(PDF) MAX796 Datasheet PDF | Maxim





MAX796 Datasheet PDF

Part Number MAX796
Description Step-Down Controllers with Synchronous Rectifier for CPU Power
Manufacture Maxim
Total Page 30 Pages
PDF Download Download MAX796 Datasheet PDF

Features: Datasheet pdf 19-0221; Rev 3a; 11/97 UALS IT MAN TION K A ET U E L H A S A EV W DAT FOLLO S tep-Down Controllers with Synchronous R ectifier for CPU Power ________________ ____________Features o 96% Efficiency o 4.5V to 30V Input Range o 2.5V to 6V A djustable Output o o o o o o o o o Pres et 3.3V and 5V Outputs (at up to 10A) M ultiple Regulated Outputs +5V Linear-Re gulator Output Precision 2.505V Referen ce Output Automatic Bootstrap Circuit 1 50kHz/300kHz Fixed-Frequency PWM Operat ion Programmable Soft-Start 375µA Typ Quiescent Current (VIN = 12V, VOUT = 5V ) 1µA Typ Shutdown Current __________ _____General Description The MAX796/MAX 797/MAX799 high-performance, stepdown D C-DC converters with single or dual out puts provide main CPU power in battery- powered systems. These buck controllers achieve 96% efficiency by using synchr onous rectification and Maxim’s propr ietary Idle Mode™ control scheme to e xtend battery life at full-load (up to 10A) and no-load outputs. Excellent dynamic response corrects output .

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MAX796 datasheet
19-0221; Rev 3a; 11/97
EVAFLOULALTOIWONDKAITTAMSAHNEUEATLS
Step-Down Controllers with
Synchronous Rectifier for CPU Power
_______________General Description
The MAX796/MAX797/MAX799 high-performance, step-
down DC-DC converters with single or dual outputs
provide main CPU power in battery-powered systems.
These buck controllers achieve 96% efficiency by using
synchronous rectification and Maxim’s proprietary Idle
Mode™ control scheme to extend battery life at full-load
(up to 10A) and no-load outputs. Excellent dynamic
response corrects output transients caused by the latest
dynamic-clock CPUs within five 300kHz clock cycles.
Unique bootstrap circuitry drives inexpensive N-channel
MOSFETs, reducing system cost and eliminating the
crowbar switching currents found in some PMOS/NMOS
switch designs.
The MAX796/MAX799 are specially equipped with a sec-
ondary feedback input (SECFB) for transformer-based
dual-output applications. This secondary feedback path
improves cross-regulation of positive (MAX796) or nega-
tive (MAX799) auxiliary outputs.
The MAX797 has a logic-controlled and synchronizable
fixed-frequency pulse-width-modulating (PWM) operating
mode, which reduces noise and RF interference in sensi-
tive mobile-communications and pen-entry applications.
The SKIP override input allows automatic switchover to
idle-mode operation (for high-efficiency pulse skipping) at
light loads, or forces fixed-frequency mode for lowest noise
at all loads.
The MAX796/MAX797/MAX799 are all available in 16-
pin DIP and narrow SO packages. See the table below
to compare these three converters.
PART
MAX796
MAX797
MAX799
MAIN OUTPUT
SPECIAL FEATURE
3.3V/5V or adj.
Regulates positive secondary
voltage (such as +12V)
3.3V/5V or adj. Logic-controlled low-noise mode
3.3V/5V or adj.
Regulates negative secondary
voltage (such as -5V)
________________________Applications
Notebook and Subnotebook Computers
PDAs and Mobile Communicators
Cellular Phones
____________________________Features
o 96% Efficiency
o 4.5V to 30V Input Range
o 2.5V to 6V Adjustable Output
o Preset 3.3V and 5V Outputs (at up to 10A)
o Multiple Regulated Outputs
o +5V Linear-Regulator Output
o Precision 2.505V Reference Output
o Automatic Bootstrap Circuit
o 150kHz/300kHz Fixed-Frequency PWM Operation
o Programmable Soft-Start
o 375µA Typ Quiescent Current (VIN = 12V, VOUT = 5V)
o 1µA Typ Shutdown Current
______________Ordering Information
PART
MAX796CPE
MAX796CSE
MAX796C/D
MAX796EPE
MAX796ESE
MAX796MJE
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
PIN-PACKAGE
16 Plastic DIP
16 Narrow SO
Dice*
16 Plastic DIP
16 Narrow SO
16 CERDIP
Ordering Information continued at end of data sheet.
*Contact factory for dice specifications.
__________________Pin Configuration
TOP VIEW
SS 1
(SECFB) SKIP 2
REF 3
GND 4
SYNC 5
SHDN 6
FB 7
CSH 8
MAX796
MAX797
MAX799
16 DH
15 LX
14 BST
13 DL
12 PGND
11 VL
10 V+
9 CSL
Idle Mode is a trademark of Maxim Integrated Products.
U.S. and foreign patents pending.
( ) ARE FOR MAX796/MAX799.
DIP/SO
________________________________________________________________ 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 408-737-7600 ext. 3468.

MAX796 datasheet
Step-Down Controllers with
Synchronous Rectifier for CPU Power
ABSOLUTE MAXIMUM RATINGS
V+ to GND .................................................................-0.3V, +36V
GND to PGND........................................................................±2V
VL to GND ...................................................................-0.3V, +7V
BST to GND ...............................................................-0.3V, +36V
DH to LX...........................................................-0.3V, BST + 0.3V
LX to BST.....................................................................-7V, +0.3V
SHDN to GND............................................................-0.3V, +36V
SYNC, SS, REF, FB, SECFB, SKIP, DL to GND..-0.3V, VL + 0.3V
CSH, CSL to GND .......................................................-0.3V, +7V
VL Short Circuit to GND..............................................Momentary
REF Short Circuit to GND ...........................................Continuous
VL Output Current ...............................................................50mA
Continuous Power Dissipation (TA = +70°C)
SO (derate 8.70mW/°C above +70°C) ........................696mW
Plastic DIP (derate 10.53mW/°C above +70°C) .........842mW
CERDIP (derate 10.00mW/°C above +70°C) ..............800mW
Operating Temperature Ranges
MAX79_C_ _ ......................................................0°C to +70°C
MAX79_E_ _....................................................-40°C to +85°C
MAX79_MJE .................................................-55°C to +125°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+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
(V+ = 15V, GND = PGND = 0V, IVL = IREF = 0A, TA = 0°C to +70°C for MAX79_C, TA = 0°C to +85°C for MAX79_E,
TA = -55°C to +125°C for MAX79_M, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
+3.3V AND +5V STEP-DOWN CONTROLLERS
Input Supply Range
MAX79_C
MAX79_E/M
4.5 30
V
5.0 30
5V Output Voltage (CSL)
0mV < (CSH-CSL) < 80mV, FB = VL, 6V < V+ < 30V,
includes line and load regulation
4.85 5.10 5.25
V
3.3V Output Voltage (CSL)
0mV < (CSH-CSL) < 80mV, FB = 0V, 4.5V < V+ < 30V,
includes line and load regulation
3.20 3.35 3.46
V
Nominal Adjustable Output
Voltage Range
External resistor divider
Feedback Voltage
(CSH-CSL) = 0V
Load Regulation
0mV < (CSH-CSL) < 80mV
25mV < (CSH-CSL) < 80mV
Line Regulation
6V < V+ < 30V
Current-Limit Voltage
CSH-CSL, positive
CSH-CSL, negative
SS Source Current
SS Fault Sink Current
FLYBACK/PWM CONTROLLER
SECFB Regulation Setpoint
Falling edge, hysteresis = 15mV (MAX796)
Falling edge, hysteresis = 20mV (MAX799)
INTERNAL REGULATOR AND REFERENCE
VL Output Voltage
VL Fault Lockout Voltage
SHDN = 2V, 0mA < IVL < 25mA, 5.5V < V+ < 30V
Rising edge, hysteresis = 15mV
VL/CSL Switchover Voltage
Rising edge, hysteresis = 25mV
REF
2.43
80
-50
2.5
2.0
2.505
2.5
1.5
0.04
100
-100
4.0
6
2.57
0.06
120
-160
6.5
V
V
%
%/V
mV
µA
mA
2.45
-0.05
2.505
0
2.55
0.05
V
4.7 5.3 V
3.8 4.1 V
4.2 4.7 V
2 _______________________________________________________________________________________




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