MAX1714.pdf

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19-1536; Rev 1; 12/99
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
Features
Ultra-High Efficiency
No Current-Sense Resistor (Lossless I LIMIT )
Quick-PWM with 100ns Load-Step Response
1% V OUT Accuracy Over Line and Load
2.5V/3.3V Fixed or 1V to 5.5V Adjustable Output
Range
2V to 28V Battery Input Range
200/300/450/600kHz Switching Frequency
Overvoltage Protection (MAX1714A)
Undervoltage Protection
Drives Large Synchronous-Rectifier FETs
2V ±1% Reference Output
Ordering Information
PART
MAX1714AEEP
TEMP. RANGE
PIN-PACKAGE
20 QSOP
-40°C to +85°C
MAX1714BEEE
-40°C to +85°C
16 QSOP
Minimal Operating Circuit
BATTERY
4.5V TO 28V
+5V IN PUT
V CC
V DD
Notebook Computers
SHDN
V+
CPU Core Supply
ILIM
BST
Chipset/RAM Supply as Low as 1V
DH
OUTPUT
1.25V TO 2V
1.8V and 2.5V I/O Supply
MAX1714
REF
LX
DL
PGOOD
PGND
(GND)
OUT
FB
SKIP
Quick-PWM is a trademark of Maxim Integrated Products.
† Future product—contact factory for availability.
AGND
(GND)
Pin Configurations appear at end of data sheet.
( ) 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.
1.7ms Digital Soft-Start
Power-Good Indicator
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High-Speed Step-Down Controller
for Notebook Computers
ABSOLUTE MAXIMUM RATINGS
V+ to AGND (Note 1)..............................................-0.3V to +30V
V DD , V CC to AGND (Note 1) .....................................-0.3V to +6V
PGND to AGND (Note 1) ................................................... ±0.3V
SHDN, PGOOD, OUT to AGND (Note 1)..................-0.3V to +6V
ILIM, FB, REF, SKIP,
TON to AGND (Notes 1, 2)....................-0.3V to (V CC + 0.3V)
DL to PGND (Note 1)..................................-0.3V to (V DD + 0.3V)
BST to AGND (Note 1) ...........................................-0.3V to + 36V
DH to LX.....................................................-0.3V to (BST + 0.3V)
LX to BST..................................................................-6V to +0.3V
REF Short Circuit to AGND.........................................Continuous
Continuous Power Dissipation (T A = +70°C)
16-Pin QSOP (derate 8.3mW/°C above +70°C)..........667mW
20-Pin QSOP (derate 9.1mW/°C above +70°C)..........727mW
Operating Temperature Range ..........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range ............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, 4A components from Table 1, V+ = +15V, V CC = V DD = +5V, SKIP = AGND, T A = 0°C to +85°C , unless otherwise
noted.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Input Voltage Range
Battery voltage, V+
2
28
V
V CC, V DD
4.5
5.5
Error Comparator Threshold
(DC Output Voltage Accuracy)
(Note 3)
FB = OUT
0.99
1.0
1.01
V+ = 4.5V to 28V,
SKIP = V CC
FB = AGND
FB = V CC
2.475
2.5
2.525
V
3.267
3.3
3.333
Load Regulation Error
I LOAD = 0 to 3A, SKIP = V CC
V CC = 4.5V to 5.5V, V+ = 4.5V to 28V
9
mV
Line Regulation Error
5
mV
FB Input Bias Current
-0.1
0.1
µA
OUT Input Resistance
FB = AGND
100
190
300
k
Ω
Soft-Start Ramp Time
Rising edge of SHDN to full I LIM
1.7
ms
TON = AGND (600kHz)
140
160
180
V+ = 24V,
V OUT = 2V
(Note 4)
On-Time
TON = REF (450kHz)
175
200
225
ns
TON = unconnected (300kHz)
260
290
320
TON = V CC (200kHz)
380
425
470
Minimum Off-Time
(Note 4)
400
500
ns
Quiescent Supply Current (V CC )
FB forced above the regulation point
550
750
µA
Quiescent Supply Current (V DD )
FB forced above the regulation point
<1
5
µA
Quiescent Supply Current (V+)
25
40
µA
Shutdown Supply Current (V CC )
V SHDN = 0
<1
5
µA
Shutdown Supply Current (V DD )
V SHDN = 0
<1
5
µA
Shutdown Supply Current (V+)
V SHDN = 0 , V+ = 28V, V CC = V DD = 0 or 5V
<1
5
µA
Reference Voltage
V CC = 4.5V to 5.5V, no external REF load
1.98
2
2.02
V
Reference Load Regulation
I REF = 0 to 50µA
0.01
V
REF Sink Current
REF in regulation
10
µA
REF Fault Lockout Voltage
Falling edge, hysteresis = 40mV
1.6
V
2 _______________________________________________________________________________________
323064296.048.png
High-Speed Step-Down Controller
for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, 4A components from Table 1, V+ = +15V, V CC = V DD = +5V, SKIP = AGND, T A = 0°C to +85°C , unless otherwise
noted.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Overvoltage Trip Threshold
With respect to error comparator threshold (MAX1714A only)
10.5
12.5
14.5
%
Overvoltage Fault Propagation
Delay
FB forced 2% above trip threshold (MAX1714A only)
1.5
µs
Output Undervoltage Protection
Threshold
With respect to error comparator threshold
65
70
75
%
Output Undervoltage Protection
Blanking Time
From SHDN signal going high
10
30
ms
Current-Limit Threshold
(Positive Direction, Fixed)
PGND - LX, I LIM = V CC
90
100
110
mV
Current-Limit Threshold
(Positive Direction, Adjustable)
PGND - LX
V ILIM = 0.5V
V ILIM = 2.0V
40
50
60
mV
170
200
230
Current-Limit Threshold
(Negative Direction)
PGND - LX, SKIP = V CC , T A = +25°C,
with respect to positive current-limit threshold
-90
-120
-140
%
Current-Limit Threshold
(Zero Crossing)
PGND - LX, SKIP = AGND
3
mV
PGOOD Propagation Delay
FB forced 2% below PGOOD trip threshold, falling edge
1.5
µs
PGOOD Output Low Voltage
I SINK = 1mA
0.4
V
PGOOD Leakage Current
High state, forced to 5.5V
1
µA
Thermal Shutdown Threshold
Hysteresis = 10°C
150
°C
V CC Undervoltage Lockout
Threshold
Rising edge, hysteresis = 20mV,
PWM disabled below this level
4.1
4.4
V
DH Gate-Driver On-Resistance
BST - LX forced to 5V
1.5
5
Ω
DL Gate-Driver On-Resistance
(Pull-Up)
DL, high state
1.5
5
Ω
DL Gate-Driver On-Resistance
(Pull-Down)
DL, low state
0.5
1.7
Ω
DH Gate-Driver Source/Sink
Current
DH forced to 2.5V, BST - LX forced to 5V
1
A
DL Gate-Driver Source Current
DL forced to 2.5V
1
A
DL Gate-Driver Sink Current
DL forced to 2.5V
3
A
Dead Time
DL rising
35
ns
DH rising
26
SKIP Input Current Logic
Threshold
To disable overvoltage and undervoltage fault detection,
T A = +25°C
-1.5
-0.1
mA
PGOOD Trip Threshold
Measured at FB with respect to error comparator
threshold, falling edge
-8
-6
-4
%
Logic Input High Voltage
SHDN, SKIP
2.4
V
Logic Input Low Voltage
SHDN, SKIP
0.8
V
Logic Input Current
SHDN, SKIP
-1
1
µA
ILIM Input Current
SHDN, SKIP
± 10
nA
_______________________________________________________________________________________ 3
323064296.049.png
High-Speed Step-Down Controller
for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, 4A components from Table 1, V+ = +15V, V CC = V DD = +5V, SKIP = AGND, T A = 0°C to +85°C , unless otherwise
noted.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
TON V CC Level
V CC - 0.4
V
TON Float Voltage
3.15
3.85
V
TON Reference Level
1.65
2.35
V
TON AGND Level
0.5
V
TON Input Current
Forced to AGND or V CC
-3
3
µA
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, 4A components from Table 1, V+ = 15V, V CC = V DD = +5V, SKIP = AGND, T A = -40°C to +85°C , unless other-
wise noted.) (Notes 1, 5)
PARAMETER
CONDITIONS
MIN
TYP
MAX UNITS
Input Voltage Range
Battery voltage, V+
2
28
V
V CC, V DD
4.5
5.5
Error Comparator Threshold
(DC Output Voltage Accuracy)
(Note 3)
FB = OUT
0.985
1.015
V+ = 4.5V to 28V,
SKIP = V CC
FB = AGND
2.462
2.538
V
FB = V DD
3.25
3.35
TON = AGND (600kHz)
140
180
V+ = 24V,
V OUT = 2V
(Note 4)
On-Time
TON = REF (450kHz)
175
225
ns
TON = unconnected (300kHz)
260
320
TON = V CC (200kHz)
380
470
Minimum Off-Time
(Note 4)
500
ns
Quiescent Supply Current (V CC )
FB forced above the regulation point
750
µA
Reference Voltage
V CC = 4.5V to 5.5V, no external REF load
1.98
2.02
V
Overvoltage Trip Threshold
With respect to error comparator threshold
(MAX1714A only)
10
15
%
Output Undervoltage
Protection Threshold
With respect to error comparator threshold
65
75
%
Current-Limit Threshold (Positive
Direction, Fixed)
PGND - LX, ILIM = V CC
85
115
mV
Current-Limit Threshold
(Positive Direction, Adjustable)
PGND - LX
V ILIM = 0.5V
35
65
mV
V ILIM = 2.0V
160
240
V CC Undervoltage Lockout
Threshold
Rising edge, hysteresis = 20mV, PWM disabled below
this level
4.1
4.4
V
Logic Input High Voltage
SHDN, SKIP
2.4
V
Logic Input Low Voltage
SHDN, SKIP
0.8
V
Logic Input Current
SHDN, SKIP
-1
1
µA
4 _______________________________________________________________________________________
323064296.051.png
High-Speed Step-Down Controller
for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, 4A components from Table 1, V+ = +15V, V CC = V DD = +5V, SKIP = AGND, T A = -40°C to +85°C , unless other-
wise noted.) (Notes 1, 5)
PARAMETER
CONDITIONS
Measured at FB with respect to error comparator
threshold, falling edge
MIN
TYP
MAX
UNIT
PGOOD Trip Threshold
-8
-4
%
PGOOD Output Low Voltage
I SINK = 1mA
0.4
V
PGOOD Leakage Current
High state, forced to 5.5V
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, V BST = 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, V IN = +15V, SKIP = AGND, TON = unconnected, T A = +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
(4A COMPONENTS, V OUT = 2.5V, 300kHz)
EFFICIENCY vs. LOAD CURRENT
(8A COMPONENTS, V OUT = 1.6V, 300kHz)
EFFICIENCY vs. LOAD CURRENT
(1.5A COMPONENTS, V OUT = 2.5V,
TON = GND, 600kHz)
100
100
V IN = 7V
100
V IN = 5V
V IN = 7V
90
90
90
80
80
V IN = 12V
V IN = 20V
80
V IN = 20V
70
V IN = 12V
70
70
60
60
60
0.01
0.1
1
10
0.01
0.1
1
10
0.01
0.1
1
10
LOAD CURRENT (A)
LOAD CURRENT (A)
LOAD CURRENT (A)
_______________________________________________________________________________________ 5
323064296.052.png

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