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PDF MAX1714 Data sheet ( Hoja de datos )
| Número de pieza | MAX1714 | |
| Descripción | High-Speed Step-Down Controller for Notebook Computers | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-1536; Rev 1; 12/99
EVAFLOULALTOIWONDKAITTAMSAHNEUEATLS
High-Speed Step-Down Controller
for Notebook Computers
General Description
The MAX1714 pulse-width modulation (PWM) controller
provides the high efficiency, excellent transient
response, and high DC output accuracy needed for
stepping down high-voltage batteries to generate low-
voltage CPU core or chip-set/RAM supplies in notebook
computers.
Maxim’s proprietary Quick-PWM™ quick-response,
constant-on-time PWM control scheme handles wide
input/output voltage ratios with ease and provides
100ns “instant-on” response to load transients while
maintaining a relatively constant switching frequency.
The MAX1714 achieves high efficiency at a reduced
cost by eliminating the current-sense resistor found in
traditional current-mode PWMs. Efficiency is further
enhanced by an ability to drive very large synchronous-
rectifier MOSFETs.
Single-stage buck conversion allows these devices to
directly step down high-voltage batteries for the highest
possible efficiency. Alternatively, two-stage conversion
(stepping down the +5V system supply instead of the
battery) at a higher switching frequency allows the mini-
mum possible physical size.
The MAX1714 is intended for CPU core, chipset,
DRAM, or other low-voltage supplies as low as 1V. The
MAX1714A is available in a 20-pin QSOP package and
includes overvoltage protection. The MAX1714B is
available in a 16-pin QSOP package with no overvolt-
age protection. For applications requiring VID compli-
ance or DAC control of output voltage, refer to the
MAX1710/MAX1711 data sheet. For a dual output ver-
sion, refer to the MAX1715† data sheet.
Applications
Notebook Computers
CPU Core Supply
Chipset/RAM Supply as Low as 1V
1.8V and 2.5V I/O Supply
Quick-PWM is a trademark of Maxim Integrated Products.
† Future product—contact factory for availability.
Pin Configurations appear at end of data sheet.
Features
o Ultra-High Efficiency
o No Current-Sense Resistor (Lossless ILIMIT)
o Quick-PWM with 100ns Load-Step Response
o 1% VOUT Accuracy Over Line and Load
o 2.5V/3.3V Fixed or 1V to 5.5V Adjustable Output
Range
o 2V to 28V Battery Input Range
o 200/300/450/600kHz Switching Frequency
o Overvoltage Protection (MAX1714A)
o Undervoltage Protection
o 1.7ms Digital Soft-Start
o Drives Large Synchronous-Rectifier FETs
o 2V ±1% Reference Output
o Power-Good Indicator
PART
MAX1714AEEP
MAX1714BEEE
Ordering Information
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 QSOP
16 QSOP
Minimal Operating Circuit
+5V INPUT
VCC
SHDN
VDD
V+
BATTERY
4.5V TO 28V
ILIM BST
DH
MAX1714
LX
REF
DL
PGOOD PGND
(GND)
FB OUT
SKIP
AGND
(GND)
OUTPUT
1.25V TO 2V
( ) ARE FOR THE MAX1714B ONLY.
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
1 page  
High-Speed Step-Down Controller
for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, 4A components from Table 1, V+ = +15V, VCC = VDD = +5V, SKIP = AGND, TA = -40°C to +85°C, unless other-
wise noted.) (Notes 1, 5)
PARAMETER
CONDITIONS
MIN TYP MAX UNIT
PGOOD Trip Threshold
Measured at FB with respect to error comparator
threshold, falling edge
-8
-4 %
PGOOD Output Low Voltage
PGOOD Leakage Current
ISINK = 1mA
High state, forced to 5.5V
0.4 V
1 µA
Note 1: For the MAX1714B, AGND and PGND refer to a single pin designated GND.
Note 2: SKIP may be forced below -0.3V, temporarily exceeding the absolute maximum rating, disabling over/undervoltage fault
detection for the purpose of debugging prototypes (Figure 6). Limit the current drawn to 5mA maximum.
Note 3: When the inductor is in continuous conduction, the output voltage will have a DC regulation level higher than the error-
comparator threshold by 50% of the ripple. In discontinuous conduction (SKIP = AGND, light-loaded), the output voltage
will have a DC regulation level higher than the trip level by approximately 1.5% due to slope compensation.
Note 4: On-time and off-time specifications are measured from 50% point to 50% point at the DH pin with LX = PGND, VBST = 5V,
and a 250pF capacitor connected from DH to LX. Actual in-circuit times may differ due to MOSFET switching speeds.
Note 5: Specifications to -40°C are guaranteed by design, not production tested.
__________________________________________Typical Operating Characteristics
(Circuit of Figure 1, components from Table 1, VIN = +15V, SKIP = AGND, TON = unconnected, TA = +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
(4A COMPONENTS, VOUT = 2.5V, 300kHz)
100
VIN = 7V
90
EFFICIENCY vs. LOAD CURRENT
(8A COMPONENTS, VOUT = 1.6V, 300kHz)
100
VIN = 7V
90
EFFICIENCY vs. LOAD CURRENT
(1.5A COMPONENTS, VOUT = 2.5V,
TON = GND, 600kHz)
100
VIN = 5V
90
80
80
VIN = 12V VIN = 20V
80
VIN = 20V
70 VIN = 12V
70
70
60
0.01
0.1 1
LOAD CURRENT (A)
60
10 0.01
0.1 1
LOAD CURRENT (A)
60
10 0.01 0.1
1
LOAD CURRENT (A)
10
_______________________________________________________________________________________ 5
5 Page 
High-Speed Step-Down Controller
for Notebook Computers
IN
2V TO 28V
V+ ILIM
TON ON-TIME FROM
COMPUTE OUT
TON
TRIG Q
1-SHOT
SKIP
SHDN
REF
MAX1714A ONLY
REF REF
-6% +12%
PGOOD
OVP/UVLO
LATCH
S1
S2
Q
TOFF
1-SHOT
Q TRIG
MAX1714
+5V
9R
R
BST
SQ
R
ERROR
AMP
REF
-30%
TIMER
CURRENT
LIMIT
Σ
DH
LX
S
Q
R
x2
ZERO CROSSING
VDD +5V
DL
(MAX1714B ONLY)
PGND
(GND)
OUT
CHIP
SUPPLY
VCC
FEEDBACK
MUX
(SEE FIGURE 9)
2V REF
REF
(GND)
AGND
FB
OUTPUT
+5V
NOTE: IN THE MAX1714B, AGND AND PGND ARE INTERNALLY CONNECTED TO THE GND PIN.
( ) ARE FOR THE MAX1714B ONLY.
Figure 2. MAX1714 Functional Diagram
On-Time One-Shot (TON)
The heart of the PWM core is the one-shot that sets the
high-side switch on-time. This fast, low-jitter, adjustable
one-shot includes circuitry that varies the on-time in
response to battery and output voltage. The high-side
switch on-time is inversely proportional to the battery
voltage as measured by the V+ input, and proportional
to the output voltage. This algorithm results in a nearly
constant switching frequency despite the lack of a fixed-
frequency clock generator. The benefits of a constant
switching frequency are twofold: first, the frequency can
be selected to avoid noise-sensitive regions such as the
455kHz IF band; second, the inductor ripple-current
operating point remains relatively constant, resulting in
easy design methodology and predictable output volt-
age ripple.
On-Time = K (VOUT + 0.075V) / VIN
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet MAX1714.PDF ] | |
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