ML4900 Datasheet, PDF (1/8 Pages) Micro Linear Corporation – High Current Synchronous Buck Controller

July 2000
ML4900*
High Current Synchronous Buck Controller
GENERAL DESCRIPTION
FEATURES
The ML4900 high current synchronous buck controller has
been designed to provide high efficiency DC/DC
conversion for next generation processors such as the
Pentium^® Pro from Intel^®.
s Designed to meet Pentium^® Pro power supply
requirements
s DC regulation to +1% maximum
The ML4900 controller, when combined with two
N-channel MOSFETs, generates output voltages between
2.1V and 3.5V from a 5V supply. The output voltage is
selected via an internal 4-bit DAC. Output currents in
excess of 14A can be attained at efficiencies greater than
90%.
The ML4900 can be enabled/disabled via the SHDN pin.
While disabled, the output of the regulator is completely
isolated from the circuit’s input supply. The ML4900
employs fixed-frequency PWM control combined with a
dual mode control loop to provide excellent load transient
response.
s Proprietary circuitry provides transient response of +5%
maximum over 300mA to 14A load range
s Programmable output voltage (2.1V to 3.5V) is set by
an onboard 4-bit DAC
s Synchronous N-channel buck topology for maximum
power conversion efficiency
s Fixed frequency operation for easier system integration
s Integrated antishoot-through logic, short circuit
protection, and UV lockout
s Shutdown control provides load isolation
(* Indicates Part is End of Life as of July 1, 2000)
BLOCK DIAGRAM (Pin Configuration Shown for 16-Pin SOIC Version)
VDD
15
+
10.5V ^–
PROTECT
16
+
4.4V ^–
UVLO
35µA
+
4V ^–
SHDN
5
D0
1
D1
2
D2
3
D3
4
4 BIT DAC
VDAC
VDAC + 3%
+
–
VFB
+
VDAC - 3%
–
CONTROL
LOGIC
+
–
200kHz
VDAC + 10%
+
VDAC + 3%
–
VFB
+
VDAC - 10%
–
VDAC - 3%
N DRV H
14
N DRV L
13
PWR GND
12
COMP
11
VFB
9
VDAC
-73mV _ISENSE
10
PWR GOOD
6
3.5V
REFERENCE
VREF
7
GND
8
1