EN5337QI
Functional Block Diagram
PVIN
EN5337QI
UVLO
Thermal Limit
Current Limit
Over Voltage
NC(SW)
VOUT
P-Drive
N-Drive
(-)
PWM
Comp
(+)
PGND
Compensation
Network
PLL / Sawtooth
Generator
SYNC
(-)
XFB
EAOUT
Error
Amp
(+)
power
Good
Logic
ENABLE
SS
POK
AVIN
Soft Start
Voltage
Regulated
Voltage
Reference
EAOUT
AGND
Figure 4: Functional Block Diagram
Functional Description
Synchronous Buck Converter
Protection Features:
The
EN5337QI
is
a
synchronous,
The power supply has the following protection
features:
• Over-current protection (to protect the IC
from excessive load current)
• Thermal shutdown with hysteresis.
• Under-voltage lockout circuit to disable the
converter output when the input voltage is
less than approximately 2.2V
programmable power supply with integrated
power MOSFET switches and integrated
inductor. The nominal input voltage range is
2.375V to 5.5V. The output voltage is
programmed using an external resistor divider
network. The control loop is voltage-mode with
a type III compensation network. Much of the
compensation circuitry is internal to the device.
However, a phase lead capacitor is required
along with the output voltage feedback resistor
divider to complete the type III compensation
network. The device uses a low-noise PWM
topology. Up to 3A of continuous output current
can be drawn from this converter. The 5MHz
switching frequency allows the use of small
size input / output capacitors, and realizes a
wide loop bandwidth within a small foot print.
Additional Features:
• The switching frequency can be phase-
locked to an external clock to eliminate or
move beat frequency tones out of band.
• Soft-start circuit, limiting the in-rush current
when the converter is initially powered up.
The soft start time is programmable with
appropriate choice of soft start capacitor
value.
©Enpirion 2009 all rights reserved, E&OE
7
www.enpirion.com
02638
6/18/2009
Rev:D
ENPIRION [ ENPIRION, INC. ]
