MAX1637 Datasheet, PDF (6/20 Pages) Maxim Integrated Products – Miniature, Low-Voltage, Precision Step-Down Controller

Miniature, Low-Voltage,
Precision Step-Down Controller
____________________________________Typical Operating Characteristics (continued)
(V_OUT = 3.3V, T_A = +25°C, unless otherwise noted.)
TIME EXITING SHUTDOWN
(V_OUT = 3.3V, I_LOAD = 7A)
MAX1637-16
OVERVOLTAGE-PROTECTION WAVEFORMS
(V_IN SHORTED TO V_OUT
THROUGH A 0.5Ω RESISTOR)
MAX1637-17
500µs/div
V_OUT
1V/div
V_SHDN
5V/div
10µs/div
V_OUT
100mV/div
5V
V_DL
0V
0A
-5A
INDUCTOR
CURRENT
-10A
______________________________________________________________Pin Description
PIN NAME
FUNCTION
1
CSH
High-Side Current-Sense Input
2
CSL
Low-Side Current-Sense Input
3
FB
Feedback Input. Connect to center of resistor divider.
4
CC
Compensation Pin. Connect a small capacitor to GND to set the integration time constant.
5
REF
1.100V Reference Output. Capable of sourcing 50µA for external loads. Bypass with 0.22µF minimum.
6
SHDN
Shutdown Control Input. Turns off entire IC. When low, reduces supply current below 0.5µA (typ). Drive with
logic input or connect to RC network between GND and V_CC for automatic start-up.
7
SYNC
Oscillator Frequency Select and Synchronization Input. Tie to V_CC for 300kHz operation; tie to GND for
200kHz operation.
8
GND Analog Ground
9
V_CC
Main Analog Supply-Voltage Input to the Chip. V_CC powers the PWM controller, logic, and reference. Input
range is 3.15V to 5.5V. Bypass to GND with a 0.1µF capacitor close to the pin.
Gate-Drive and Boost-Circuit Power Supply. Can be driven from a supply other than V_CC. If the same supply
10
V_GG
is used by both V_CC and V_GG, isolate V_CC from V_GG with a 20Ω resistor. Bypass to PGND with a 4.7µF
capacitor. V_GG current = (Q_G1 + Q_G2) x f, where Q_G is the MOSFET gate charge at V_GS = V_GG.
11
DL
Low-Side Gate-Driver Output
12
PGND Power Ground
13
BST
Boost Capacitor Connection
14
DH
High-Side Gate-Driver Output
15
LX
Inductor Connection
16
SKIP
Low-Noise Mode Control. Forces fixed-frequency PWM operation when high.
6 _______________________________________________________________________________________