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SC1402
2000 SEMTECH CORP.
652 MITCHELL ROAD
NEWBURY PARK CA 91320
Multi-Output, Low-Noise Power Supply
Controller for Notebook Computers
December 15, 2000
1
DESCRIPTION
The SC1402 is pin compatible with the MAX1632 with
improved load regulation performance. The SC1402 is
a multiple-output power supply controller designed to
power logic supply components in battery operated
systems. The SC1402 utilizes synchronous rectified
buck topologies to generate two voltages, (3.3V and
5V) with up to 95% efficiency. It also provides two lin-
ear regulators for system housekeeping functions. The
12V linear regulator output is generated from a coupled
inductor of the 5V switching regulator.
Control functions include: power up sequencing, soft
start, power-good signaling, automatic bootstrapping
for high side MOSFETs, and frequency synchroniza-
tion. An internal precision 2.5V reference ensures 2%
output voltage. The internal oscillator can be adjusted
to 200kHz, 300kHz or synchronized to an external
clock. The MOSFET drivers provide 1A peak drive
current for fast MOSFET switching.
The SC1402 includes a PSAVE enable input to select
a pulse skipping mode for high efficiency or a fixed fre-
quency mode for low noise operation.
FEATURES
=
6V to 30V Input range
=
3.3V and 5V dual synchronous rectified outputs
=
Fixed frequency or PSAVE for maximum efficiency
over wide load current range
=
5V/50mA linear regulator
=
12V/120mA linear regulator
=
Precision 2.5V reference output
=
Programmable power-up sequence
=
Power good output (RESET)
=
Output over current protection
=
Output over voltage protection
=
Output under voltage shut down
=
4A typical shut down current
=
7mW typical quiescent power
APPLICATIONS
=
Notebook and subnotebook computers
=
PDAs and Mobile communicators
=
Desktop DC-DC converters
DEVICE
PACKAGE
(1)
TEMP. (T
A
)
SC1402ISS
SSOP-28
-40 - +85C
ORDERING INFORMATION:
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
TYPICAL APPLICATION CIRCUIT
Note:
(1) Only available in tape and reel packaging. (Suffix `.TR').
SC1402
2000 SEMTECH CORP.
652 MITCHELL ROAD
NEWBURY PARK CA 91320
Multi-Output, Low-Noise Power Supply
Controller for Notebook Computers
December 15, 2000
2
ABSOLUTE MAXIMUM RATINGS
PARAMETERS
MAXIMUM
UNITS
V+, BST3, BST5 to GND
-0.3, +36
V
PGND to GND
0.3
V
PHASE3 to BST3, and PHASE5 to BST5
-6 to +0.3
V
VL to GND
-0.3 to 6
V
REF,SYNC,SEQ,PSAVE,TIME_ON5,RESET to GND
-0.3 to (VL+.3V)
V
RUN/ON3, SHDN to GND
-0.3 to (V+ + 0.3V)
V
VDD
to GND
-0.3 to +30V
V
12 Out to GND
-0.3 to (VDD + 0.3V)
V
VL, REF Short to GND
Continuous
sec.
12 Out Short to GND
Continuous
sec.
REF Current
+5
mA
VL Current
+50
mA
12 Out Current
+200
mA
VDD Shunt Current
+15
mA
T
S
Storage Temperature
-65 to +150
C
T
L
Lead soldering temperature
+300, 10 seconds
C
ELECTRICAL CHARACTERISTICS
(1)
(Unless otherwise noted: V+ = 15V, both PWMs on, SYNC = VL, VL load = 0mA, REF load = 0mA, PSAVE = 0V, T
A
=-40 to +85C.
Typical values are at T
A
= +25C).
PARAMETER
CONDITIONS
MIN
TYP
MAX UNITS
MAIN SMPS CONTROLLERS
Input Voltage Range
6.0
30.0
V
3V Output Voltage in
Adjustable Mode
V+ = 6V to 30V, CSH3-CSL3 = 0V,
CSL3 tied to FB3
2.45
2.5
2.55
V
3V Output Voltage in Fixed Mode V+ = 6V to 30V, 0mV < CSH3-CSL3 < 80mV,
FB3 = 0V
3.17
3.3
3.43
V
5V Output Voltage in Adjustable
Mode
V+ = 6V to 30V, CSH5-CSL5 = 0V,
CSL5 tied to FB5
2.45
2.5
2.55
V
5V Output Voltage in Fixed Mode V+ = 6V to 30V, 0mV < CSH5-CSL5 < 80mV,
FB5 = 0V
4.82
5.0
5.18
V
Output Voltage Adjust Range
Either SMPS
REF
5.5
V
Adjustable-Mode Threshold
Voltage
Dual Mode comparator
0.5
1.3
V
Load Regulation
Either SMPS, 0V < CSH_-CSL_ < 80mV
-0.8
%
Line Regulation
Either SMPS, 6V < V+ < 30V
0.03
%/V
Current-Limit Threshold
CSH3-CSL3 or CSH5-CSL5
PSAVE = VL or V12OUT < 11.9V
80
-50
100
-100
120
-150
mV
PSAVE Mode Threshold
PSAVE = 0V, not tested
10
25
40
mV
Soft-Start Ramp Time
From enable to 95% full current limit with
respect to f
OSC
Note 2.
512
clks
Oscillator Frequency
SYNC = VL
SYNC = 0V
270
170
300
200
330
235
kHz
Maximum Duty Factor
SYNC = VL
SYNC = 0V
94
96
%
SC1402
2000 SEMTECH CORP.
652 MITCHELL ROAD
NEWBURY PARK CA 91320
Multi-Output, Low-Noise Power Supply
Controller for Notebook Computers
December 15, 2000
3
Table 2
ELECTRICAL CHARACTERISTICS (continued)
(Unless otherwise noted: (V+ = 15V, both PWMs on, SYNC = VL, VL load = 0mA, REF load = 0mA, PSAVE = 0V, T
A
= -40 to +85C
Typical values are at T
A
= +25C).
PARAMETER
CONDITIONS
MIN
TYP MAX UNITS
SYNC Input High Pulse
2
300
SYNC Input Low Pulse Width
2
300
ns
SYNC Rise/Fall Time
2
200
SYNC Input Frequency Range
240
350
kHz
Current-Sense Input Leakage
Current
V+ = VL = 0V,
CSL3 = CSH3 = CSL5 = CSH5 = 5.5V
0.01
10
A
FLYBACK CONTROLLER
VDD Shunt Threshold
Rising edge, hysteresis = 1%
18
20
V
VDD Shunt Sink Current
VDD = 20V
5
10
30
mA
VDD Leakage Current
VDD
= 5V , Standby mode
30
A
12V LINEAR REGULATOR
12OUT Output Voltage
0mA < Load < 120mA
11.55
12.1 12.50
V
12OUT Current Limit
12OUT forced to 11V, VDD = 13V
150
mA
12OUT Regulation Threshold
Falling edge
11.9
V
Quiescent VDD Current
VDD = 18V, run mode, no 12OUT load
50
100
A
INTERNAL REGULATOR AND REFERENCE
VL
Output Voltage
SHDN = V+, 6V < V+ < 30V, 0mA < ILOAD <
50mA, RUN/ON3 = TIME/ON5 = 0V
4.6
5.2
Undervoltage Fault Lockout
Threshold
Falling edge, hysteresis = 0.9V
3.5
3.7
4.0
V
Switchover Threshold
Switch over at startup
4.5
REF Output Voltage
No external load, Standby Mode
2.45
2.5
2.55
REF Load Regulation
0A < LOAD
< 50A
12.5
mV
0mA < LOAD < 5mA
50
REF Sink Current
10
A
REF Fault Lockout Voltage
Falling edge
1.8
2.2
V
V+ Operating Supply Current
VL switched over to CSL5, 5V SMPS on
10
50
V+ Standby Supply Current
V+ = 6V to 30V, SMPS off, includes current into
SHDN
180
A
V+ Shutdown Supply Current
V+ = 6V to 30V, SHDN = 0V
4
20
Quiescent Power Consumption
SMPS enabled, FB3 = FB5 = 0V,
CSL3 = CSH 3 = 3.5V, CSL5 = CSH5 = 5.5V
7.5
mW
SC1402
2000 SEMTECH CORP.
652 MITCHELL ROAD
NEWBURY PARK CA 91320
Multi-Output, Low-Noise Power Supply
Controller for Notebook Computers
December 15, 2000
4
Note 1: This device is ESD sensitive. Use of standard ESD handling precautions is required.
Note 2: Guaranteed by design.
ELECTRICAL CHARACTERISTICS (continued)
(Unless otherwise noted: (V+ = 15V, both PWMs on, SYNC = VL, VL load = 0mA, REF load = 0mA, PSAVE = 0V, T
A
= -40 to +85C
Typical values are at T
A
= +25C).
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
FAULT DETECTION
Overvoltage Trip Threshold
With respect to unloaded output voltage
3.5
7
10
%
Overvoltage-Fault
Propagation Delay
CSL_ driven 2% above overvoltage trip threshold
1.5
s
Output Undervoltage
Threshold
With respect to unloaded output voltage
60
70
80
%
Output Undervoltage
Lockout Time
From each SMPS enabled, with respect to f
OSC
5000
6144
7000
clks
Thermal Shutdown
Threshold
Typical hysteresis = +10C
150
C
RESET
RESET Trip Threshold
With respect to unloaded output voltage, falling
edge; typical hysteresis = 1%
-10
-7
-4
%
RESET Propagation Delay
Falling edge, CSL_ driven 2% below RESET trip
threshold
1.5
s
RESET Delay Time
With respect to fOSC
27,000 32,000 37,000
clks
INPUTS AND OUTPUTS
Logic Input Low Voltage
RUN/ON3, PSAVE, TIME/ON5 (SEQ = REF),
SHDN, SYNC
0.6
V
Logic Input High Voltage
RUN/ON3, PSAVE, TIME/ON5 (SEQ = REF),
SHDN, SYNC
2.4
V
Input Leakage Current
RUN/ON3, PSAVE, TIME/ON5 (SEQ = REF),
SHDN, SYNC, SEQ = 0V or 3.3V
+
1
A
Logic Output Low Voltage
RESET, ISINK = 4mA
0.4
V
Logic Output High Current
RESET = 3.5V
1
mA
TIME/ON5 Input Trip Level
SEQ = 0 or VL
2.4
2.6
V
TIME/ON5 Source Current
TIME/ON5 = 0V, SEQ = 0 or VL
2
3
4
A
TIME/ON5 On-Resistance
TIME/ON5, RUN/ON3 = 0V, SEQ = 0 or VL
100
Gate Driver Sink/Source
Current
DL3, DH3, DL5, DH5, forced to 2V
1
A
Gate Driver On-Resistance
High or low
1.5
7
SC1402
2000 SEMTECH CORP.
652 MITCHELL ROAD
NEWBURY PARK CA 91320
Multi-Output, Low-Noise Power Supply
Controller for Notebook Computers
December 15, 2000
5
BLOCK DIAGRAM
VL
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