Linear Technology LTC3773EG Quick Start Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 908A
DESCRIPTION
Demonstration circuit 908A is a Polyphase 3-
Output Step-Down Supply with Tracking featuring
the LTC3773EG. The output voltages are 3.3V,
2.5V and 1.8V and the maximum load current for
each is 15A. The input voltage range is 7V to 24V.
Typical applications include
tions, computers and industrial power supplies.
The board can be programmed for either continu-
ous-conduction mode (CCM), pulse skip mode
(DCM) or Burst Mode (BM). Other features of the
Table 1. Performance Summary (T
PARAMETER
Minimum Input Voltage
Maximum Input Voltage
V
OUT1
V
OUT2
V
OUT3
Typical output voltage ripple for VOUT1
Typical output voltage ripple for VOUT2
Typical output voltage ripple for VOUT3
Nominal Switching Frequency
Efficiency
(see Figure 4 for typical efficiency curves)
POLYPHASE 3-OUTPUT STEP-DOWN SUPPLY WITH TRACKING
servers, communica-
= 25°C)
A
CONDITION
V = 7V to 24V, I
IN
V = 7V to 24V, I
IN
V = 7V to 24V, I
IN
VIN = 12V, IOUT1 = 15A, 20MHz BW
VIN = 12V, IOUT2 = 15A, 20MHz BW
VIN = 12V, IOUT3 = 15A, 20MHz BW
V = 12V, V
IN OUT1
V = 12V, V
IN OUT2
V = 12V, V
IN OUT3
board include an SDB pin which can be used for
rail sequencing, a phase mode pin, and a dynamic
load circuit for each rail.
An on-board LT1933 (5V / 500mA buck converter)
provides current for the LTC3773EG's internal
logic and gate drive circuitry. The 5V bias can also
be supplied externally. If an external bias voltage
is applied it needs to be between 4.5V and 7.0V.
Design files for this circuit board are available. Call
the LTC factory.
= 0A to 15A
OUT
= 0A to 15A
OUT
= 0A to 15A
OUT
= 3.3V, I = 15A
OUT1
= 2.5V, I = 15A
OUT2
= 1.8V, I = 15A
OUT3
LTC3773EG
VALUE
7V
24V
3.3V ±3%
2.5V ±3%
1.8V ±3%
25mVp-p TYP
25mVp-p TYP
25mVp-p TYP
220kHz TYP
92.2% TYP
90.9% TYP
88.9% TYP
1