General Description
The MAX1992/MAX1993 pulse-width modulation (PWM)
controllers provide high-efficiency, excellent transient
response, and high DC output accuracy. The devices
step down high-voltage batteries to generate low-
voltage CPU core or chipset/RAM supplies in notebook
computers.
Maxim's proprietary Quick-PWMTM quick-response, con-
stant 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. Efficiency is
enhanced by the ability to drive very large synchronous-
rectifier MOSFETs. Current sensing to ensure reliable
overload and inductor saturation protection is available
using an external current-sense resistor in series with the
output. Alternatively, the controller can sense the current
across the synchronous rectifier alone or use lossless
inductor sensing for lowest power dissipation.
Single-stage buck conversion allows the MAX1992/
MAX1993 to directly step down high-voltage batteries for
the highest possible efficiency. Alternatively, two-stage
conversion (stepping down from another system supply
rail instead of the battery) at the maximum switching fre-
quency allows the minimum possible physical size.
The MAX1992 powers the CPU core, chipset, DRAM, or
other supply rails as low as 0.7V. The MAX1993 powers
chipsets and graphics processor cores, which require
dynamically adjustable output voltages. The MAX1993
provides a tracking input that can be used for active ter-
mination buses. The MAX1992/MAX1993 are available in
a 24-pin thin QFN package with optional overvoltage and
undervoltage protection.
For dual step-down PWM controllers with inductor satu-
ration protection, external reference input voltage, and
dynamically selectable output voltages, refer to the
MAX1540/MAX1541 data sheet.
Applications
Notebook Computers
Core/IO Supplies as Low as 0.7V
1.8V and 2.5V Supplies
DDR Memory Termination (MAX1993)
Active Termination Buses (MAX1993)
CPU/Chipset/GPU with Dynamic Voltage Cores
(MAX1993)
Features
o
Inductor Saturation Protection
o
Accurate Current Limit
o
Ultra-High Efficiency
o
Quick-PWM with 100ns Load-Step Response
o
MAX1992
1.8V/2.5V Fixed or 0.7V to 5.5V Adjustable
Output Range
o
MAX1993
External Reference Input
Dynamically Selectable Output Voltage
(0.7V to 5.5V)
Optional Power-Good and Fault Blanking
During Transitions
o
±1% V
OUT
Accuracy Over Line and Load
o
2V to 28V Battery Input Range (V
IN
)
o
200/300/450/600kHz Switching Frequency
o
Overvoltage/Undervoltage Protection Option
o
1.7ms Digital Soft-Start
o
Drives Large Synchronous Rectifier FETs
o
2V ±0.7% Reference Output
o
Power-Good Window Comparator
MAX1992/MAX1993
Quick-PWM Step-Down Controllers with Inductor
Saturation Protection and Dynamic Output Voltages
________________________________________________________________ Maxim Integrated Products
1
24
23
22
21
20
1
2
3
4
5
7
8
9
10
11
14
15
16
17
18
24-PIN THIN QFN
4mm x 4mm
TOP VIEW
MAX1992
DL
TON
N.C.
LSAT
PGOOD
ILIM
6
REF
BST
DH
V+
13
SKIP
LX
CSP
OUT
12
CSN
FB
N.C.
N.C.
OVP/UVP
SHDN
V
CC
AGND
PGND
19
V
DD
Pin Configurations
19-2661; Rev 0; 10/02
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX1992
ETG
-40°C to +85°C
24 Thin QFN 4mm
×
4mm
MAX1993
ETG
-40°C to +85°C
24 Thin QFN 4mm
×
4mm
Pin Configurations continued at end of data sheet.
MAX1992/MAX1993
Quick-PWM Step-Down Controllers with Inductor
Saturation Protection and Dynamic Output Voltages
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
(Note 1)
ELECTRICAL CHARACTERISTICS
(V+ = 15V, V
CC
= V
DD
= SHDN = 5V, SKIP = GND,
T
A
= 0°C to +85°C
, unless otherwise noted. Typical values are at T
A
= +25°C.)
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.
V+ to AGND............................................................-0.3V to +30V
V
CC
to AGND............................................................-0.3V to +6V
V
DD
to PGND............................................................-0.3V to +6V
PGOOD, ILIM, SKIP, SHDN to AGND ......................-0.3V to +6V
REFIN, FB, CSP to AGND.........................................-0.3V to +6V
GATE, OD to GND (MAX1993 only) .........................-0.3V to +6V
TON, OVP/UVP, LSAT to AGND .................-0.3V to (V
CC
+ 0.3V)
REF, OUT to AGND ....................................-0.3V to (V
CC
+ 0.3V)
FBLANK to GND (MAX1993 only) ..............-0.3V to (V
CC
+ 0.3V)
DL to PGND................................................-0.3V to (V
DD
+ 0.3V)
CSN to AGND............................................................-2V to +30V
DH to LX .....................................................-0.3V to (BST + 0.3V)
LX to AGND ...............................................................-2V to +30V
BST to LX..................................................................-0.3V to +6V
AGND to PGND (MAX1992 only) ..........................-0.3V to +0.3V
REF Short Circuit to AGND.........................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
24-Pin 4mm x 4mm Thin QFN
(derated 20.8mW/°C above +70°C)...........................1667mW
Operating Temperature Range
MAX199_ETG ..................................................-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 MAX1993, AGND and PGND refer to a single pin designated GND.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
PWM CONTROLLER
V
IN
Battery voltage, V+
2
28
Input Voltage Range
V
BIAS
V
CC
, V
DD
4.5
5.5
V
FB = GND
2.475
2.5
2.525
Output Voltage Accuracy
(MAX1992 Fixed)
V
OUT
MAX1992
V+ = 4.5V to 28V,
SKIP = V
CC
(Note 2)
FB = V
CC
1.782
1.8
1.818
V
Feedback Voltage Accuracy
(MAX1992 Adjustable)
V
FB
MAX1992 V+ = 4.5V to 28V, SKIP = V
CC
(Note 2)
0.693
0.7
0.707
V
REFIN = 0.35
×
REF
0.693
0.7
0.707
Feedback Voltage Accuracy
(MAX1993)
V
FB
MAX1993
V+ = 4.5V to 28V,
SKIP = V
CC
(Note 2)
REFIN = REF
1.980
2
2.020
V
Load Regulation Error
I
LOAD
= 0 to 3A, SKIP = V
CC
0.1
%
Line Regulation Error
V
CC
= 4.5V to 5.5V, V+ = 4.5V to 28V
0.25
%
FB Input Bias Current
I
FB
-0.1
+0.1
µA
Output Adjust Range
0.7
5.5
V
FB = GND
90
190
350
MAX1992
FB = V
CC
or adjustable
70
145
270
OUT Input Resistance
R
OUT
MAX1993
400
800
1400
k
OUT Discharge Mode
On-Resistance
R
DISCHARGE
10
25
OUT Synchronous Rectifier
Discharge Mode Turn-On Level
0.2
0.3
0.4
V
Soft-Start Ramp Time
t
SS
Rising edge on SHDN to full current limit
1.7
ms
MAX1992/MAX1993
Quick-PWM Step-Down Controllers with Inductor
Saturation Protection and Dynamic Output Voltages
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, V
CC
= V
DD
= SHDN = 5V, SKIP = GND,
T
A
= 0°C to +85°C
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
TON = GND (600kHz)
170
194
219
TON = REF (450kHz)
213
243
273
TON = open (300kHz)
316
352
389
On-Time
t
ON
V+ = 15V,
V
OUT
= 1.5V
(Note 3)
TON = V
CC
(200kHz)
461
516
571
ns
Minimum Off-Time
t
OFF(MIN)
(Note 3)
400
500
ns
FB forced above the regulation point,
LSAT = GND
0.55
0.85
Quiescent Supply Current (V
CC
)
I
CC
FB forced above the regulation point,
V
LSAT
> 0.5V
1
mA
Quiescent Supply Current (V
DD
)
I
DD
FB forced above the regulation point
<1
5
µA
Quiescent Supply Current (V+)
I
V+
25
40
µA
Shutdown Supply Current (V
CC
)
SHDN = GND
<1
7
µA
Shutdown Supply Current (V
DD
)
SHDN = GND
<1
5
µA
Shutdown Supply Current (V+)
SHDN = GND, V+ = 28V,
V
CC
= V
DD
= 0 or 5V
<1
5
µA
REFERENCE
T
A
= +25°C to +85°C
1.986
2
2.014
Reference Voltage
V
REF
V
CC
= 4.5V to 5.5V,
I
REF
= 0
T
A
= 0°C to +85°C
1.983
2
2.017
V
Reference Load Regulation
V
REF
I
REF
= -10µA to 50µA
-0.01
+0.01
V
REF Lockout Voltage
V
REF(UVLO)
Rising edge, hysteresis = 350mV
1.95
V
REFIN Voltage Range
0.7
V
REF
V
REFIN Input Bias Current
I
REFIN
0.01
0.05
µA
FAULT DETECTION
Overvoltage Trip Threshold
With respect to error comparator threshold,
OVP/UVP = V
CC
12
16
20
%
Overvoltage Fault Propagation
Delay
t
OVP
FB forced 2% above trip threshold
10
µs
Output Undervoltage Protection
Trip Threshold
With respect to error comparator threshold,
OVP/UVP = V
CC
65
70
75
%
Output Undervoltage Protection
Blanking Time
t
BLANK
From rising edge of
SHDN
10
35
ms
Output Undervoltage Fault
Propagation Delay
t
UVP
10
µs
PGOOD Lower Trip Threshold
With respect to error comparator threshold,
hysteresis = 1%
-13
-10
-7
%
PGOOD Upper Trip Threshold
With respect to error comparator threshold,
hysteresis = 1%
+7
+10
+13
%
PGOOD Propagation Delay
t
PGOOD
FB forced 2% beyond PGOOD trip
threshold
10
µs
MAX1992/MAX1993
Quick-PWM Step-Down Controllers with Inductor
Saturation Protection and Dynamic Output Voltages
4
_______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, V
CC
= V
DD
= SHDN = 5V, SKIP = GND,
T
A
= 0°C to +85°C
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
PGOOD Output Low Voltage
I
SINK
= 4mA
0.3
V
PGOOD Leakage Current
I
PGOOD
FB = REF (PGOOD high impedance),
PGOOD forced to 5.5V
1
µA
FBLANK = V
CC
120
218
320
FBLANK = open
80
140
205
Fault Blanking Time
t
FBLANK
FBLANK = REF
35
63
95
µs
Thermal Shutdown Threshold
T
SHDN
Hysteresis = 15°C
160
°C
V
CC
Undervoltage Lockout
Threshold
V
UVLO(VCC)
Rising edge, PWM disabled below this level
hysteresis = 20mV
4.1
4.25
4.4
V
CURRENT LIMIT
ILIM Adjustment Range
0.25
2.00
V
CSP
0
2.7
Current-Limit Input Range
CSN
-0.3
+28.0
V
CSP/CSN Input Current
-0.5
+0.5
µA
Valley Current-Limit Threshold
(Fixed)
V
LIM(VAL)
V
CSP
- V
CSN
, ILIM = V
CC
45
50
55
mV
V
ILIM
= 250mV
15
25
35
Valley Current-Limit Threshold
(Adjustable)
V
LIM(VAL)
V
CSP
- V
CSN
V
ILIM
= 2.00V
170
200
230
mV
Current-Limit Threshold
(Negative)
V
NEG
V
CSP
- V
CSN
,
SKIP = ILIM = V
CC
,
T
A
= +25°C
-75
-60
-45
mV
Current-Limit Threshold
(Zero Crossing)
V
ZX
With respect to valley current-limit
threshold, V
CSP
- V
CSN
,
SKIP = GND,
ILIM = V
CC
2.5
mV
LSAT = V
CC
180
200
220
LSAT = open
157
175
193
Inductor Saturation Current-Limit
Threshold
With respect to
valley current-limit
threshold,
ILIM = V
CC
LSAT = REF
135
150
165
%
ILIM Saturation Fault Sink Current
I
ILIM(LSAT)
V
CSP
- V
CSN
> inductor saturation current
limit, 0.25V < V
ILIM
< 2.0V
4
6
8
µA
ILIM Leakage Current
V
CSP
- V
CSN
< inductor saturation current
limit
0.1
µA
GATE DRIVERS
DH Gate Driver On-Resistance
R
DH
BST - LX forced to 5V
1.5
5
DL, high state
1.5
5
DL Gate Driver On-Resistance
R
DL
DL, low state
0.6
3
DH Gate Driver Source/Sink
Current
I
DH
DH forced to 2.5V, BST - LX forced to 5V
1
A
DL Gate Driver Source Current
I
DL(SOURCE)
DL forced to 2.5V
1
A
MAX1992/MAX1993
Quick-PWM Step-Down Controllers with Inductor
Saturation Protection and Dynamic Output Voltages
_______________________________________________________________________________________
5
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, V
CC
= V
DD
= SHDN = 5V, SKIP = GND,
T
A
= 0°C to +85°C
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DL Gate Driver Sink Current
I
DL(SINK)
DL forced to 2.5V
3
A
DL rising
35
Dead Time
t
DEAD
DH rising
26
ns
INPUTS AND OUTPUTS
OD On-Resistance
R
OD
GATE = V
CC
10
25
OD Leakage Current
GATE = GND, OD forced to 5.5V
1
200
nA
Logic Input Threshold
SHDN, SKIP, GATE
rising edge, hysteresis = 225mV
1.20
1.7
2.20
V
Logic Input Current
SHDN, SKIP, GATE
-1
+1
µA
High
1.9
2.0
2.1
Dual ModeTM Threshold Voltage
MAX1992 FB
Low
0.05
0.1
0.15
V
High
V
CC
-
0.4V
Open
3.15
3.85
REF
1.65
2.35
Four-Level Input Logic Levels
TON, OVP/UVP,
LSAT, FBLANK
Low
0.5
V
Four-Level Logic Input Current
TON, OVP/UVP, LSAT,
FBLANK forced to GND or V
CC
-3
+3
µA
ELECTRICAL CHARACTERISTICS
(V+ = 15V, V
CC
= V
DD
= SHDN = 5V, SKIP = GND,
T
A
= -40°C to +85°C
, unless otherwise noted.) (Note 4)
PARAMETER
SYMBOL
CONDITIONS
MIN
MAX
UNITS
PWM CONTROLLER
V
IN
Battery voltage, V+
2
28
Input Voltage Range
V
BIAS
V
CC
, V
DD
4.5
5.5
V
FB = GND
2.462
2.538
Output Voltage Accuracy
(MAX1992 Fixed)
V
OUT
MAX1992,
V+ = 4.5V to 28V,
SKIP = V
CC
(Note 2)
FB = V
CC
1.773
1.827
V
Feedback Voltage Accuracy
(MAX1992 Adjustable)
V
FB
MAX1992, V+ = 4.5V to 28V,
SKIP = V
CC
(Note 2)
0.689
0.711
V
REFIN = 0.35
×
REF
0.689
0.711
Feedback Voltage Accuracy
(MAX1993)
V
FB
MAX1993,
V+ = 4.5V to 28V,
SKIP = V
CC
(Note 2)
REFIN = REF
1.970
2.030
V
TON = GND (600kHz)
170
219
TON = REF (450kHz)
213
273
TON = open (300kHz)
316
389
On-Time
t
ON
V+ = 15V,
V
OUT
= 1.5V
(Note 3)
TON = V
CC
(200kHz)
461
571
ns
Dual Mode is a trademark of Maxim Integrated Products, Inc.
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