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PDF MAX17552 Data sheet ( Hoja de datos )
| Número de pieza | MAX17552 | |
| Descripción | Synchronous Step-Down DC-DC Converter | |
| Fabricantes | Maxim Integrated | |
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MAX17552
EVALUATION KIT AVAILABLE
60V, 100mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converter
with 22µA No-Load Supply Current
General Description
The MAX17552 high-efficiency, high-voltage, syn-
chronous step-down DC-DC converter with integrated
MOSFETs operates over a 4V to 60V input voltage range.
The converter can deliver output current up to 100mA at
output voltages of 0.8V to 0.9 x VIN. The output voltage
is accurate to within ±1.75% over the -40°C to +125°C
temperature range.
The device employs a peak-current-mode control
architecture with a MODE pin that can be used to operate
the device in pulse-width modulation (PWM) or pulse-
frequency modulation (PFM) control schemes. PWM
operation provides constant frequency operation at all
loads and is useful in applications sensitive to variable
switching frequency. PFM operation disables negative
inductor current and additionally skips pulses at light
loads for high efficiency. The converter consumes only
22µA of no-load supply current in PFM mode. The low-
resistance, on-chip MOSFETs ensure high efficiency at
full load and simplify PCB layout.
The device offers programmable switching frequency
to optimize solution size and efficiency. Programmable
soft-start allows the user to reduce the inrush currents.
An EN/UVLO pin allows the user to turn on/off the device
at the desired input-voltage level. An open-drain RESET
pin allows output-voltage monitoring. The device operates
over the -40°C to +125°C industrial temperature range
and is available in a compact 10-pin (3mm x 2mm) TDFN
and 10-pin (3mm x 3mm) μMAX® packages. Simulation
models are available.
Applications
● Industrial Sensors and Process Control
● 4mA–20mA Current-Loop Powered Sensors
● High-Voltage LDO Replacement
● Battery-Powered Equipment
● HVAC and Building Control
● General-Purpose Point-of-Load
Benefits and Features
● Eliminates External Components and Reduces Total
Cost
• No Schottky—Synchronous Operation for High
Efficiency and Reduced Cost
• Internal Compensation
• Fixed Internal 5.1ms or Programmable Soft-Start
• All-Ceramic Capacitors, Ultra-Compact Layout
● Reduces Number of DC-DC Regulators to Stock
• Wide 4V to 60V Input Voltage Range
• Adjustable 0.8V to 0.9 x VIN Output Voltages
• Delivers Up to 100mA Load Current
• 100kHz to 2.2MHz Adjustable Switching Frequency
Range with External Synchronization
• Configurable Between PFM and Forced-PWM
Modes
● Reduces Power Dissipation
• 22µA No Load Supply Current
• Peak Efficiency > 90%
• PFM Feature for High Light-Load Efficiency
• 1.2μA (typ) Shutdown Current
● Operates Reliably in Adverse Industrial Environments
• Peak Current-Limit Protection
• Built-In Output-Voltage Monitoring with Open-Drain
RESET Pin
• Programmable EN/UVLO Threshold
• Monotonic Startup into Prebiased Output
• Overtemperature Protection
• -40°C to +125°C Industrial/Automotive Temperature
Range
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Ordering Information appears at end of data sheet.
For related parts and recommended products to use with this part, refer
to www.maximintegrated.com/MAX17552.related.
19-6903; Rev 1; 6/14
1 page  
MAX17552
60V, 100mA, Ultra-Small, High-Efficiency
Synchronous Step-Down DC-DC Converter
with 22µA No-Load Supply Current
Typical Operating Characteristics
(VIN = 24V, VGND = 0V, VOUT = 3.3V, VEN/UVLO = 1.5V, RT/SYNC = 191kΩ, CIN = 1μF, TA = +25°C unless otherwise noted)
EFFICIENCY vs.
100
LOAD CURRENT
toc1
90
80
70
60 VIN = 12V VIN = 24V VIN = 36V
50
40
30
20
FIGURE 6 APPLICATION
CIRCUIT, PFM MODE
10 VOUT = 5V
0
1 10 100
LOAD CURRENT (mA)
100
90
80
70
60
50
40
30
20
10
0
0
EFFICIENCY vs.
LOAD CURRENT
toc4
VIN = 12V
VIN = 24V
VIN = 36V
VIN = 6V
VIN = 48V
VIN = 60V
FIGURE 7
APPLICATION CIRCUIT
PWM MODE, VOUT = 3.3V
20 40 60 80
LOAD CURRENT (mA)
100
4.994
4.992
OUTPUT VOLTAGE
vs. LOAD CURRENT
toc7
FIGURE 6 APPLICATION
CIRCUIT, PWM MODE
4.99
4.988
4.986
VIN = 12V VIN = 24V VIN = 36V VIN = 48V
VIN = 60V
4.984
0
20 40 60 80
LOAD CURRENT (mA)
100
100
90
80
70
60
50
40
30
20
10
0
1
EFFICIENCY vs.
LOAD CURRENT
toc2
VIN = 12V VIN = 24V VIN = 36V
FIGURE 7 APPLICATION
CIRCUIT, PFM MODE
VOUT = 3.3V
10
LOAD CURRENT (mA)
100
OUTPUT VOLTAGE
vs. LOAD CURRENT
toc5
FIGURE 6 APPLICATION
5.08 CIRCUIT, PFM MODE
VIN = 12V
5.05
VIN = 36V
5.02 VIN = 48V,60V
VIN = 24V
4.99
4.96
0
20 40 60 80
LOAD CURRENT (mA)
100
OUTPUT VOLTAGE
vs. LOAD CURRENT
3.330
toc8
3.328
FIGURE 7 APPLICATION
CIRCUIT, PWM MODE
3.326
3.324
3.322
3.320
3.318
VIN = 12V VIN = 24V
VIN = 60V
VIN = 48V
VIN = 36V
3.316
0
20 40 60 80
LOAD CURRENT (mA)
100
100
90
80
70
60
50
40
30
20
10
0
0
EFFICIENCY vs.
LOAD CURRENT
toc3
VIN = 12V
VIN = 24V
VIN = 36V
VIN = 48V
VIN = 60V
FIGURE 6 APPLICATION
CIRCUIT, PWM MODE
VOUT = 5V
20 40 60 80
LOAD CURRENT (mA)
100
OUTPUT VOLTAGE
vs. LOAD CURRENT
3.40 toc6
FIGURE 7 APPLICATION
CIRCUIT, PFM MODE
3.38
3.36
3.34
VIN = 12V,
24V
VIN = 36V
VIN = 48V
VIN = 60V
3.32
3.30
0
20 40 60 80
LOAD CURRENT (mA)
100
FEEDBACK VOLTAGE
0.82
VS. TEMPERATURE
toc9
0.81
0.80
0.79
0.78
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
www.maximintegrated.com
Maxim Integrated │ 5
5 Page 
MAX17552
60V, 100mA, Ultra-Small, High-Efficiency
Synchronous Step-Down DC-DC Converter
with 22µA No-Load Supply Current
Detailed Description
The MAX17552 high-efficiency, high-voltage, syn-
chronous step-down DC-DC converter with integrated
MOSFETs operates over a 4V to 60V input voltage range.
The converter can deliver output current up to 100mA at
output voltages of 0.8V to 0.9 x VIN. The output voltage
is accurate to within ±1.75% over -40°C to +125°C. The
converter consumes only 22µA of supply current in PFM
mode while regulating the output voltage at no load.
The device uses an internally compensated, peak-
current-mode control architecture (see the Block
Diagram). On the rising edge of the internal clock, the
high-side p-MOSFET turns on. An internal error amplifier
compares the feedback voltage to a fixed internal refer-
ence voltage and generates an error voltage. The error
voltage is compared to a sum of the current-sense voltage
and a slope-compensation voltage by a PWM comparator
to set the “on-time.” During the on-time of the pMOSFET,
the inductor current ramps up. For the remainder of the
switching period (off-time), the pMOSFET is kept off and
the low-side nMOSFET turns on. During the off-time,
the inductor releases the stored energy as the inductor
current ramps down, providing current to the output.
Under overload conditions, cycle-by-cycle current-limit
feature limits inductor peak current by turning off the high-
side pMOSFET and turning on the low-side nMOSFET.
Mode Selection (MODE)
The device features a MODE pin for selecting either
forced-PWM or PFM mode of operation. If the MODE pin
is left unconnected, the device operates in PFM mode
at light loads. If the MODE pin is grounded, the device
operates in a constant-frequency forced-PWM mode at
all loads. Mode of operation can be changed on-the-fly
during normal operation of the device.
In PWM mode, the inductor current is allowed to go
negative. PWM operation is useful in frequency-sensitive
applications and provides fixed switching frequency at
all loads. However, the PWM mode of operation gives
lower efficiency at light loads compared to PFM mode of
operation.
PFM mode disables negative inductor current and addi-
tionally skips pulses at light loads for high efficiency. In
PFM mode, the inductor current is forced to a fixed peak
of 72mA (typ) (IPFM) every clock cycle until the output
rises to 102% (typ) of the nominal voltage. Once the
output reaches 102% (typ) of the nominal voltage, both
high-side and low-side FETs are turned off and the device
enters hibernate operation until the load discharges the
output to 101% (typ) of the nominal voltage. Most of
the internal blocks are turned off in hibernate operation
to save quiescent current. After the output falls below
101% (typ) of the nominal voltage, the device comes
out of hibernate operation, turns on all internal blocks,
and again commences the process of delivering pulses
of energy to the output until it reaches 102% (typ) of the
nominal output voltage. The device naturally exits PFM
mode when the load current increases to a magnitude of
approximately:
IPFM - (ΔI/2)
where ΔI is the peak-peak ripple current in the output
inductor. The part enters PFM mode again if the load
current reduces to approximately (ΔI/2). See the Inductor
Selection section for details. The advantage of the PFM
mode is higher efficiency at light loads because of lower
current drawn from the supply.
Enable Input (EN/UVLO) and Soft-Start (SS)
When EN/UVLO voltage increases above 1.25V (typ), the
device initiates a soft-start sequence and the duration of
the soft-start depends on the status of the SS pin voltage
at the time of power-up. If the SS pin is not connected,
the device uses a fixed 5ms internal soft-start to ramp
up the internal error-amplifier reference. If a capacitor is
connected from SS to GND, a 5μA current source charges
the capacitor and ramps up the SS pin voltage. The SS
pin voltage is used as reference for the internal error
amplifier. Such a reference ramp up allows the output
voltage to increase monotonically from zero to the final
set value independent of the load current.
EN/UVLO can be used as an input voltage UVLO-
adjustment input. An external voltage-divider between
IN and EN/UVLO to GND adjusts the input voltage at
which the device turns on or turns off. See the Setting
the Input Undervoltage-Lockout Level section for details.
If input UVLO programming is not desired, connect EN/
UVLO to IN (see the Electrical Characteristics table for
EN/UVLO rising and falling-threshold voltages). Driving
EN/UVLO low disables both power MOSFETs, as well as
other internal circuitry, and reduces IN quiescent current
to below 1.2μA. The SS capacitor is discharged with an
internal pulldown resistor when EN/UVLO is low. If the
EN/UVLO pin is driven from an external signal source,
a series resistance of minimum 1kW is recommended to
be placed between the signal source output and the EN/
UVLO pin, to reduce voltage ringing on the line.
www.maximintegrated.com
Maxim Integrated │ 11
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet MAX17552.PDF ] | |
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