19-2569; Rev 0; 10/02
Dual Step-Down Controllers Plus Linear-
Regulator Controller for Notebook Computers
General Description
The MAX1816/MAX1994 are dual step-down controllers
for notebook computer applications. BUCK1 is a CPU
core regulator with dynamically adjustable output, ultra-
fast transient response, high DC accuracy, and high effi-
ciency. BUCK2 is an adjustable step-down regulator for
I/O and memory supplies. Both regulators employ Maxim’s
proprietary Quick-PWM™ control architecture. This fast-
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 main-
taining a relatively constant switching frequency. The
MAX1816/MAX1994 also have a linear-regulator controller
for low-voltage auxiliary power supplies.
The CPU regulator supports “active voltage positioning”
to reduce output bulk capacitance and lower power dis-
sipation. A programmable gain amplifier allows the use
of lower value sense resistors. Four fixed-gain settings
are available (0, 1.5, 2, and 4). A differential remote-
sense amplifier is also included to more accurately con-
trol the voltage at the load. Accuracy is further
enhanced with an internal integrator.
The MAX1816/MAX1994 include a specialized digital
interface that makes them suitable for mobile CPU and
video processor applications. The power-good
(PGOOD) output for the core regulator is forced high
during VID transitions, and the LINGOOD output for the
linear regulator includes a 1ms (min) turn-on delay.
BUCK1, BUCK2, and the linear regulator feature overvolt-
age protection (OVP). The detection threshold for BUCK1
is adjusted with an external resistive voltage-divider, while
the OVP thresholds for BUCK2 and the linear regulator
are fixed. Connecting the OVPSET pin to V
CC
disables
OVP for BUCK1 and BUCK2, but not the linear regulator.
The MAX1816 features an output-voltage adjustment
range from 0.6V to 1.75V. Similarly, the MAX1994 is
adjustable from 0.925V to 2.0V, using an alternate VID
code set. While in suspend mode, the adjustment range
is 0.7V to 1.075V for both the MAX1816 and MAX1994.
Both parts are available in 48-pin thin QFN packages.
o
Dual Quick-PWM Architecture
o
±1% V
OUT
Accuracy
o
5-Bit On-Board D/A Converter
o
+0.60V to +1.75V Output Adjust Range (MAX1816)
o
+0.70V to +2.00V Output Adjust Range (MAX1994)
o
Voltage-Positioning Gain and Offset Control
o
+2V to +28V Battery Input Range
o
Differential Remote Sense (BUCK1)
o
Linear-Regulator Controller
o
200/300/550/1000kHz Switching Frequency
o
2.2mA (typ) I
CC
Supply Current
o
20µA (max) Shutdown Supply Current
o
Independent Power-Good Outputs
(PGOOD, LINGOOD)
Features
MAX1816/MAX1994
Ordering Information
PART
MAX1816ETM
MAX1994ETM
TEMP RANGE
-40°C to +100°C
-40°C to +100°C
PIN-PACKAGE
48 Thin QFN
48 Thin QFN
Pin Configuration
BST1
LX1
BST2
38
DL2
DH2
LX2
41
40
39
TOP VIEW
DH1
PERF
DL1
PGND
V
DD
48
47
46
45
44
43
42
37
36
35
34
33
32
31
V+
ILIM1
CC
CS1+
CS1-
FBS
GDS
GAIN
OFS0
OFS1
OFS2
SUS
DPSLP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
ILIM2
CS2
OUT2
FB2
REF
V
CC
AGND
LINBSE
LINGOOD
LINFB
TIME
OVPSET
Applications
Mobile CPU Core and Video Processors
Memory I/O and VID Supplies
3- to 4-Cell Li+ Battery to CPU Core Supply
Small Notebook Computers
MAX1816
MAX1994
30
29
28
27
26
25
SKP1/SDN
SKP2/SDN
D1
D2
D3
D4
S0
S1
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
THIN QFN 7mm
×
7mm
________________________________________________________________
Maxim Integrated Products
LIN/SDN
PGOOD
TON
D0
1
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.
Dual Step-Down Controllers Plus Linear-
Regulator Controller for Notebook Computers
MAX1816/MAX1994
ABSOLUTE MAXIMUM RATINGS
V+ to AGND............................................................-0.3V to +30V
V
CC
, V
DD
to AGND...................................................-0.3V to +6V
PGND, GDS to AGND .........................................................±0.3V
SKP1/SDN, SKP2/SDN, LIN/SDN to AGND............-0.3V to +16V
LINBSE, SUS, PERF,
DPSLP,
PGOOD,
LINGOOD, CS1+, CS1-, FBS, D0–D4,
OUT2 to AGND.....................................................-0.3V to +6V
OFS0, OFS1, OFS2, ILIM1, ILIM2,
FB2, REF, TON, TIME, OVPSET, S0, S1,
GAIN, CC, LINFB to AGND ....................-0.3V to (V
CC
+ 0.3V)
DL1, DL2 to PGND .....................................-0.3V to (V
DD
+ 0.3V)
DH1 to LX1 ..............................................-0.3V to (V
BST1
+ 0.3V)
DH2 to LX2 ..............................................-0.3V to (V
BST2
+ 0.3V)
BST1 to LX1..............................................................-0.3V to +6V
BST2 to LX2..............................................................-0.3V to +6V
LX1, LX2, CS2 to AGND ............................................-2V to +30V
REF Short Circuit to AGND.........................................Continuous
LINBSE Short Circuit to +6V.......................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
48-Pin Thin QFN (derate 26.3mW/°C above +70°C) .2105mW
Operating Temperature Range .........................-40°C to +100°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°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.
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V+ = 15V, V
OUT1
= 1.20V, V
OUT2
= 2.50V, V
CC
= V
DD
= 5.0V, V
SKP1/SDN
= V
SKP2/SDN
= V
LIN/SDN
= 5.0V,
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25°C, unless otherwise noted.)
PARAMETER
Input Voltage Range
Battery voltage V+
V
CC
, V
DD
V+ = 4.5V to 28V,
includes load
regulation errors,
OFS_ = GDS = AGND,
CS1+ = CS1- = FBS
V+ = 4.5V to 28V
DAC codes from 0.600V to
1.750V (MAX1816)
-1
DAC codes from 0.700V to
2.000V (MAX1994)
FB2 = GND
FB2 = V
CC
FB2 = OUT2
Voltage level to enable internal feedback for BUCK2
with V
OUT2
= 2.5V
Voltage level to enable external feedback for BUCK2
with FB2 regulated to 1.0V nominal
Voltage level to enable internal feedback for BUCK2
with V
OUT2
= 1.8V
GAIN = GND
Voltage-Positioning Gain
GAIN = REF
GAIN = open
GAIN = V
CC
1.425
1.900
3.800
0.15
2.10
0
1.500
2.000
4.000
1.575
2.100
4.200
V/V
2.475
1.782
0.990
1.0
2.500
1.800
1.000
2.525
1.818
1.010
5.5
0.05
1.90
V
V
V
V
V
+1
%
CONDITIONS
TON = REF, open, or V
CC
TON = GND
MIN
2
2
4.5
TYP
MAX
28
16
5.5
V
UNITS
BUCK1 DC Output Voltage
Accuracy
BUCK2 Error Comparator Threshold
(DC Output Voltage Accuracy)
(Note 1)
OUT2 Adjust Range
FB2 GND Level
FB2 External Feedback Level
FB2 V
CC
Level
2
_______________________________________________________________________________________
Dual Step-Down Controllers Plus Linear-
Regulator Controller for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V+ = 15V, V
OUT1
= 1.20V, V
OUT2
= 2.50V, V
CC
= V
DD
= 5.0V, V
SKP1/SDN
= V
SKP2/SDN
= V
LIN/SDN
= 5.0V,
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25°C, unless otherwise noted.)
PARAMETER
Current-Sense Differential Input
Range (CS1+, CS1-)
Remote-Sense Differential Input
Range (CS1+, FBS)
Remote-Sense Differential Input
Range (GDS, AGND)
CS1+, FBS Input Bias Current
CS1- Input Bias Current
GDS Input Bias Current
FB2 Input Bias Current
OUT2 Input Resistance
252kHz nominal, R
TIME
= 143kΩ
TIME Frequency Accuracy
53kHz nominal to 530kHz nominal,
R
TIME
= 680kΩ to 68kΩ
V+ = 5V, CS1- = 1.2V
BUCK1 On-Time (Note 2)
V+ = 12V, CS1- = 1.2V
V+ = 5V, OUT2 = 2.5V
BUCK2 On-Time (Note 2)
V+ = 12V, OUT2 = 2.5V
TON = GND (1000kHz)
TON = REF (550kHz)
TON = open (300kHz)
TON = V
CC
(200kHz)
TON = GND (715kHz)
TON = REF (390kHz)
TON = open (390kHz)
TON = V
CC
(260kHz)
Minimum Off-Time
Quiescent Supply Current (V
CC
)
Partial Shutdown Supply Current
(Linear Regulator On Only)
TON = open, TON = V
CC
(Note 2)
TON = GND, TON = REF (Note 2)
Measured at V
CC
, with FBS, OUT2, FB2, and LINFB
forced above the no-load regulation point
V
SKP1/SDN
= 0V, V
SKP2/SDN
= 0V, V
LIN/SDN
= 5V;
measured at V
CC
, with FBS and LINFB forced above
the no-load regulation point
V
SKP1/SDN
= 5V, V
SKP2/SDN
= 0V, V
LIN/SDN
= 5V;
measured at V
CC
, with FBS and LINFB forced above
the no-load regulation point
V
SKP1/SDN
= 0V, V
SKP2/SDN
= 5V, V
LIN/SDN
= 0V;
measured at V
CC
, with OUT2 and FB2 forced above
the regulation point
Measured at V
DD
, with FBS, OUT2, and FB2 forced
above the no-load regulation point
-300mV < V
CS1+
- V
FBS
< +300mV
-100mV < V
CS1+
- V
CS1-
< +100mV, V
CS1-
= V
FBS
-60
-60
-3
-0.2
70
-8
-12
230
165
320
465
630
495
495
740
260
190
355
515
720
550
550
825
425
325
2200
+8
+12
290
215
390
565
810
605
605
910
500
375
3800
ns
µA
ns
ns
%
CONDITIONS
MIN
TYP
MAX
200
300
200
+60
+60
+3
+0.2
UNITS
mV
mV
mV
µA
µA
µA
µA
kΩ
MAX1816/MAX1994
425
650
µA
Partial Shutdown Supply Current
(BUCK1 and Linear Regulator)
1825
3000
µA
Partial Shutdown Supply Current
(BUCK2 Only)
Quiescent Supply Current (V
DD
)
600
1100
µA
<1
5
µA
_______________________________________________________________________________________
3
Dual Step-Down Controllers Plus Linear-
Regulator Controller for Notebook Computers
MAX1816/MAX1994
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V+ = 15V, V
OUT1
= 1.20V, V
OUT2
= 2.50V, V
CC
= V
DD
= 5.0V, V
SKP1/SDN
= V
SKP2/SDN
= V
LIN/SDN
= 5.0V,
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25°C, unless otherwise noted.)
PARAMETER
Quiescent Battery Current
Shutdown Supply Current (V
CC
)
Shutdown Supply Current (V
DD
)
Shutdown Battery Current
Reference Voltage
Reference Load Regulation
Reference Sink Current
OVPSET Disable Mode Threshold
OVPSET Default Mode Threshold
for BUCK1
Overvoltage Trip Threshold for
BUCK1 (Fixed OVP Threshold)
Measured at V+
V
SKP1/SDN
= 0V, V
SKP2/SDN
= 0V, and V
LIN/SDN
= 0V
V
SKP1/SDN
= 0V, V
SKP2/SDN
= 0V, and V
LIN/SDN
= 0V
V
SKP1/SDN
= V
SKP2/SDN
= 0V, measured at V+, with
V
CC
= V
DD
= 0V or 5V
V
CC
= 4.5V to 5.5V, I
REF
= 50µA sourcing
I
REF
= 0 to 50µA
I
REF
= 50µA to 100µA
REF in regulation
Voltage at OVPSET above which the OVP functions
are disabled for BUCK1 and BUCK2
Voltage at OVPSET below which the OVP thresholds
are set to their default values
OVPSET = GND,
measured at FBS
V
OVPSET
= 1.0V,
measured at FBS
V
OVPSET
= 2.0V,
measured at FBS
MAX1816
MAX1994
MAX1816
MAX1994
MAX1816
MAX1994
1.98
0
0
10
V
CC
-
1.5
0.4
1.95
2.20
0.95
1.075
1.95
2.20
113
-100
10
65
70
10
256
4096
75
2.00
2.25
1.00
1.125
2.00
2.25
115
V
CC
-
0.5
0.6
2.05
2.30
1.05
1.175
2.05
2.30
117
+100
%
nA
µs
%
µs
Clks
Clks
V
CONDITIONS
MIN
TYP
25
4
<1
<1
2.00
MAX
40
10
5
5
2.02
7
7
UNITS
µA
µA
µA
µA
V
mV
µA
V
V
V
Overvoltage Trip Threshold for
BUCK1 (Adjustable Threshold)
Overvoltage Trip Threshold for
BUCK2
OVPSET Bias Current
Overvoltage Fault Propagation
Delay
Output Undervoltage Protection
Threshold
Output Undervoltage Fault
Propagation Delay
Output Undervoltage Protection
Blanking Time for FBS
Output Undervoltage Protection
Blanking Time for OUT2
Linear Regulator (LINFB)
Undervoltage Protection Blanking
Time
Measured at OUT2 (or FB2 if external feedback is
used)
0V < V
OVPSET
< V
CC
FBS, OUT2, FB2, and LINFB forced 2% above the
no-load trip threshold
With respect to unloaded output voltage, FBS, and
OUT2 (FB2 in external feedback)
FBS, OUT2, FB2, and LINFB forced 2% below trip
threshold
From SKP1/SDN signal going high; clock speed set
by R
TIME
(Note 3)
From SKP2/SHDN signal going high; clock speed set
by R
TIME
(Note 3)
Linear regulator; from LIN/SDN signal going high;
clock speed set by R
TIME
(Note 3)
512
Clks
4
_______________________________________________________________________________________
Dual Step-Down Controllers Plus Linear-
Regulator Controller for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V+ = 15V, V
OUT1
= 1.20V, V
OUT2
= 2.50V, V
CC
= V
DD
= 5.0V, V
SKP1/SDN
= V
SKP2/SDN
= V
LIN/SDN
= 5.0V,
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25°C, unless otherwise noted.)
PARAMETER
ILIM1 Default Threshold
BUCK1 Current-Limit Threshold
(Fixed)
CS1+ - CS1-; V
ILIM1
= V
CC
CS1+ - CS1-; V
ILIM1
= 0.5V
CS1+ - CS1-; V
ILIM1
= 2.0V
BUCK1 Negative Current-Limit
Threshold (Fixed)
ILIM1 Input Bias Current
CS2 Input Bias Current
ILIM2 Default Threshold
BUCK2 Current-Limit Threshold
(Fixed)
AGND - CS2; V
ILIM2
= V
CC
AGND - CS2; V
ILIM2
= 0.5V
AGND - CS2; V
ILIM2
= 2.0V
BUCK2 Negative Current-Limit
Threshold (Fixed)
ILIM2 Input Bias Current
Thermal-Shutdown Threshold
V
CC
Undervoltage Lockout
Threshold
DH1 Gate-Driver On-Resistance
DL1 Gate-Driver On-Resistance
DH1 Gate-Driver Source/Sink
Current
DL1 Gate-Driver Sink Current
DL1 Gate-Driver Source Current
Dead Time
DH2 Gate-Driver On-Resistance
DL2 Gate-Driver On-Resistance
AGND - CS2; V
ILIM2
= V
CC
0 to 2V
15°C hysteresis
Rising edge, hysteresis = 20mV
BST1–LX1 forced to 5V (Note 4)
DL1 high state (pullup) (Note 4)
DL1 low state (pulldown) (Note 4)
DH1 forced to 2.5V, BST–LX forced to 5V
DL1 forced to 2.5V
DL1 forced to 2.5V
DL1 rising
DH1 rising
BST2–LX2 forced to 5V (Note 4)
DL2 high state (pullup) (Note 4)
DL2 low state (pulldown) (Note 4)
4.10
1
1
0.35
1.5
5
1.5
35
26
2
2
0.7
8
8
3
CS1+ - CS1-; V
ILIM1
= V
CC
0 to 2V
0 to 28V
CONDITIONS
MIN
V
CC
-
1.5
40
40
160
-90
-100
-1
V
CC
-
1.5
40
40
160
-90
-100
160
4.45
4.5
4.5
2
V
CC
-
1.0
50
50
200
-72
TYP
V
CC
-
1.0
50
50
200
-72
MAX
V
CC
-
0.5
60
60
mV
240
-55
+100
+1
V
CC
-
0.5
60
60
mV
240
-55
+100
mV
nA
o
MAX1816/MAX1994
UNITS
V
mV
BUCK1 Current-Limit Threshold
(Adjustable)
mV
nA
µA
V
mV
BUCK2 Current-Limit Threshold
(Adjustable)
C
V
Ω
Ω
A
A
A
ns
Ω
Ω
_______________________________________________________________________________________
5
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