Datenblatt-pdf.com


MAX20745 Schematic ( PDF Datasheet ) - Maxim Integrated

Teilenummer MAX20745
Beschreibung Step-Down Switching Regulator
Hersteller Maxim Integrated
Logo Maxim Integrated Logo 




Gesamt 26 Seiten
MAX20745 Datasheet, Funktion
MAX20745
EVALUATION KIT AVAILABLE
Integrated, Step-Down Switching Regulator
General Description
The MAX20745 is a fully integrated, highly efficient
switching regulator for applications operating from 4.5V to
16V and requiring up to 25A maximum load. This single-
chip regulator provides extremely compact, high-efficien-
cy power-delivery solutions with high-precision output
voltages and excellent transient response for networking,
datacom, and telecom equipment.
The IC offers a broad range of programmable features
through capacitors and resistors connected to dedicated
programming pins. Using this feature, the operation can
be optimized for a specific application, reducing the
component count- and/or setting-appropriate trade-offs
between the regulator's performance and system cost.
Ease of programming enables using the same design for
multiple applications.
The MAX20745 includes protection capabilities. Positive
and negative cycle-by-cycle overcurrent protection and
overtemperature protection ensure a rugged design. Input
undervoltage lockout shuts down the device to prevent
operation when the input voltage is out of specification. A
status pin provides an output signal to show that the out-
put voltage is within range and the system is regulating.
Applications
● Communications Equipment
● Networking Equipment
● Servers and Storage Equipment
● Point-of-Load Voltage Regulators
μP Chipsets
● Memory VDDQ
● I/O
DESCRIPTION
CURRENT INPUT
RATING* VOLTAGE
OUTPUT
VOLTAGE
Electrical rating
25A
4.5V to 16V
0.6484V
to 5.5V
Thermal rating,
TA = 55°C, 200LFM
Thermal rating,
TA = 85°C, 0LFM
25A
15A
12V
12V
1V
1V
*For specific operating conditions, refer to the SOA curves in
the Typical Operating Characteristics section.
Benefits and Features
● High Power Density and Low Component Count
• Overall Solution Size: 509mm2 Including Inductor
and Output Capacitors
90.8% Peak Efficiency: VDDH = 12V and
VOUT = 1V
Fast Transient Response: Supports Up to 300A/μs
Load-Step Transients
● Optimized Component Performance and Efficiency
with Reduced Design-In Time
● Increased Power-Supply Reliability with System and
IC Self-Protection Features
• Differential Remote Sense with Open-Circuit
Detection
• Hiccup Overcurrent Protection
• Programmable Thermal Shutdown
Typical System Efficiency vs.
Load Current (VDDH = 12V)
100
95
90
85
80
75
70
65
60
55
50
0
VoVutO=U5TV= 5V
VoVutO=U3T.3=V 3.3V
VoVutO=U1T.8=V 1.8V
VoVutO=U1T.2=V 1.2V
VoVutO=U1TV= 1V
VoVutO=U0T.8=V 0.8V
VoVutO=U0T.6=5V0.65V
5 10 15 20 25
IOUT (A)
Ordering Information appears at end of data sheet.
19-8588; Rev 0; 10/16






MAX20745 Datasheet, Funktion
MAX20745
Integrated, Step-Down Switching Regulator
Typical Operating Characteristics
(Unless otherwise noted: Tested on the MAX20745EVKIT# with component values per Table 8; VDDH = 12V, VOUT = 1V, fSW = 400kHz,
TA = 25°C, Still Air, No Heatsink.)
STARTUP RESPONSE
toc01
TRANSIENT RESPONSE
toc02
VOUTN
VINSIDE
VBACKUP
VX (20V/div)
STAT(2V/div)
OE (2V/div)
VOUT (200mV/div)
VOUTN
VOUT (20mV/div)
VINSIDE
VBACKUP
TIME: 500µs/div
TIME: 100µs/div
CONDITIONS: IOUT = 15A to 22.5A STEP at 1A/µs
TYPICAL VOUT RIPPLE
toc03
VOUTN
VINSIDE
VOUT (20mV/div)
VBACKUP
VX (5V/div)
TIME: 2µs/div
CONDITIONS: IOUT = 25A
www.maximintegrated.com
Maxim Integrated 6

6 Page









MAX20745 pdf, datenblatt
MAX20745
Integrated, Step-Down Switching Regulator
Block Diagram
STAT
OE
PGM1
PGM2
PGM3
VCC
VCC2
VCC3
AGND
DIGITAL
CONTROL
MUX
VCC
TELEMETRY
tON
TIMER
R
Q
S
VCC
LDO
POWER
SWITCHING
OCP CURRENT
SENSE
VDDH
BST
VX
GND
PWM
ERROR
AMPLIFIER
VCC CURRENT
DAC
REFERENCE VOLTAGE AND SOFT START
VSENSE+
VSENSE-
Operation
Control Architecture
The MAX20745 provides an extremely compact, high-
efficiency regulator solution with minimal external compo-
nents and circuit design required. The monolithic solution
includes the top and bottom power switches, gate drives,
precision DAC reference, PWM controller, and fault pro-
tections (see the Block Diagram). An external bootstrap
capacitor is used to provide the drive voltage for the top
switch. Other external components include the input and
output filter capacitors, buck inductor, and a few Rs and
Cs to set the operating mode.
The IC implements an advanced valley current-mode
control algorithm that supports all multilayer ceramic chip
(MLCC) output capacitors and fast transient response. In
steady-state, it operates at a fixed switching frequency.
During loading transients, the switching frequency speeds
up to minimize the output-voltage undershoot. Likewise,
during unloading transients, the switching frequency
slows down to minimize the output-voltage overshoot.
The switching frequency can be set to 400kHz, 500kHz,
600kHz, 700kHz, 800kHz, or 900kHz using C_SEL2 and
C_SEL3.
Voltage regulation is achieved by modulating the low-side
on-time, comparing the difference between the feedback
and reference voltages with the low-side current-sense
signal using Maxim's proprietary integrated current-sense
technology. Once the PWM modulator forces a low-to-
high transition, the high-side switch is enabled for a fixed
time after which the low-side switch is turned on again. An
error amplifier with an integrator is used to maintain zero-
droop operation. The integrator has a transient recovery
time constant of 20µs (typ).
During regulation, the differential voltage between the
VSENSE+ and VSENSE- pins tracks the reference voltage
which can be set to 0.6484V, 0.8984V or 1V via C_SEL1.
The sense pins can be connected to the output voltage
through a voltage divider so VOUT can be higher than the
reference voltage.
The switching frequency is determined by the high-side
ontime as shown in Equation 1.
Equation 1:
=fSW
1 × VOUT
t H_ON VDDH
where:
fSW = Switching frequency (MHz)
tH_ON = On period for high-side switch (μs)
VOUT = Output voltage (V)
VDDH = Input voltage (V)
www.maximintegrated.com
Maxim Integrated 12

12 Page





SeitenGesamt 26 Seiten
PDF Download[ MAX20745 Schematic.PDF ]

Link teilen




Besondere Datenblatt

TeilenummerBeschreibungHersteller
MAX20745Step-Down Switching RegulatorMaxim Integrated
Maxim Integrated

TeilenummerBeschreibungHersteller
CD40175BC

Hex D-Type Flip-Flop / Quad D-Type Flip-Flop.

Fairchild Semiconductor
Fairchild Semiconductor
KTD1146

EPITAXIAL PLANAR NPN TRANSISTOR.

KEC
KEC


www.Datenblatt-PDF.com       |      2020       |      Kontakt     |      Suche