SC2422A Datasheet, PDF (1/10 Pages) Semtech Corporation – BIPHASE CURRENT MODE CONTROLLER

BIPHASE CURRENT MODE
CONTROLLER
SC2422A
PRELIMINARY - August 7, 2000
DESCRIPTION
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FEATURES
The SC2422A biphase, current mode controller is de-
signed to work with Semtech smart synchronous
drivers, such as the SC1205, SC1305 or the SC1405 to
provide the DC/DC converter solution for the most
demanding Micro-processor applications. Input current
rather than output current sensing is used to guarantee
precision phase to phase current matching using a
single sense resistor on the input power line. Accurate
current sharing and pulse by pulse current limit are
implemented without the power loss and transient re-
sponse degradation associated with output current
sense methods. Two phase operation allows significant
reduction in input/output ripple while enhancing tran-
sient response.
The DAC step size and range are programmable with
external components thus allowing compliance with
new and emerging VID ranges.
A novel approach implements active droop, minimizing
output capacitor requirements during load transients.
This avoids the pitfalls of the passive droop implemen-
tation. This feature also allows easy implementation of
N+1 redundancy and current sharing among modules.
Programmable Under Voltage Lockout assures proper
start-up and shutdown by synchronizing the controller
to the driver supply. Wide PWM frequency range allows
use of low profile, surface mount components.
TYPICAL APPLICATION SCHEMATIC
• Precision, pulse by pulse phase current match-
ing
• Active drooping allows for best transient response
• Input Sensing Current mode control
• Programmable DAC step size/offset allows
Compliance with VRM9.0, VRM8.3 or VRM8.4
• Externally programmable soft-start
• 5V or 12V input for next generation processors
• 0% minimum duty cycle improves transient re-
sponse
• Externally Programmable UVLO with hysteresis
• Cycle by cycle current limiting
• Programmable Internal Oscillator to 1 MHz
• VID IIIII Inhibit (No CPU)
APPLICATIONS
• Intel Advanced Microprocessors
• AMD Athlon^TM power supplies
• Servers/Workstations, high density power supplies
ORDERING INFORMATION
DEVICE⁽¹⁾
SC2422ACS.TR
PACKAGE
SO-16
TEMP. RANGE (T_J)
0 - 125°C
SC2422A.EVB
Evaluation Board
Note:
(1) Only available in tape and reel packaging. A reel con-
tains 1000 devices.
INPUT
Rsens
VIN
Rf
Ri
1 _VID4
2 _VID3
3 _VID2
4
VID1
5 _VID0
6 _ERROUT
7
FB
8 _RREF
VCC ¹⁶
BGOUT ¹⁵
OC+ ¹⁴
13
OUT1
OUT2 ¹²
OC- ¹¹
10
UVLO
GND ⁹
Rref
SC2422A
© 2000 SEMTECH CORP.
1 _IN
3
VCC
4
VDD
DRVH ⁷
6
PHASE
5
DRVL
SC1305
1 _IN
3
VCC
4
VDD
DRVH ⁷
6
PHASE
5
DRVL
VIN
SC1305
Vout
1
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