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PDF ADP1878 Data sheet ( Hoja de datos )
| Número de pieza | ADP1878 | |
| Descripción | Synchronous Buck Controller | |
| Fabricantes | Analog Devices | |
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Data Sheet
Synchronous Buck Controller with
Constant On Time and Valley Current Mode
ADP1878/ADP1879
FEATURES
Power input voltage range: 2.95 V to 20 V
On-board bias regulator
Minimum output voltage: 0.6 V
0.6 V reference voltage with ±1.0% accuracy
Supports all N-channel MOSFET power stages
Available in 300 kHz, 600 kHz, and 1.0 MHz options
No current sense resistor required
Power saving mode (PSM) for light loads (ADP1879 only)
Resistor programmable current limit
Power good with internal pull-up resistor
Externally programmable soft start
Thermal overload protection
Short-circuit protection
Standalone precision enable input
Integrated bootstrap diode for high-side drive
Starts into a precharged output
Available in a 14-lead LFCSP_WD package
APPLICATIONS
Telecommunications and networking systems
Mid-to-high end servers
Set-top boxes
DSP core power supplies
GENERAL DESCRIPTION
The ADP1878/ADP1879 are versatile current-mode, synchronous
step-down controllers. They provide superior transient response,
optimal stability, and current-limit protection by using a constant
on time, pseudo fixed frequency with a programmable current-limit,
current control scheme. These devices offer optimum performance
at low duty cycles by using a valley, current-mode control architec-
ture allowing the ADP1878/ADP1879 to drive all N-channel power
stages to regulate output voltages to as low as 0.6 V.
The ADP1879 is the power saving mode (PSM) version of the
device and is capable of pulse skipping to maintain output
regulation while achieving improved system efficiency at light
loads (see the ADP1879 Power Saving Mode (PSM) section for
more information).
Available in three frequency options (300 kHz, 600 kHz, and
1.0 MHz) plus the PSM option, the ADP1878/ADP1879 are well
suited for a wide range of applications that require a single input
power supply range from 2.95 V to 20 V. Low voltage biasing is
supplied via a 5 V internal low dropout regulator (LDO). In
addition, soft start programmability is included to limit input
inrush current from the input supply during startup and to
provide reverse current protection during precharged output
Rev. A
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
TYPICAL APPLICATIONS CIRCUIT
VIN = 2.95V TO 20V
CC
RC CC2
VREG
VOUT
10kΩ
RTOP
RBOT
CVREG2
CVREG
RRES
VIN
ADP1878/
ADP1879
COMP
BST
EN
FB
GND
VREG
DRVH
SW
DRVL
RES
PGOOD
SS
PGND
CIN
CBST
Q1 L
COUT
Q2
RPGD
VEXT
CSS
VOUT
LOAD
Figure 1.
conditions. The low-side current sense, current gain scheme and
integration of a boost diode, together with the PSM/forced
pulse-width modulation (PWM) option, reduce the external
device count and improve efficiency.
The ADP1878/ADP1879 operate over the −40°C to +125°C
junction temperature range and are available in a 14-lead
LFCSP_WD package.
100
95 VIN = 5V (PSM)
90
85
80
75
70 VIN = 16.5V
65
60 VIN = 13V
55 VIN = 13V (PSM)
50
45
40 VIN = 16.5V (PSM)
35
30
25
10
100
TA = 25°C
fVSOWUT=
= 1.8V
300kHz
WÜRTH INDUCTOR:
744325120, L = 1.2µH, DCR = 1.8mΩ
INFINEON FETs:
BSC042N03MS G (UPPER/LOWER)
1k 10k 100k
LOAD CURRENT (mA)
Figure 2. ADP1878/ADP1879 Efficiency vs. Load Current (VOUT = 1.8 V, 300 kHz)
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©2011–2012 Analog Devices, Inc. All rights reserved.
1 page  
Data Sheet
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
VREG to PGND, GND
VIN, EN, PGOOD to PGND
FB, COMP, RES, SS to GND
DRVL to PGND
SW to PGND
BST to SW
BST to PGND
DRVH to SW
PGND to GND
PGOOD Input Current
θJA (14-Lead LFCSP_WD)
4-Layer Board
Operating Junction Temperature Range
Storage Temperature Range
Soldering Conditions
Maximum Soldering Lead Temperature
(10 sec)
Rating
−0.3 V to +6 V
−0.3 V to +28 V
−0.3 V to (VREG + 0.3 V)
−0.3 V to (VREG + 0.3 V)
−2.0 V to +28 V
−0.6 V to (VREG + 0.3 V)
−0.3 V to +28 V
−0.3 V to VREG
±0.3 V
35 mA
30°C/W
−40°C to +125°C
−65°C to +150°C
JEDEC J-STD-020
300°C
Stresses a bove those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Absolute maximum ratings apply individually only, not in
combination. Unless otherwise specified, all other voltages are
referenced to PGND.
ADP1878/ADP1879
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Boundary Condition
In determining the values given in Table 2 and Table 3, natural
convection is used to transfer heat to a 4-layer evaluation board.
Table 3. Thermal Resistance
Package Type
θJA (14-Lead LFCSP_WD)
4-Layer Board
θJA Unit
30 °C/W
ESD CAUTION
Rev. A | Page 5 of 40
5 Page 
Data4heet
338
VIN = 13V
+125°C
334
VIN = 16.5V
+25°C
–40°C
330
326
322
318
314
310
306
302
298
0
800 1600 2400 3200 4000 4800 5600 6400 7200 8000 8800
LOAD CURRENT (mA)
Figure 28. Frequency vs. Load Current, 300 kHz, VOUT = 7 V
540 VIN = 13V
+125°C
VIN = 16.5V
+25°C
–40°C
510
480
450
420
390
360
330
300
0
1200 2400 3600 4800 6000 7200 8400 9600 10,800 12,000
LOAD CURRENT (mA)
Figure 29. Frequency vs. Load Current, 600 kHz, VOUT = 0.8 V
675
VIN = 13V
655 VIN = 16.5V
635
615
595
575
555
535
515
495
0
+125°C
+25°C
–40°C
1000 2000 3000 4000 5000 6000 7000 8000 9000 10,000
LOAD CURRENT (mA)
Figure 30. Frequency vs. Load Current, 600 kHz, VOUT = 1.8 V
ADP1878/ADP1879
740
733
726
719
712
705
698
691
684
677
670
663
656
649
642
635
628
621
0
VIN = 13V
VIN = 16.5V
+125°C
+25°C
–40°C
800 1600 2400 3200 4000 4800 5600 6400 7200 8000 8800 9600
LOAD CURRENT (mA)
Figure 31. Frequency vs. Load Current, 600 kHz, VOUT = 5 V
850
VIN = 13V
+125°C
VIN = 16.5V
+25°C
–40°C
775
700
625
550
475
400
0
2000
4000
6000
8000 10,000 12,000
LOAD CURRENT (mA)
Figure 32. Frequency vs. Load Current, VOUT = 1.0 MHz, 0.8 V
1225
1150
1075
VIN = 13V
VIN = 16.5V
+125°C
+25°C
–40°C
1000
925
850
775
700
625
550
0
1200 2400 3600 4800 6000 7200 8400 9600 10,800 12,000
LOAD CURRENT (mA)
Figure 33. Frequency vs. Load Current, 1.0 MHz, VOUT = 1.8 V
Rev. A | Page 11 of 40
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet ADP1878.PDF ] | |
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