TS3404
Single Synchronous Buck PWM Controller
Pin assignment
1. Boot
8. Phase
2. Ugate
7. COMP
3. Gnd
6. FB
4. Lgate
5. Vcc
Oscillator Frequency up to 300KHz
0.8V Internal Reference
Drives N-Channel MOSFETs
General Description
The TS3405 makes simple work out of implementing a complete control and protection scheme for a DC-DC step-down
converter. Designed to drive N-channel MOSFETs in a synchronous buck topology, the TS3405 integrates the control,
output a adjustment, monitoring and protection functions.
The TS3405 provides simple, single feedback loop, voltage mode control with fast transient response. The output voltage
can be precisely regulated to as low as 0.8V, with a maximum tolerance of 鹵1.5% over temperature and line voltage
variations. A fixed frequency oscillator reduces design complexity, while balancing typical application cost and efficiency.
The error amplifier features a 15MHz gain-bandwidth product and 8V/uS slew rate, which enables high converter
bandwidth for fast transient performance. The resulting PWM duty cycles range from 0% to 100%. The protection from
over current conditions is provided by monitoring the Rds(on) of the lower MOSFET to inhibit PWM operation
appropriately. This approach simplifies the implementation and improves efficiency by eliminating the need for a current
sense resistor.
Features
Buck converter Vin operate from 3.3V ~ 14V
Vcc operate from 3.75V ~ 6V
Buck converter Vin can be greater than Vcc
0.8V to Vin output voltage
鹵1.5% over line voltage and temperature
Simple single 鈥搇oop control design
Voltage-mode PWM control
Loss less, programmable over current protection
uses lower MOSFET鈥檚 Rds(on)
Internal soft start
Converter can source and sink current
Fixed oscillator frequency 300KHz
Applications
Power supplies for microprocessors
Subsystem power supplies
Cable modems, set-top box, DSL modems
DSP and core communications processor supplies
Memory supplies
Personal computer peripherals
Industrial power supplies
Low-voltage distributed power supplies
Ordering Information
Part No.
TS3405CS
Operating Temp.
-40 ~ +85
o
C
Package
SOP-8
Absolute Maximum Rating
Supply Voltage
Operating Supply Voltage
Absolute Boot Voltage
Upper Driver Supply Voltage
Input, Output or I/O Voltage
Operating Junction Temperature Range
Ambient Temperature Range
Storage Temperature Range
Lead Temperature 1.6mm(1/16鈥? from case for 10Sec.
T
J
T
J
T
STG
T
LEAD
V
CC
V
CC
V
BOOT
V
BOOT
V
PHASE
6
4.5 ~ 5.5
20
20
Gnd-0.3V to Vcc+0.3V
-40 ~ +125
-40 ~ +85
-65 ~ +150
260
V
V
V
V
V
o
o
o
o
C
C
C
C
TS3405
1-10
2003/12 rev. A
1
2
3
4
5
6
7
8
9
10
