|
Features
1.3V to 3.5V 5-bit programmable output voltage
Synchronous rectification
Power Good flag and output enable
Over-voltage protection
Initial Output Accuracy: 1.5% over temperature
Current limit without external sense resistor
Adaptive non-overlapping MOSFET gate drives
Adjustable switching frequency: 50 kHz to 1 MHz
Dynamic output voltage positioning
1.256V reference voltage available externally
Plastic SO-20 package and TSSOP-20 package
Description The LM2636 is a high speed controller designed specifically for use in synchronous DC/DC buck converters for advance d microprocessors.
A 5-bit DAC accepts the VID code directly from the CPU and adjusts the output voltage from 1.3V to 3.5V. It provides the power
good, over-voltage protection, and output enable features as required by Intel VRM specifications. Current limiting is achieved
by monitoring the voltage drop across the rDS_ON of the high side MOSFET, which eliminates an expensive current sense resistor.
The LM2636 employs a fixed-frequency voltage mode PWM architecture. To provide a faster response to a large and fast load
transient, two ultra-fast comparators are built in to monitor the output voltage and override the primary control loop when
necessary. The PWM frequency is adjustable from 50 kHz to 1 MHz through an external resistor. The wide range of PWM frequency
gives the power supply designer the flexibility to make trade-offs between load transient response performance, MOSFET cost
and the overall efficiency. The adaptive non-overlapping MOSFET gate drivers help avoid any potential shoot-through problem
while maintaining high efficiency. BiCMOS gate drivers with rail-to-rail swing ensure that no spurious turn-on occur. When
only 5V is available, a bootstrap structure can be employed to accommodate an NMOS high side switch. The precision reference
trimmed to 2.5% over temperature is available externally for use by other regulators. Dynamic positioning of load voltage,
which helps cut the number of output capacitors, can also be implemented easily.
Applications
Motherboard power supply/VRM for Cyrix Gxm, Cyrix Gxi, Cyrix MII, Pentium II, Pentium Pro, 6x86 and K6 processors
5V to 1.3V–3.5V high current power supplies
|
Also Recommended
| LM2727▲ | Single Channel, Vout Down To 0.6V |
| LM2633▲ | Dual Controller, One Sub-Bangap Output Channel |
|
|
