MAX8566 Maxim Integrated Products, MAX8566 Datasheet - Page 14

• Manufacturer Part Number: MAX8566
• Description: PWM Internal-Switch Step-Down Regulator
• Manufacturer: Maxim Integrated Products

The UVLO circuitry inhibits switching when V
below 2V. Once V
the soft-start function activates. A 100mV hysteresis is
built in for glitch immunity.
When starting up into a precharged output, the MAX8566
does not discharge the output prior to entering soft-start
(known as monotonic startup). Drive MODE to 1/3 of V
to enable monotonic startup mode. Connect MODE to
GND to disable monotonic startup mode.
High-Efficiency, 10A, PWM
Internal-Switch Step-Down Regulator
Figure 2. Soft-Start Implementation with External Reference
Figure 3. Typical Application Circuit.
14
______________________________________________________________________________________
POWER-GOOD
2.3V TO 3.6V
R1
OUTPUT
Monotonic Startup Modes (MODE)
V
R2
OPEN
IN
10µF
C24
C1
Undervoltage Lockout (UVLO)
DD
20kΩ
10µF
rises above 2V, UVLO clears and
C2
R2
C
20kΩ
10kΩ
R17
R18
REFIN
10Ω
R1
MAX8566
0.22µF
1µF
C4
C3
R3
50kΩ
23
18
19
20
21
22
24
27
25
28
29
3
1
LSS
IN
IN
IN
IN
IN
V
PWRGD
EN
MODE
REFIN
SYNC
FREQ
DD
DD
DD
is
MAX8566
31
GND
The gate-drive voltage for the high-side, n-channel
switch is generated by a flying-capacitor boost circuit.
The capacitor between BST and LX is charged from the
V
the low-side MOSFET is switched off, the stored voltage
of the capacitor is stacked above LX to provide the
necessary turn-on voltage for the high-side internal
MOSFET.
The switching frequency is resistor programmable from
250kHz to 2.4MHz. Set the switching frequency of the
IC with a resistor from FREQ to GND (R
calculated as:
where f
The MAX8566 features a SYNC function that allows the
switching frequency to be synchronized to any frequen-
cy between 250kHz to 2.4MHz. Drive SYNC with a
SYNCOUT
LSS
PGND
PGND
PGND
PGND
PGND
COMP
BST
LX
LX
LX
LX
LX
LX
LX
LX
SS
FB
High-Side MOSFET Driver Supply (BST)
supply while the low-side MOSFET is on. When
S
4
5
6
7
8
9
10
11
12
17
16
15
14
13
32
2
30
26
is the desired switching frequency in Hz.
0.047µF
C5
SYNC Function (SYNC, SYNCOUT)
R
FREQ
16.9kΩ
R7
C11
0.022µF
2.4kΩ
3300pF
=
0.47µH
0 95
L1
50
.
330pF
22pF
C10
22µF
C9
Frequency Select (FREQ)
k
C6
Ω
µ
s
×
22µF
⎛
⎜
⎝
C7
24.9kΩ
12.4kΩ
f
1
s
−
R5
R6
0 05
.
µ
FREQ
s
⎞
⎟
⎠
1.8V AT 10A
R4
100Ω
C8
120pF
V
OUT
). R
FREQ
is