Datasheet
MAX767
5V-to-3.3V, Synchronous, Step-Down
Power-Supply Controller
_______________________________________________________________________________________ 5
______________________________________________________________Pin Description
16
NAME FUNCTION
1
CS Current-sense input: +100mV = nominal current-limit level referred to FB.
2 SS Soft-start input. Ramp time to full current limit is 1ms/nF of capacitance to GND.
3 ON
ON/O
—
F
—
F
–
control input to disable the PWM. Tie directly to V
CC
for automatic start-up.
PIN
DL Gate-drive output for the low-side synchronous rectifier MOSFET
4–7, 11 GND Low-current analog ground. Feedback reference point for the output.
8 REF 3.3V internal reference output. Bypass to GND with 0.22µF minimum capacitor.
9 SYNC
Oscillator control/synchronization input. Connect to V
CC
or GND for 200kHz; connect to REF for
300kHz. For external clock synchronization in the 240kHz to 350kHz range, a high-to-low transition
causes a new cycle to start.
10, 14, 15 V
CC
Supply voltage input: 4.5V to 5.5V
17 BST Boost capacitor connection (0.1µF)
12 N.C. No internal connection
13 PGND Power ground
18 LX Inductor connection. Can swing 2V below GND without latchup.
19 DH Gate-drive output for the high-side MOSFET
20 FB Feedback and current-sense input for the PWM
OUTPUT
3.3V
LX
DL
GND
SS
MAX767
ON
V
CC
REF
L1
BST
DH
D2
PGND
CS
FB
SHUTDOWN
ON/OFF
N1
N2
D1
SMALL-
SIGNAL
SCHOTTKY
C1
R1
C3
0.1
µ
F
C2
C6
0.22µF
C5
(OPTIONAL)
SYNC
R2
10
Ω
INPUT
4.5V TO 5.5V
0.01
µ
F
C4
4.7
µ
F
Figure 1. Standard Application Circuit