MAX15035 Datasheet, PDF (10/27 Pages) Maxim Integrated Products – 15A Step-Down Regulator with Internal Switches

15A Step-Down Regulator with Internal Switches
Typical Operating Characteristics (continued)
(MAX15035 Circuit of Figure 1, V_IN = 12V, V_DD = 5V, SKIP = GND, R_TON = 200kΩ, T_A = +25°C, unless otherwise noted.)
DYNAMIC OUTPUT-VOLTAGE TRANSITION
(PWM MODE)
MAX15035 toc28
1.5V
A
1.05V
1.5V
B
1.05V
0
C
-6A
12V
D
0
40µs/div
A. REFIN, 500mV/div
B. V_OUT, 200mV/div
I_OUT = 2A
C. INDUCTOR CURRENT,
10A/div
D. LX, 10V/div
DYNAMIC OUTPUT-VOLTAGE TRANSITION
(SKIP MODE)
MAX15035 toc29
1.5V
1.05V
A
1.5V
B
1.05V
10A
C
0
12V
D
0
40µs/div
A. REFIN, 500mV/div
B. V_OUT, 200mV/div
I_OUT = 2A
C. INDUCTOR CURRENT,
10A/div
D. LX, 10V/div
PIN
1, 17, 27, 31,
39, 40
2
3, 28
4
5, 16
6–15
18–26
29
30
NAME
N.C.
EN
AGND
V_DD
LX
PGND
IN
TON
BST
FUNCTION
Pin Description
No Connection. Not internally connected.
Shutdown Control Input. Connect to V_DD for normal operation. Pull EN low to put the controller into its
2µA (max) shutdown state. The MAX15035 slowly ramps down the target/output voltage to ground
and after the target voltage reaches 0.1V, the controller forces LX into a high-impedance state and
enters the low-power shutdown state. Toggle EN to clear the fault-protection latch.
Analog Ground. Internally connected to EP1.
Supply Voltage Input for the DL Gate Driver. Connect to the system supply voltage (+4.5V to +5.5V).
Bypass V_DD to power ground with a 1µF or greater ceramic capacitor.
Inductor Connection. Internally connected to EP2. Connect LX to the switched side of the inductor as
shown in Figure 1.
Power Ground
Power MOSFET Input Power Source. Internally connected to EP3.
Switching Frequency-Setting Input. An external resistor between the input power source and TON
sets the switching period (t_SW = 1/f_SW) according to the following equation:
( ) t_SW
= C_TON
R_TON
+ 6.5kΩ
⎛ V_FB ⎞
⎝⎜ V_OUT ⎠⎟
where C_TON = 16.26pF and V_FB = V_REFIN under normal operating conditions. If the TON current
drops below 10µA, the MAX15035 shuts down and enters a high-impedance state. TON is high
impedance in shutdown.
Boost Flying Capacitor Connection. Connect to an external 0.1µF capacitor as shown in Figure 1. The
MAX15035 contains an internal boost switch/diode (Figure 2).
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