MAX1960/MAX1961/MAX1962
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM
Step-Down Controllers with Voltage Margining
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Pin Description
PIN
MAX1960 MAX1961 MAX1962
NAME FUNCTION
1 1 1 CLKOUT
Clock Output. Connect to FSET/SYNC of a second converter to operate 180° out-of-
phase. CLKOUT swings from V
CC
to GND. CLKOUT is low in shutdown (see the
Operating Frequency and Synchronization section).
2 2 2 FSET/SYNC
Frequency Set and Synchronization. Connect to GND for 500kHz operation,
connect to V
CC
for 1MHz operation, or drive with clock signal to synchronize
(between 450kHz and 1200kHz).
3 3 — ILIM
Current Limit. Connect a resistor from ILIM to GND to set the current-sense
threshold voltage. Connect ILIM to V
DD
to select the default threshold of 75mV.
—— 3 ENE nab l e. D r i ve hi g h for nor m al op er ati on. D r i ve l ow or connect to GN D for shutd ow n m od e.
— 4 4 SEL
Preset Output Voltage Select. Allows the output to be set to one of four preset
voltages (1.5V, 1.8V, 2.5V, and 3.3V). For the MAX1962, FB must be connected to
V
DD
if SEL is to be used (see the Setting the Output Voltage section).
4 — — N.C. No Connection. Not internally connected.
— 8 5 OUT
Output. Connect to the output. Used to sense the output voltage for internal
feedback and current sense.
5 5 — CTL1
6 6 — CTL2
Control Pins. Controls voltage margining and shutdown. Connect both CTL1 and
CTL2 high for normal operation. Connect both CTL1 and CTL2 low for shutdown.
Connect CTL1 high and CTL2 low for +4% voltage margining. Connect CTL1 low
and CTL2 high for -4% voltage margining. If voltage margining is not to be used,
connect CTL1 and CTL2 together and use to enable/shutdown the device.
—— 6 CS
C ur r ent- S ense Inp ut. C onnect to the j uncti on of the cur r ent- sense r esi stor and the
i nd uctor . The M AX 1962 cur r ent- sense thr eshol d i s 50m V m easur ed fr om C S to O U T.
777AV
DD
Filtered Supply from V
DD
. Connect a 1µF bypass capacitor. AV
DD
is forced to V
CC
in shutdown. Do not apply an external load to AV
DD
.
8—8 FB
Feed b ack Inp ut. The feed b ack thr eshol d i s 0.8V . C onnect to the center of a r esi sti ve
vol tag e- d i vi d er fr om the outp ut to GN D to set the outp ut vol tag e to 0.8V or g r eater . On
the M AX 1962, connect FB to V
DD
to sel ect p r eset outp ut vol tag es ( see S E L) .
9 9 9 COMP Compensation Pin. COMP is forced to GND in shutdown, UVLO, or thermal fault.
10 10 10 REF Reference Output. V
REF
= 1.28V. Bypass with a 0.22µF capacitor to GND.
11 11 11 GND
Analog Ground. Connect to the PC board analog ground plane. Connect the PC
board analog ground plane and power ground planes with a single connection.
12 12 12 V
DD
C har g e- P um p O utp ut. P r ovi d es r eg ul ated 5V to p ow er the IC and g ate d r i ver s.
Byp ass w i th a 4.7µF cer am i c cap aci tor for op er ati ng fr eq uenci es b etw een 450kH z
and 950kH z. Byp ass w i th a 2.2µF cer am i c cap aci tor for 1M H z op er ati on. V
DD
i s
i nter nal l y for ced to V
CC
i n shutd ow n. D o not ap p l y an exter nal l oad to V
DD
.
13 13 13 DL
Low-Side MOSFET Synchronous Rectifier Gate-Driver Output. DL is high in
shutdown.
14 14 14 PGND Power Ground. Connect to the PC board power ground plane.
