MAX8741 Datasheet, PDF (10/33 Pages) Maxim Integrated Products – 500kHz Multi-Output Power-Supply Controllers with High Impedance in Shutdown

500kHz Multi-Output Power-Supply Controllers
with High Impedance in Shutdown
PIN
SSOP
TQFN
15
13
16
14
17
15
18
17
19
18
20
19
21
20
22
21
23
22
24
23
25
24
26
26
27
27
28
28
—
6, 16, 25, 32
NAME
SEQ
DH5
LX5
BST5
DL5
PGND
V_L
V+
SHDN
DL3
BST3
LX3
DH3
RUN/ON3
N.C.
Pin Description (continued)
FUNCTION
Pin-Strap Input that Selects the SMPS Power-Up Sequence:
SEQ = GND: 5V before 3.3V, RESET output determined by both outputs
SEQ = REF: Separate ON3/ON5 controls, RESET output determined by 3.3V
output
SEQ = V_L: 3.3V before 5V, RESET output determined by both outputs
Gate-Drive Output for the 5V, High-Side N-Channel Switch. DH5 is a floating driver
output that swings from LX5 to BST5, riding on the LX5 switching-node voltage.
Switching-Node (Inductor) Connection. Can swing 2V below ground without hazard.
Boost Capacitor Connection for High-Side Gate Drive (0.1µF)
Gate-Drive Output for the Low-Side Synchronous-Rectifier MOSFET. Swings 0 to V_L.
Power Ground
5V Internal Linear-Regulator Output. V_L is also the supply-voltage rail for the chip.
After the 5V SMPS output has reached 4.5V (typ), V_L automatically switches to the
output voltage through CSL5 for bootstrapping. Bypass to GND with 4.7µF. V_L
supplies up to 25mA for external loads.
Battery Voltage Input, 4.2V to 30V. Bypass V+ to PGND close to the IC with a 0.22µF
capacitor. Connects to a linear regulator that powers V_L.
Shutdown Control Input, Active Low. Logic threshold is set at approximately 1V. For
automatic startup, connect SHDN to V+ through a 220kΩ resistor and bypass SHDN to
GND with a 0.01µF capacitor.
Gate-Drive Output for the Low-Side Synchronous-Rectifier MOSFET. Swings 0 to VL.
Boost Capacitor Connection for High-Side Gate Drive (0.1µF)
Switching-Node (Inductor) Connection. Can swing 2V below ground without hazard.
Gate-Drive Output for the 3.3V, High-Side N-Channel Switch. DH3 is a floating driver
output that swings from LX3 to BST3, riding on the LX3 switching-node voltage.
ON/OFF Control Input. See the Power-Up Sequencing and ON/OFF Controls section.
No Connection
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