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PDF MAX1536 Data sheet ( Hoja de datos )
| Número de pieza | MAX1536 | |
| Descripción | 3.6A 1.4MHz Low-Voltage Internal-Switch Step-Down Regulator with Dynamic Output Voltage Control | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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LCJ/JH 9/22/05 (P1)
19-2729; Rev 1; 8/05
EVAALVUAAILTAIOBNLEKIT
www.DataSheet4U.com
3.6A, 1.4MHz, Low-Voltage, Internal-Switch Step-
Down Regulator with Dynamic Output Voltage Control
General Description
The MAX1536 constant-off-time, pulse-width-modulated
(PWM) step-down DC-to-DC converter is ideal for use in
+5.0V and +3.3V to low voltages for notebook and sub-
notebook computers. The MAX1536 features an internal
PMOS power switch and internal synchronous rectifica-
tion for high efficiency and reduced component count. No
external Schottky diode is required across the internal
synchronous rectifier switch. The internal 54mΩ PMOS
power switch and 47mΩ NMOS synchronous-rectifier
switch easily deliver continuous load currents up to 3.6A.
The MAX1536 produces dynamically adjustable output
voltages for chipsets and graphics processor cores using
a logic-level control signal. The MAX1536 achieves effi-
ciencies as high as 96%.
The MAX1536 uses a unique current-mode, constant-off-
time, PWM control scheme. It has selectable Idle
ModeTM to maintain high efficiency during light-load
operation, or fixed-PWM mode for low output ripple. The
programmable constant-off-time architecture allows a
wide range of switching frequencies up to 1.4MHz, opti-
mizing performance trade-offs between efficiency, output
switching noise, component size, and cost. The
MAX1536 features a digital soft-start to limit surge cur-
rents during startup, a 100% duty-cycle mode for low-
dropout operation, and a low-power shutdown mode that
disconnects the input from the output and reduces supply
current below 1µA. The MAX1536 is available in a 28-pin
thin QFN package with an exposed backside pad.
________________________Applications
Chipset/Graphics Cores
with Dual-Supply Voltages
Active Termination Buses
Notebook Computers
DDR Memory Termination
Pin Configuration
Features
♦ Dynamically Selectable Output Voltage from
+0.7V to VIN
♦ Internal PMOS/NMOS Switches
54mΩ/47mΩ On-Resistance at VIN = +4.5V
63mΩ/53mΩ On-Resistance at VIN = +3.0V
♦ +3.0V to +5.5V Input Voltage Range
♦ 1.4MHz Maximum Switching Frequency
♦ 2V ±0.75% Reference Output
♦ Constant-Off-Time PWM Operation
♦ Selectable Idle Mode/PWM Operation at Light
Loads
♦ 100% Duty Factor in Dropout
♦ Digital Soft-Start Inrush Current Limiting
♦ <1µA Typical Shutdown Supply Current
♦ <750µA Quiescent Supply Current
♦ Thermal Shutdown
♦ 1% VOUT Accuracy Over Line and Load
♦ External Reference Input
♦ Power-Good Window Comparator
♦ Selectable Power-Good Blanking Time During
Output-Voltage Transition
Ordering Information
PART
MAX1536ETI
MAX1536ETI+
TEMP RANGE
-40oC to +85oC
-40oC to +85oC
PIN-PACKAGE
28 Thin QFN 5mm x 5mm
28 Thin QFN 5mm x 5mm
+Denotes lead-free package.
Minimal Operating Circuit
TOP VIEW
21 20 19 18 17 16 15
PGND 22
14 REF
PGND 23
13 REFIN
LX 24
12 OD
N.C. 25
LX 26
MAX1536
11 OD
10 GATE
PGND 27
PGND 28
EXPOSED PADDLE
9 TOFF
8 N.C.
123456 7
VIN
+3.0V TO +5.5V
IN LX
VCC
SHDN
FB
PGND
AGND
COMP MAX1536
PGOOD
REF
TOFF REFIN
VOUT
+0.7V TO VIN
THIN QFN
A "+" SIGN WILL REPLACE THE FIRST PIN INDICATOR ON LEAD-FREE PACKAGES.
Idle Mode is a trademark of Maxim Integrated Products, Inc.
SKIP
________________________________________________________________ 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  
www.DataSheet4U.com
3.6A, 1.4MHz, Low-Voltage, Internal-Switch Step-
Down Regulator with Dynamic Output Voltage Control
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, VIN = VCC = VSHDN = +3.3V, VREFIN = +1.5V, SKIP = AGND, TA = -40°C to +85°C, unless otherwise noted.) (Note 5)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX UNITS
INPUTS AND OUTPUTS
Logic Input Threshold
V SHDN,
V SKIP,
V GATE
SHDN, SKIP, GATE, VIN = VCC = +3.3V,
rising edge, hysteresis = 100mV
SHDN, SKIP, GATE, VIN = VCC = +5.0V,
rising edge, hysteresis = 100mV
0.9
1.15
1.6
V
1.95
FBLANK Logic Thresholds
VFBLANK
FBLANK = VCC
FBLANK = REF
FBLANK = open
VCC - 0.2
1.8
0.8
2.2
V
1.2
FBLANK = AGND
0.2
OD On-Resistance
ROD GATE = VCC
25 Ω
OD On-Resistance
ROD GATE = AGND
25 Ω
Note 2: Guaranteed by design and not production tested.
Note 3: To limit input surge currents, the current-limit threshold is set to 25% of its final value (25% x 4.8A = 1.2A) when the
MAX1536 is enabled or powered up. The current-limit threshold is increased by 25% every 256 LX cycles. The current-limit
threshold is at its final level of 4.8A after 768 LX cycles. See the Internal Soft-Start Circuit section.
Note 4: The upper and lower PGOOD thresholds are expressed as a ratio of VFB with respect to VREFIN.
VFB-VREFIN x100%
VREFIN
Note 5: Specifications to -40°C are guaranteed by design and are not production tested.
Typical Operating Characteristics
(MAX1536 Circuit of Figure 1, TA = +25°C, unless otherwise noted.)
EFFICIENCY vs. OUTPUT CURRENT
(VIN = 5V, L = 1.5μH)
100 PWM MODE
90 IDLE MODE
80
70
60
VOUT = 2.5V
RTOFF = 54.9kΩ
50
40
VOUT = 1.8V
RTOFF = 93.1kΩ
30
20 VOUT = 0.7V
10 RTOFF = 200kΩ
0
0.001
0.01 0.1
1
OUTPUT CURRENT (A)
10
OUTPUT VOLTAGE vs. OUTPUT CURRENT
(VIN = 5V, L = 1.5μH)
1.806
RTOFF = 93.1kΩ
1.804
1.802
1.800
1.798
IDLE MODE
PWM MODE
1.796
1.794
0.001
0.01 0.1
1
OUTPUT CURRENT (A)
10
EFFICIENCY vs. OUTPUT CURRENT
(VIN = 3.3V, L = 1.2μH)
100
90
80
70
60
50
40
30
20
10
0
0.001
VOUT = 2.5V
RTOFF = 42.2kΩ
VOUT = 1.8V
RTOFF = 75kΩ
VOUT = 0.7V
RTOFF = 165kΩ
PWM MODE
IDLE MODE
0.01 0.1
1
OUTPUT CURRENT (A)
10
_______________________________________________________________________________________ 5
5 Page 
www.DataSheet4U.com
3.6A, 1.4MHz, Low-Voltage, Internal-Switch Step-
Down Regulator with Dynamic Output Voltage Control
Table 2. Component Manufacturers
SUPPLIER
Coilcraft
Coiltronics
Kemet
Sanyo
Sumida
COMPONENT
Inductors
Inductors
Capacitors
Capacitors
Inductors
Taiyo Yuden
Capacitors
TDK
TOKO
Capacitors
Inductors
PHONE
800-322-2645 (USA)
561-752-5000 (USA)
408-986-0424 (USA)
818-998-7322 (USA)
408-982-9660 (USA)
03-3667-3408 (Japan),
408-573-4150 (USA)
847-803-6100 (USA),
81-3-5201-7241 (Japan)
858-675-8013 (USA)
WEBSITE
www.coilcraft.com
www.coiltronics.com
www.kemet.com
www.sanyo.com
www.sumida.com
www.t-yuden.com
www.component.tdk.com
www.toko.com
PGOOD
REF
PGOOD
COMPARATOR
REFIN
OD
COMP
VCC
MAX1536
SHDN
Gm
SUMMING
COMPARATOR
CURRENT
SENSE
PWM LOGIC
FB AND
OD DRIVERS
FBLANK
DECODE AND
TIMER
TIMER
CURRENT
2.0V SENSE
REF
GATE
FBLANK
REF
AGND
TOFF SKIP
VCC
*FB
IN
VIN
CIN
VIN
+3.0V TO +5.5V
L
LX
PGND
VOUT
+0.7V TO VIN
COUT
*FOR VOUT > 2.0V, USE AN FB RESISTIVE DIVIDER
*FROM VOUT TO AGND.
Figure 2. MAX1536 Functional Diagram
extended off-time to control the current. Operation dur-
ing a short-circuit or overload is similar to forced-PWM
mode except the off-time is 4 × tOFF. At the end of each
off-time, the PMOS switch turns on and remains on until
the output is in regulation or the current through the
switch increases to the 4.8A current limit. When the
PMOS switch turns off, it remains off for four times the
programmed off-time (tOFF), and the NMOS synchro-
nous switch turns on. Since either the NMOS or the
PMOS switch is always on, the inductor current is con-
tinuous. The RMS inductor current during a short circuit
remains below the 4.8A current-limit threshold. The
MAX1536 operates using the extended off-time until the
short-circuit or overload is removed and VFB > 0.3 ×
VREFIN. Prolonged short circuit or overload can result in
thermal shutdown.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet MAX1536.PDF ] | |
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