19-2661; Rev 1; 9/05
Quick-PWM Step-Down Controllers with Inductor
Saturation Protection and Dynamic Output Voltages
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-PWM™ 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.
♦
♦
♦
♦
♦
Features
Inductor Saturation Protection
Accurate Current Limit
Ultra-High Efficiency
Quick-PWM with 100ns Load-Step Response
MAX1992
1.8V/2.5V Fixed or 0.7V to 5.5V Adjustable
Output Range
MAX1993
External Reference Input
Dynamically Selectable Output Voltage
(0.7V to 5.5V)
Optional Power-Good and Fault Blanking
During Transitions
±1% V
OUT
Accuracy Over Line and Load
2V to 28V Battery Input Range (V
IN
)
200/300/450/600kHz Switching Frequency
Overvoltage/Undervoltage Protection Option
1.7ms Digital Soft-Start
Drives Large Synchronous Rectifier FETs
2V ±0.7% Reference Output
Power-Good Window Comparator
MAX1992/MAX1993
♦
♦
♦
♦
♦
♦
♦
♦
♦
Ordering Information
PART
MAX1992ETG
MAX1992ETG+
MAX1993ETG
MAX1993ETG+
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
24 Thin QFN 4mm
×
4mm
24 Thin QFN 4mm
×
4mm
24 Thin QFN 4mm
×
4mm
24 Thin QFN 4mm
×
4mm
+
Denotes lead-free package.
Pin Configurations
18
17
16
15
14
13
12
11
10
CSN
CSP
OUT
FB
N.C.
N.C
SKIP
9
8
7
1
TON
2
N.C.
3
LSAT
4
PGOOD
5
ILIM
6
REF
BST
TOP VIEW
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)
VDD
PGND
AGND
VCC
SHDN
OVP/UVP
19
20
21
22
23
24
DH
DL
LX
MAX1992
THIN QFN
4mm x 4mm
A "+" SIGN WILL REPLACE THE FIRST PIN INDICATOR ON LEAD-FREE PACKAGES.
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
Pin Configurations continued at end of data sheet.
1
________________________________________________________________
Maxim Integrated Products
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.
V+
Quick-PWM Step-Down Controllers with Inductor
Saturation Protection and Dynamic Output Voltages
MAX1992/MAX1993
ABSOLUTE MAXIMUM RATINGS
(Note 1)
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.
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
(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
PWM CONTROLLER
Input Voltage Range
V
IN
V
BIAS
Battery voltage, V+
V
CC
, V
DD
MAX1992
V+ = 4.5V to 28V,
SKIP
= V
CC
(Note 2)
FB = GND
FB = V
CC
2
4.5
2.475
1.782
0.693
0.693
1.980
2.5
1.8
0.7
0.7
2
0.1
0.25
-0.1
0.7
R
OUT
MAX1992
MAX1993
OUT Discharge Mode
On-Resistance
OUT Synchronous Rectifier
Discharge Mode Turn-On Level
Soft-Start Ramp Time
t
SS
Rising edge on
SHDN
to full current limit
R
DISCHARGE
0.2
FB = GND
FB = V
CC
or adjustable
90
70
400
190
145
800
10
0.3
1.7
+0.1
5.5
350
270
1400
25
0.4
Ω
V
ms
kΩ
28
5.5
2.525
V
1.818
0.707
0.707
V
REFIN = REF
2.020
%
%
µA
V
V
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Output Voltage Accuracy
(MAX1992 Fixed)
V
OUT
Feedback Voltage Accuracy
(MAX1992 Adjustable)
V
FB
MAX1992 V+ = 4.5V to 28V,
SKIP
= V
CC
(Note 2)
MAX1993
V+ = 4.5V to 28V,
SKIP
= V
CC
(Note 2)
REFIN = 0.35
×
REF
Feedback Voltage Accuracy
(MAX1993)
Load Regulation Error
Line Regulation Error
FB Input Bias Current
Output Adjust Range
OUT Input Resistance
V
FB
I
LOAD
= 0 to 3A,
SKIP
= V
CC
V
CC
= 4.5V to 5.5V, V+ = 4.5V to 28V
I
FB
2
_______________________________________________________________________________________
Quick-PWM Step-Down Controllers with Inductor
Saturation Protection and Dynamic Output Voltages
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
V+ = 15V,
V
OUT
= 1.5V
(Note 3)
(Note 3)
FB forced above the regulation point,
LSAT = GND
Quiescent Supply Current (V
CC
)
I
CC
FB forced above the regulation point,
V
LSAT
> 0.5V
FB forced above the regulation point
SHDN
= GND
SHDN
= GND
SHDN
= GND, V+ = 28V,
V
CC
= V
DD
= 0 or 5V
V
CC
= 4.5V to 5.5V,
I
REF
= 0
I
REF
= -10µA to 50µA
T
A
= +25°C to +85°C
T
A
= 0°C to +85°C
1.986
1.983
-0.01
1.95
0.7
I
REFIN
With respect to error comparator threshold,
OVP/UVP = V
CC
t
OVP
FB forced 2% above trip threshold
With respect to error comparator threshold,
OVP/UVP = V
CC
t
BLANK
t
UVP
With respect to error comparator threshold,
hysteresis = 1%
With respect to error comparator threshold,
hysteresis = 1%
t
PGOOD
FB forced 2% beyond PGOOD trip
threshold
-13
+7
From rising edge of
SHDN
65
10
10
-10
+10
10
-7
+13
0.01
V
REF
0.05
<1
25
<1
<1
<1
CONDITIONS
TON = GND (600kHz)
On-Time
t
ON
TON = REF (450kHz)
TON = open (300kHz)
TON = V
CC
(200kHz)
Minimum Off-Time
t
OFF(MIN)
MIN
170
213
316
461
TYP
194
243
352
516
400
0.55
MAX
219
273
389
571
500
0.85
mA
1
5
40
7
5
5
µA
µA
µA
µA
µA
ns
ns
UNITS
MAX1992/MAX1993
Quiescent Supply Current (V
DD
)
Quiescent Supply Current (V+)
Shutdown Supply Current (V
CC
)
Shutdown Supply Current (V
DD
)
Shutdown Supply Current (V+)
REFERENCE
Reference Voltage
Reference Load Regulation
REF Lockout Voltage
REFIN Voltage Range
REFIN Input Bias Current
FAULT DETECTION
Overvoltage Trip Threshold
Overvoltage Fault Propagation
Delay
Output Undervoltage Protection
Trip Threshold
Output Undervoltage Protection
Blanking Time
Output Undervoltage Fault
Propagation Delay
PGOOD Lower Trip Threshold
PGOOD Upper Trip Threshold
PGOOD Propagation Delay
I
DD
I
V+
V
REF
ΔV
REF
2
2
2.014
2.017
+0.01
V
V
V
V
µA
V
REF(UVLO)
Rising edge, hysteresis = 350mV
12
16
10
70
20
%
µs
75
35
%
ms
µs
%
%
µs
_______________________________________________________________________________________
3
Quick-PWM Step-Down Controllers with Inductor
Saturation Protection and Dynamic Output Voltages
MAX1992/MAX1993
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
PGOOD Output Low Voltage
PGOOD Leakage Current
I
PGOOD
SYMBOL
I
SINK
= 4mA
FB = REF (PGOOD high impedance),
PGOOD forced to 5.5V
FBLANK = V
CC
Fault Blanking Time
Thermal Shutdown Threshold
V
CC
Undervoltage Lockout
Threshold
CURRENT LIMIT
ILIM Adjustment Range
Current-Limit Input Range
CSP/CSN Input Current
Valley Current-Limit Threshold
(Fixed)
Valley Current-Limit Threshold
(Adjustable)
Current-Limit Threshold
(Negative)
Current-Limit Threshold
(Zero Crossing)
V
LIM(VAL)
V
LIM(VAL)
V
NEG
V
CSP
- V
CSN
, ILIM = V
CC
V
CSP
- V
CSN
V
ILIM
= 250mV
V
ILIM
= 2.00V
CSP
CSN
0.25
0
-0.3
-0.5
45
15
170
-75
50
25
200
-60
2.00
2.7
+28.0
+0.5
55
35
230
-45
V
V
µA
mV
mV
mV
t
FBLANK
T
SHDN
V
UVLO(VCC)
FBLANK = open
FBLANK = REF
Hysteresis = 15°C
Rising edge, PWM disabled below this level
hysteresis = 20mV
4.1
120
80
35
218
140
63
160
4.25
4.4
CONDITIONS
MIN
TYP
MAX
0.3
1
320
205
95
°C
V
µs
UNITS
V
µA
V
CSP
- V
CSN
,
SKIP
= ILIM = V
CC
,
T
A
= +25°C
With respect to valley current-limit
threshold, V
CSP
- V
CSN
,
SKIP
= GND,
ILIM = V
CC
With respect to
valley current-limit
threshold,
ILIM = V
CC
LSAT = V
CC
LSAT = open
LSAT = REF
V
ZX
2.5
mV
180
157
135
4
200
175
150
6
220
193
165
8
0.1
µA
µA
%
Inductor Saturation Current-Limit
Threshold
ILIM Saturation Fault Sink Current
ILIM Leakage Current
GATE DRIVERS
DH Gate Driver On-Resistance
DL Gate Driver On-Resistance
DH Gate Driver Source/Sink
Current
DL Gate Driver Source Current
I
ILIM(LSAT)
V
CSP
- V
CSN
> inductor saturation current
limit, 0.25V < V
ILIM
< 2.0V
V
CSP
- V
CSN
< inductor saturation current
limit
R
DH
R
DL
I
DH
BST - LX forced to 5V
DL, high state
DL, low state
DH forced to 2.5V, BST - LX forced to 5V
1.5
1.5
0.6
1
1
5
5
3
Ω
Ω
A
A
I
DL(SOURCE)
DL forced to 2.5V
4
_______________________________________________________________________________________
Quick-PWM Step-Down Controllers with Inductor
Saturation Protection and Dynamic Output Voltages
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
DL Gate Driver Sink Current
Dead Time
INPUTS AND OUTPUTS
OD On-Resistance
OD Leakage Current
Logic Input Threshold
Logic Input Current
Dual Mode™ Threshold Voltage
R
OD
GATE = V
CC
GATE = GND, OD forced to 5.5V
SHDN, SKIP,
GATE
rising edge, hysteresis = 225mV
SHDN, SKIP,
GATE
MAX1992 FB
High
Low
High
Four-Level Input Logic Levels
TON, OVP/UVP,
LSAT, FBLANK
Open
REF
Low
Four-Level Logic Input Current
TON, OVP/UVP, LSAT,
FBLANK forced to GND or V
CC
-3
1.20
-1
1.9
0.05
V
CC
-
0.4V
3.15
1.65
3.85
2.35
0.5
+3
µA
V
2.0
0.1
10
1
1.7
25
200
2.20
+1
2.1
0.15
Ω
nA
V
µA
V
SYMBOL
I
DL(SINK)
t
DEAD
DL rising
DH rising
CONDITIONS
DL forced to 2.5V
MIN
TYP
3
35
26
MAX
UNITS
A
ns
MAX1992/MAX1993
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
PWM CONTROLLER
Input Voltage Range
V
IN
V
BIAS
Battery voltage, V+
V
CC
, V
DD
MAX1992,
V+ = 4.5V to 28V,
SKIP
= V
CC
(Note 2)
FB = GND
FB = V
CC
2
4.5
2.462
1.773
0.689
0.689
1.970
170
213
316
461
28
5.5
2.538
V
1.827
0.711
0.711
V
REFIN = REF
TON = GND (600kHz)
On-Time
t
ON
V+ = 15V,
V
OUT
= 1.5V
(Note 3)
TON = REF (450kHz)
TON = open (300kHz)
TON = V
CC
(200kHz)
2.030
219
273
389
571
ns
V
V
SYMBOL
CONDITIONS
MIN
MAX
UNITS
Output Voltage Accuracy
(MAX1992 Fixed)
V
OUT
Feedback Voltage Accuracy
(MAX1992 Adjustable)
V
FB
MAX1992, V+ = 4.5V to 28V,
SKIP
= V
CC
(Note 2)
MAX1993,
V+ = 4.5V to 28V,
SKIP
= V
CC
(Note 2)
REFIN = 0.35
×
REF
Feedback Voltage Accuracy
(MAX1993)
V
FB
Dual Mode is a trademark of Maxim Integrated Products, Inc.
_______________________________________________________________________________________
5
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