General Description
The MAX8792 pulse-width modulation (PWM) controller provides high efficiency, excellent transient response,and high D C-output accuracy needed for stepping down high-voltage batteries to generate low-voltage core or chipset/RAM bias supplies in notebook comput-ers. The output voltage can be dynamically controlled using the dynamic REFIN, which supports input volt-ages between 0 to 2V. The REFIN adjustability com-bined with a resistive voltage-divider on the feedback input allows the MAX8792 to be configured for any out-put voltage between 0 to 0.9V IN .
Maxim’s proprietary Quick-PWM? quick-response, con-stant-on-time PWM control scheme handles wide input/output voltage ratios (low-duty-cycle applications)with ease and provides 100ns “instant-on” response to load transients while maintaining a relatively constant switching frequency. Strong drivers allow the MAX8792to efficiently drive large synchronous-rectifier MOSFETs.The controller senses the current across the synchro-nous rectifier to achieve a low-cost and highly efficient valley current-limit protection. The adjustable current-limit threshold provides a high degree of flexibility,allowing thermally compensated protection using an NTC or foldback current-limit protection using a volt-age-divider derived from the output.
The MAX8792 includes a voltage-controlled soft-start and soft-shutdown in order to limit the input surge cur-rent, provide a monotonic power-up (even into a precharged output), and provide a predictable power-up time. The controller also includes output fault protec-tion—undervoltage and overvoltage protection—as well as thermal-fault protection.
The MAX8792 is available in a tiny 14-pin, 3mm x 3mm TD FN package. For space-constrained applications,refer to the MAX17016 single step-down with 10A, 26V internal MOSFETs available in a small 40-pin, 6mm x 6mm TQFN package.
.
Applications Notebook Computers
I/O and Chipset Supplies GPU Core Supply
DDR Memory—VDDQ or VTT Point-of-Load Applications Step-Down Power Supply
Features
o Quick-PWM with Fast Transient Response o Supports Any Output Capacitor
No Compensation Required with
Polymers/Tantalum
Stable with Ceramic Output Capacitors Using
External Compensation
o Precision 2V ±10mV Reference
o Dynamically Adjustable Output Voltage (0 to 0.9V IN Range)
Feedback Input Regulates to 0 to 2V REFIN
Voltage
0.5% V OUT Accuracy Over Line and Load o 26V Maximum Input Voltage Rating
o Adjustable Valley Current-Limit Protection
Thermal Compensation with NTC Supports Foldback Current Limit
o Resistively Programmable Switching Frequency o Overvoltage Protection
o Undervoltage/Thermal Protection
o Voltage Soft-Start and Soft-Shutdown
o Monotonic Power-Up with Precharged Output o Power-Good Window Comparator
MAX8792
Single Quick-PWM Step-Down Controller with Dynamic REFIN
________________________________________________________________Maxim Integrated Products
1
Pin Configuration
Ordering Information
For pricing, delivery, and ordering information,please contact Maxim Direct at 1-888-629-4642,or visit Maxim’s website at https://www.doczj.com/doc/0d9408444.html,.
temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
M A X 8792
Single Quick-PWM Step-Down Controller with Dynamic REFIN
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
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.
TON to GND...........................................................-0.3V to +28V V DD to GND..............................................................-0.3V to +6V V CC to GND................................................-0.3V to (V DD + 0.3V)EN, SKIP , PGOOD to GND.......................................-0.3V to +6V REF, REFIN to GND....................................-0.3V to (V CC + 0.3V)ILIM, FB to GND.........................................-0.3V to (V CC + 0.3V)DL to GND..................................................-0.3V to (V DD + 0.3V)BST to GND.................................................(V DD - 0.3V) to +34V BST to LX..................................................................-0.3V to +6V BST to V DD .............................................................-0.3V to +28V
DH to LX....................................................-0.3V to (V BST + 0.3V)REF Short Circuit to GND...........................................Continuous Continuous Power Dissipation (T A = +70°C)14-Pin 3mm x 3mm TDFN
(derated 24.4mW/°C above +70°C)....................1951mW
Operating Temperature Range (extended).........-40°C to +85°C Junction Temperature......................................................+150°C Storage Temperature.........................................-65°C to +150°C Lead Temperature (soldering, 10s).................................+300°C Soldering Temperature (reflow).......................................+240°C
MAX8792
Single Quick-PWM Step-Down Controller with Dynamic REFIN
_______________________________________________________________________________________3
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V = 12V, V = V = V = 5V, REFIN = ILIM = REF, SKIP = GND. T = 0°C to +85°C , unless otherwise spec-
M A X 8792
Single Quick-PWM Step-Down Controller with Dynamic REFIN 4_______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V IN = 12V, V DD = V CC = V EN = 5V, REFIN = ILIM = REF, SKIP = GND. T A = 0°C to +85°C , unless otherwise spec-ified. Typical values are at T A = +25°C.) (Note 1)
ELECTRICAL CHARACTERISTICS
MAX8792
Single Quick-PWM Step-Down Controller with Dynamic REFIN
_______________________________________________________________________________________5
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V IN = 12V, V DD = V CC = V EN = 5V, REFIN = ILIM = REF, SKIP = GND. T A = -40°C to +85°C , unless otherwise specified.) (Note 1)
M A X 8792
Single Quick-PWM Step-Down Controller with Dynamic REFIN 6_______________________________________________________________________________________
Note 2:The 0 to 0.5V range is guaranteed by design, not production tested.
Note 3:On-time and off-time specifications are measured from 50% point to 50% point at the DH pin with LX = GND, V BST = 5V,
and a 250pF capacitor connected from DH to LX. Actual in-circuit times can differ due to MOSFET switching speeds.
ELECTRICAL CHARACTERISTICS (continued)
1.5V OUTPUT EFFICIENCY vs. LOAD CURRENT
LOAD CURRENT (A)
E F
F I C I E N C Y (%)
1
0.1
30405060708090100200.01
10
1.5V OUTPUT EFFICIENCY vs. LOAD CURRENT
LOAD CURRENT (A)
E F F I C I E N C Y (%)
1
0.1
3040
5060708090100200.01
10
1.5V OUTPUT VOLTAGE vs. LOAD CURRENT
LOAD CURRENT (A)
O U T P U T V O L T A G E (V )
4
6
8
2
1.50
1.52
1.54
1.48
10
Typical Operating Characteristics
(MAX8792 Circuit of Figure 1, V IN = 12V, V DD = 5V, SKIP = GND, R TON = 200k Ω, T A = +25°C, unless otherwise noted.)
MAX8792
Single Quick-PWM Step-Down Controller with Dynamic REFIN
_______________________________________________________________________________________7
1.05V OUTPUT EFFICIENCY
vs. LOAD CURRENT
LOAD CURRENT (A)
E F F I C I E N C Y (%)
1
0.1
30405060708090100200.01
10
1.05V OUTPUT EFFICIENCY
vs. LOAD CURRENT
LOAD CURRENT (A)E F F I C I E N C Y (%)
10.13040506070809010020
0.0110
1.05V OUTPUT VOLTAGE vs. LOAD CURRENT
LOAD CURRENT (A)
O U T P U T V O L T A G E (V )
46821.05
1.04
1.06
1.07
1.03
010
SWITCHING FREQUENCY vs. LOAD CURRENT
LOAD CURRENT (A)
S W I T C H I N G F R E Q U E N C Y (k H z )
1
0.1
5010015020025030035000.01
10
PWM MODE SWITCHING FREQUENCY
vs. INPUT VOLTAGE
INPUT VOLTAGE (V)S W I T C H I N G F R E Q U E N C Y (k H z )
14
18
10
250270260280290300310320330
240
6
22
SWITCHING FREQUENCY
vs. TEMPERATURE
TEMPERATURE (°C)
S W I T C H I N G F R E Q U E N C Y (k H z )
20406080-20
0280
290
300
270
-40
100
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
M A X 8792 t o c 10
INPUT VOLTAGE (V)M A X I M U M O U T P U T C U R R E N T (A )
15
18
21
9
12
13.113.013.413.313.213.613.512.9
6
24MAXIMUM OUTPUT CURRENT
vs. TEMPERATURE
TEMPERATURE (°C)M A X I M U M O U T P U T C U R R E N T (A )
20406080100
-20013121117
1614
1520191810
-40NO-LOAD SUPPLY CURRENT I BIAS
vs. INPUT VOLTAGE
INPUT VOLTAGE (V)
I B I A S (m A )
12
15
18
21
9
642108121416
6
24
Typical Operating Characteristics (continued)
(MAX8792 Circuit of Figure 1, V IN = 12V, V DD = 5V, SKIP = GND, R TON = 200k Ω, T A = +25°C, unless otherwise noted.)
M A X 8792
Single Quick-PWM Step-Down Controller with Dynamic REFIN 8_______________________________________________________________________________________
NO-LOAD SUPPLY CURRENT I IN
vs. INPUT VOLTAGE
INPUT VOLTAGE (V)
I I N (m A )
12
15
18
21
9
0.1
1
101000.01
6
24
REF OUTPUT VOLTAGE vs. LOAD CURRENT
M A X 8792 t o c 14
LOAD CURRENT (μA)
O U T P U T V O L T A G E (V )
30507090100102040608001.99
2.00
2.01
2.021.98
-10110
REFIN-TO-FB OFFSET VOLTAGE DISTRIBUTION
M A X 8792 t o c 15
OFFSET VOLTAGE (mV)
S A M P L E P E R C E N T A G E (%)
10
30
20
4050
+85°C
+25°C
SAMPLE SIZE = 100
-2.5
-2.0
-1.5
-1.0
-0.5
0.5
1.0
1.5
2.0
2.520V ILIM THRESHOLD VOLTAGE DISTRIBUTION
M A X 8792
t o c 16
ILIM THRESHOLD VOLTAGE (mV)
S A M P L E P E R C E N T A G E (%
)
20
10
40
30
50
18.0
18.4
18.8
19.2
19
.6
20.0
20.4
20.8
21.2
21.6
22.0
+85°
C
+25°C
SAMPLE SIZE = 100
SOFT-START WAVEFORM
(HEAVY LOAD)
MAX8792 toc17
200μs/div
C. V OUT , 1V/div
B. INDUCTOR CURRENT, 10A/div
1.5V
8A 05V 000
5V
A B
C
D
A. EN, 5V/div
B. PGOOD, 5V/div SOFT-START WAVEFORM
(LIGHT LOAD)
MAX8792 toc18
200μs/div
C. V OUT , 1V/div
B. INDUCTOR CURRENT, 10A/div
1.5V
05V 000
5V A B C D A. EN, 5V/div B. PGOOD, 5V/div
SHUTDOWN WAVEFORM
MAX8792 toc19
200μs/div
D. V OUT , 1V/div
E. INDUCTOR CURRENT, 5A/div
1.5V 05V 5V 0000
5V A B
C
D E
A. EN, 5V/div
B. PGOOD, 5V/div
C. DL, 5V/div LOAD-TRANSIENT RESPONSE
(PWM MODE)
MAX8792 toc20
20μs/div
C. INDUCTOR CURRENT, 10A/div
1.45V
8A 1A
1.55V
8A
1A
A
B
C
A. I OUT = 1A TO 8A, 10A/div
B. V OUT , 50mV/div LOAD-TRANSIENT RESPONSE
(SKIP MODE)
MAX8792 toc21
20μs/div
C. INDUCTOR CURRENT, 10A/div 1.45V 8A 1A
1.55V
10A 0A
A B C
A. I OUT = 1A TO 8A, 10A/div
B. V OUT , 50mV/div Typical Operating Characteristics (continued)
(MAX8792 Circuit of Figure 1, V IN = 12V, V DD = 5V, SKIP = GND, R TON = 200k Ω, T A = +25°C, unless otherwise noted.)
MAX8792
Single Quick-PWM Step-Down Controller with Dynamic REFIN
_______________________________________________________________________________________
9
OUTPUT OVERLOAD WAVEFORM
(UVP ENABLED)
MAX8792 toc22
200μs/div
C. DL, 5V/div
D. PGOOD, 5V/div
5V 5V 14A 001.5V
00
A
B
C D A. INDUCTOR CURRENT, 10A/div B. V OUT , 1V/div
OUTPUT OVERVOLTAGE WAVEFORM
MAX8792 toc23
100μs/div
C. PGOOD, 5V/div
5V 5V 001.5V
A
B
C A. V OUT , 1V/div B. DL, 5V/div
DYNAMIC OUTPUT-VOLTAGE TRANSITION
(PWM MODE)
MAX8792 toc24
20μs/div
C. INDUCTOR CURRENT,
10A/div D. LX, 10V/div
-10A 01.5V 1.5V
1.05V 1.05V
12V 0
A
B
C
D
A. REFIN, 500mV/div
B. V OUT , 200mV/div
DYNAMIC OUTPUT-VOLTAGE TRANSITION
(SKIP MODE)
MAX8792 toc25
100μs/div
C. INDUCTOR CURRENT, 10A/div
D. LX, 10V/div
10A
1.5V 1.5V
1.05V 1.05V 12V 0
A
B
C
D
A. REFIN, 500mV/div
B. V OUT , 200mV/div Typical Operating Characteristics (continued)
(MAX8792 Circuit of Figure 1, V IN = 12V, V DD = 5V, SKIP = GND, R TON = 200k Ω, T A = +25°C, unless otherwise noted.)
M A X 8792
Single Quick-PWM Step-Down Controller with Dynamic REFIN 10______________________________________________________________________________________
分销商库存信息:
MAXIM
MAX8792ETD+T MAX8792EVKIT+