Datasheet
SLUS507D − JANUARY 2002 − REVISED NOVEMBER 2005
8
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APPLICATION INFORMATION
The TPS4000x series of synchronous buck controller devices is optimized for high-efficiency dc-to-dc
conversion in non-isolated distributed power systems. A typical application circuit is shown in Figure 1.
The TPS40004 and TPS40005 are the controllers of choice for most general purpose synchronous buck
designs. Each operates in two quadrant mode (i.e. source or sink current) full time. This choice provides the
best performance for output voltage load transient response over the widest load current range.
The TPS40001 and TPS40003 add an additional feature: They operate in single quadrant mode (i.e. source
current only) during converter startup, and then when the converter has reached the regulation point, the
controllers change to operate in two quadrant mode. This is useful for applications that have outputs pre-biased
at some voltage before the controller is enabled. When the TPS40001 or TPS40003 is enabled, it does not sink
current during startup and therefore does not pull current from the pre-biased voltage supply.
The TPS40000 and TPS40002 operate in single quadrant mode (source current only) full time, allowing the
paralleling of converters. Single quadrant operation ensures one converter does pull current from a paralleled
converter. A converter using one of these controllers emulates a non-synchronous buck converter at light loads.
When current in the output inductor attempts to reverse, an internal zero-current detection circuit turns OFF the
synchronous rectifier and causes the current flow in the inductor to become discontinuous. At average load
currents greater than the peak amplitude of the inductor ripple current, the converter returns to operation as a
synchronous buck converter to maximize efficiency.
UDG−02013
10 µF
20 kW
100 µF
7.68 kΩ
470 µF
10 µF
15.7 kΩ
243 Ω
10 kΩ
V
OUT
1.8 V
10 A
1.0 µH
Si4836DY
IHLP5050CE−01
Si4836DY
5
8
7
10
9
1
2
3
ILIM
FB
COMP
GND
HDRV
SW
VDD
LDRV
3.6 nF
4
4.7 nF
SS/SD
6
BOOT
100 pF
TPS40001
100 nF
3.3 nF
3.3 Ω
V
DD
3.0 V to 5.5 V
Figure 1. Typical Application Circuit