQ833-1
E2
D2
PIN ID
MIN.
NOM.
MAX.
MIN.
NOM.
MAX.
0.25
0.70
1.25
0.25
0.70
1.25
0.35 x 45°
JEDEC
WEEC
T1233-1
0.95
1.10
1.25
0.95
1.10
1.25
0.35 x 45°
WEED-1
T1233-3
0.95
1.10
1.25
0.95
1.10
1.25
0.35 x 45°
WEED-1
T1233-4
0.95
1.10
1.25
0.95
1.10
1.25
0.35 x 45°
WEED-1
T1633-2
0.95
1.10
1.25
0.95
1.10
1.25
0.35 x 45°
WEED-2
T1633F-3
0.65
0.80
0.95
0.65
0.80
0.95
0.225 x 45°
WEED-2
T1633FH-3
0.65
0.80
0.95
0.65
0.80
0.95
0.225 x 45°
WEED-2
T1633-4
0.95
1.10
1.25
0.95
1.10
1.25
0.35 x 45°
WEED-2
T1633-5
0.95
1.10
1.25
0.95
1.10
1.25
0.35 x 45°
WEED-2
-
NOTES:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994.
ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES.
N IS THE TOTAL NUMBER OF TERMINALS.
THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO
JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED
WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR
MARKED FEATURE.
DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.20 mm AND 0.25 mm
FROM TERMINAL TIP.
ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY.
DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION.
COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.
DRAWING CONFORMS TO JEDEC MO220 REVISION C.
MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY.
NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY.
WARPAGE NOT TO EXCEED 0.10mm.
PACKAGE OUTLINE
8, 12, 16L THIN QFN, 3x3x0.8mm
21-0136
I
2
2
Revision History
Pages changed at Rev 1: 1, 12, 14, 18
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implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
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