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PDF MAX8667 Data sheet ( Hoja de datos )
| Número de pieza | MAX8667 | |
| Descripción | (MAX8667 / MAX8668) First Dual Step-Down DC-DC Converters | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MAX8667 (archivo pdf) en la parte inferior de esta página. Total 18 Páginas | ||
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19-0784; Rev 0; 4/07
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.
Applications
Cell Phones/Smartphones
PDA and Palmtop Computers
Portable MP3 and DVD Players
Digital Cameras, Camcorders
PCMCIA Cards
Handheld Instruments
Typical Operating Circuit
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
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.
+Denotes a lead-free package.
Ordering Information continued at the end of data sheet.
Selector Guide appears at the end of data sheet.
Pin Configuration
2.6V TO 5.5V
10μF
0.01μF
600mA
2.2μH
2.2μF
IN12
EN1
EN2
REF
IN34
EN3
EN4
OUT3
OUT4
GND
4.7μF
4.7μF
300mA
300mA
4.7μF
MAX8667
LX1
OUT1
PGND1
LX2
OUT2
PGND2
2.2μH
2.2μF
1.2A
TOP VIEW
12 11 10 9
PGND1 13
8 OUT2 (FB2)
OUT1 (FB1) 14
EN1 15
EN2 16
MAX8667
MAX8668
7 REF
6 GND
5 EN4
1234
THIN QFN
(3mm x 3mm)
( ) ARE FOR THE MAX8668
________________________________________________________________ Maxim Integrated Products 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 page  
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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.)
NO-LOAD SUPPLY CURRENT vs. SUPPLY
VOLTAGE OUT3 AND OUT4 ONLY
120
VIN12 = 5.5V
100
80
60 VIN34 VOLTAGE
FALLING
40
20
0
0
VIN34 VOLTAGE
RISING
1234
SUPPLY VOLTAGE (V)
5
OUT3 OUTPUT VOLTAGE
vs. INPUT VOLTAGE (300mA LOAD)
3.00
2.95
2.90
2.85
2.80
2.75
2.70
2.65
2.60
2.55
2.50
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
80
70
60
50
40
30
20
10
0
0
OUT3 DROPOUT VOLTAGE
vs. LOAD CURRENT
100 200
LOAD CURRENT (mA)
300
SUPPLY CURRENT vs. SUPPLY VOLTAGE
1000
900 IN12 = IN34
2.4Ω LOAD ON OUT1
800 3.6Ω LOAD ON OUT2
700
NO LOAD ON OUT3
NO LOAD ON OUT4
600
500
400
300
200
100
0
2.5 3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY VOLTAGE (V)
EN1/EN2/
EN3/EN4
VOUT1
VOUT2
VOUT3
VOUT4
IL1
IL2
IIN12 + IIN34
ENABLE WAVEFORMS
MAX8667/88 toc14
5V/div
2V/div
2V/div
2V/div
2V/div
40μs/div
2A/div
2A/div
2A/div
EN1/EN2/
EN3/EN4
VOUT1
VOUT2
VOUT3
VOUT4
SHUTDOWN WAVEFORMS
MAX8667/88 toc15
5V/div
1V/div
1V/div
OUT1 LOAD TRANSIENT
MAX8667/88 toc16
VOUT1
IOUT1
10mA
300mA
10mA
100mV/div
(AC-COUPLED)
200mA/div
40μs/div
1V/div
1V/div
IL1 200mA/div
10μs/div
_______________________________________________________________________________________ 5
5 Page 
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1.5MHz Dual Step-Down DC-DC Converters
with Dual LDOs and Individual Enables
loads up to 300mA. The LDOs include an internal refer-
ence, 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 differ-
ence. 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.
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 regula-
tors 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 dissi-
pation in the MAX8667/MAX8668. Thermal-protection
circuits monitor the die temperature. If the die tempera-
ture 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 thermal-
overload protection protects the MAX8667/MAX8668 in
the event of fault conditions. For continuous operation,
do not exceed the absolute maximum junction temper-
ature of +150°C. See the Thermal Considerations sec-
tion for more information.
IN12
ENx
tPWRON
tPWRON IS THE PERIOD REQUIRED TO ENABLE FROM SHUTDOWN
OUTx
ENy
OUTy
tEN IS THE ENABLE TIME FOR SUBSEQUENT ENABLE
SIGNALS FOLLOWING THE FIRST ENABLE
tEN
ENx, ENy ARE ANY COMBINATION OF EN1–EN4.
Figure 2. Timing Diagram
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet MAX8667.PDF ] | |
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