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PDF MAX1854 Data sheet ( Hoja de datos )
| Número de pieza | MAX1854 | |
| Descripción | High-Speed / Adjustable / Synchronous Step-Down Controllers with Integrated Voltage Positioning | |
| Fabricantes | Maxim Integrated | |
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19-1758; Rev 0; 8/00
High-Speed, Adjustable, Synchronous Step-Down
Controllers with Integrated Voltage Positioning
General Description
The MAX1716/MAX1854/MAX1855 step-down con-
trollers are intended for core CPU DC-DC converters in
notebook computers. They feature a dynamically
adjustable output (5-bit DAC), ultra-fast transient
response, high DC accuracy, and high efficiency need-
ed for leading-edge CPU core power supplies. 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 relative-
ly constant switching frequency.
The MAX1716/MAX1854/MAX1855 are designed
specifically for CPU core applications requiring a volt-
age-positioned supply. The voltage-positioning input
(VPS), combined with a high DC accuracy control loop,
is used to implement a power supply that modifies its
output set point in response to the load current. This
arrangement decreases full-load power dissipation and
reduces the required number of output capacitors.
The 28V input range of the MAX1716/MAX1854/MAX1855
enables single-stage buck conversion from high-volt-
age batteries for the maximum possible efficiency.
Alternatively, the devices’ high-frequency capability
combined with two-stage conversion (stepping down
the +5V system supply instead of the battery) allows
the smallest possible physical size. The output voltage
can be dynamically adjusted through the 5-bit digital-
to-analog converter (DAC) inputs.
The MAX1716/MAX1854/MAX1855 are available in a
24-pin QSOP package. For applications requiring
SpeedStep™ power control (see the MAX1717).
________________________Applications
Notebook Computers
Docking Stations
CPU Core Supply
Single-Stage (BATT to VCORE) Converters
Two-Stage (+5V to VCORE) Converters
PART
MAX1716EEG
MAX1854EEG
MAX1855EEG
Ordering Information
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
24 QSOP
24 QSOP
24 QSOP
Features
o High-Efficiency Voltage Positioning
o Quick-PWM Architecture
o ±1% VOUT Line-Regulation Accuracy
o Adjustable Output Range (5-Bit DAC)
MAX1716: 0.925V to 1.6V
MAX1854: 0.925V to 2.0V
MAX1855: 0.600V to 1.75V
o 2V to 28V Input Range
o 200/300/400/550kHz Switching Frequency
o Output Undervoltage Protection
o Overvoltage Protection (MAX1716/MAX1855)
o Drive Large Synchronous-Rectifier MOSFETs
o 1.7ms Digital Soft-Start
o 700µA ICC Supply Current
o 1µA Shutdown Supply Current
o 2V ±1% Reference Output
o VGATE Transition-Complete Indicator
o Small 24-Pin QSOP Package
+5V INPUT
DAC
INPUTS
Typical Operating Circuit
BATTERY
2V TO 28V
VCC
SHDN
ILIM
REF
VDD
V+
BST
DH
MAX1716
CC MAX1854 LX
SKIP MAX1855 DL
GND CS
TON VPS
D0
D1 PGND
D2
D3 FB
D4 VGATE
OUTPUT
Quick-PWM is a trademark of Maxim Integrated Products.
SpeedStep is a trademark of Intel Corp.
Pin Configuration appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
1 page  
High-Speed, Adjustable, Synchronous Step-Down
Controllers with Integrated Voltage Positioning
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V+ = +15V, VCC = VDD = 5V, SKIP = VCC, VPS = PGND, TA = -40°C to +85°C, unless otherwise noted.) (Note 6)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX UNITS
PWM CONTROLLER
Input Voltage Range
Battery voltage, V+
VCC, VDD
2 28
V
4.5 5.5
DC Output Voltage Accuracy
(Notes 2, 3)
V+ = 4.5V to 28V,
VPS = PGND
DAC codes from
1.35V to 2.0V
DAC codes from
0.6V to 1.3V
-1.6
-2
1.6
%
2
FB Input Bias Current
VPS Input Bias Current
VPS Gain
CS Input Bias Current
ILIM Input Leakage Current
IFB
IVPS
AVPS
ICS
IILIM
FB = 0.6V to 2.0V
VVPS = ±40mV
VVPS = 0 or -40mV, gain from VPS to FB
0 to 28V
VILIM = 0 or 5.0V
TON = GND
-0.2
-1
0.153
-1
205
0.2
1
0.197
1
100
300
µA
µA
%/mV
µA
nA
On-Time (Note 4)
tON
V+ = 11.0V,
VFB = 1.5V
TON = REF
TON = open
280
425
375
ns
520
Minimum Off-Time (Note 4)
BIAS AND REFERENCE
tOFF(MIN)
TON = VCC 615 740
500 ns
Quiescent Supply Current (VCC)
ICC
Measured at VCC, FB forced above the
regulation point
950 µA
Quiescent Supply Current (VDD)
Quiescent Supply Current (V+)
Shutdown Supply Current (VCC)
Shutdown Supply Current (VDD)
Shutdown Supply Current (V+)
Reference Voltage
Reference Load Regulation
REF Sink Current
FAULT PROTECTION
Output Overvoltage Fault
Threshold (Note 5)
IDD
I+
VREF
IREF
Measured at VDD, FB forced above the
regulation point
SHDN = GND
SHDN = GND
SHDN = GND, V+ = 28V, VCC = VDD = 0 or 5V
VCC = 4.5V to 5.5V, no external REF load
IREF = 0 to 50µA
REF in regulation
Measured at FB
MAX1716
MAX1855
1.98
10
1.8
1.97
5
40
5
5
5
2.02
0.01
2.0
2.03
µA
µA
µA
µA
µA
V
V
µA
V
Output Undervoltage Fault
Threshold (Foldback)
35 45 %
Output Undervoltage Fault
Blanking Time (Foldback)
From SHDN signal going high
10 30 ms
_______________________________________________________________________________________ 5
5 Page 
High-Speed, Adjustable, Synchronous Step-Down
Controllers with Integrated Voltage Positioning
Typical Operating Characteristics (continued)
(Circuit from Figure 1, components from Table 2, TA = +25°C, unless otherwise noted.)
SHORT-CIRCUIT WAVEFORM
2V MAX1716-30
A
1V
0
20A
10A B
0
5V
C
0
20µs/div
A. VOUT = 1.6V, 1V/div
B. IL, L = 0.68µH, 10A/div
C. SHORT-CIRCUIT CONTROL, 5V/div
STARTUP WAVEFORM
(18A LOAD)
2V MAX1716-31
1V A
0
20A
10A B
0
5V
C
0
200µs/div
A. VOUT = 1.6V, 1V/div
B. IL, L = 0.68µH, 10A/div
C. VSHDN = 0 TO VCC, 5V/div
ROUT = 88mΩ
SHUTDOWN WAVEFORM
2V MAX1716-32
A
0
20A
0B
-20A
5V
C
0
5V
0
100µs/div
A. VOUT = 1.6V, ROUT = 88mΩ, 2V/div
B. IL, L = 0.68µH, 20A/div
C. VDL, 5V/div
D. VSHDN = VCC TO 0, 5V/div
D
STARTUP WAVEFORM
(NO-LOAD)
2V MAX1716-33
1V A
0
10A
B
0
5V
C
0
5V
0
100µs/div
A. VOUT = 1.6V, NO LOAD, 1V/div
B. IL, L = 0.68µH, 10A/div
C. VDL, 5V/div
D. VSHDN = 0 TO VCC, 5V/div
D
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet MAX1854.PDF ] | |
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