SP6121CN-L Datasheet, PDF (1/42 Pages) Sipex Corporation – Low Voltage, Synchronous Step Down PWM Controller

®
SP6121
Low Voltage, Synchronous Step Down PWM Controller
Ideal for 2A to 10A, Small Footprint, DC-DC Power Converters
FEATURES
■ Optimized for Single Input Voltage - 3V to 5.5V
VCC 1
8 PDRV
■ High Efficiency: Greater than 95% possible
GND 2
SP6121
7 NDRV
■ Accurate, 500kHz Fixed Frequency Operation
■ Fast Transient Response
VFB 3
8 Pin nSOIC
6 ISET
■ 500µA, I_Q (25µA in Shutdown)
■ Internal, 0.4 V/ms, Soft Start Circuit
COMP 4
5 ISENSE
■ Precision 1% Reference
Now Available in Lead Free Packaging
■ Resistor Programmable Output Voltage
■ Lossless Adjustable Current Limit with
APPLICATIONS
■ High Side R_DS(ON) Sensing
■ 0% to 100% Duty Cycle Range
■ High Side PMOS Switch Negates Need for
■ Supply Bias for
- DSP
- Microprocessor Core
- I/O & Logic
■ External Charge Pump
■ Output Over Voltage Protection
■ Hiccup Mode Current Limit Protection
■ Video Cards
■ Board Level Supply in
Distributed Power Systems
DESCRIPTION
The SP6121 is a fixed frequency, voltage mode, synchronous PWM controller designed to work
from a single 5V or 3.3V input supply, providing excellent AC and DC regulation for high efficiency
power conversion. The operating frequency is internally set at 500kHz, permitting the use of
small, surface mount inductors and capacitors. Requiring only few external components, the
SP6121 packaged in an 8-pin SOIC, is especially suited for low voltage applications where cost,
small size and high efficiency are critical. With its low voltage capability and inherent 100% duty
cycle operation, the SP6121 allows low dropout operation in the event of a low input supply
voltage condition.
TYPICAL APPLICATION CIRCUIT
RV_CC
5
CB
3.3µF
®
V_CC
PDRV
SP6121
GND _U1 NDRV
V_FB
I_SET
RSET
2.3k
Q1
Q2
DS
3.3V
C_IN
V_IN
47µF
Ceramic 6.3V
1.8µH
L1
C_OUT
470µF x 2
1.9V 8A
V_OUT
R1
5.2k
COMP
I_SENSE
RZ
R2
10k
10k
CP
50pF
CZ
3.7nF
Q1 = FAIRCHILD FDS6375
Q2 = FAIRCHILD FDS6690A
DS = STMICROELECTRONICS STPS2L25BU
L1 = PANASONIC ETQ-P6F1R6SFA
C_OUT = SANYO 4TPB470M
Date: 11/29/04
SP6121 Low Voltage, Synchronous Step Down PWM Controller
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© Copyright 2004 Sipex Corporation