MAX5951ETJ+ Maxim Integrated Products, MAX5951ETJ+ Datasheet - Page 11

• Manufacturer Part Number: MAX5951ETJ+
• Description: IC BUCK PWM CTRLR 12V/5V 32-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Step-Down (Buck)r

Specifications of MAX5951ETJ+

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 0.8 ~ 5.5 V
• Current - Output: 10A
• Frequency - Switching: 100kHz ~ 1MHz
• Voltage - Input: 8 ~ 16 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 32-TQFN Exposed Pad
• Power - Output: 2.76W
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX5951 is a PWM, step-down, DC-DC controller.
The device operates over the input-voltage range of 8V
to 16V or 5V ±10% (V
adjustable output from 0.8V to 5.5V. The device deliv-
ers up to 10A of load current with excellent load-and-
line regulation.
The MAX5951 PWM controller utilizes a voltage-mode
control scheme for good noise immunity and offers
external compensation allowing for maximum flexibility
with a wide selection of inductor values and capacitor
types. The device operates at a fixed switching fre-
quency that is programmable from 100kHz to 1MHz
and can be synchronized to an external clock signal
through the SYNC input. The device includes UVLO
and digital soft-start. Protection features include valley-
mode current limit, hiccup-mode output short-circuit
protection, and thermal shutdown.
PIN
EP
24
25
26
27
28
29
30
31
32
NAME
PGND
DREG
REG
CS+
BST
CS-
DH
DL
LX
EP
______________________________________________________________________________________
Detailed Description
IN
Positive Current-Sense Input. Connect CS+ to the synchronous MOSFET source (connected to
PGND).
Negative Current-Sense Input. Connect CS- to the synchronous MOSFET drain (connected to LX).
Power-Ground Connection. Connect the input filter capacitor’s negative terminal, the source of the
synchronous MOSFET, and the output filter capacitor’s return to PGND. Connect externally to AGND
at a single point near the input capacitor return terminal.
Low-Side Gate-Driver Output. DL is the gate-driver output for the synchronous MOSFET.
Gate-Drive Supply for the Low-Side MOSFET Driver. Connect externally to REG and the anode of the
boost diode.
Source Connection of the High-Side MOSFET and Drain Connection of the Synchronous MOSFET.
Connect the inductor and the negative side of the boost capacitor to LX.
High-Side Gate-Driver Output. DH drives the gate of the high-side MOSFET.
High-Side Gate-Driver Supply. Connect BST to the cathode of the boost diode and to the positive
terminal of the boost capacitor.
5V Regulator Output. Bypass with a 2.2µF ceramic capacitor to AGND.
Exposed Pad. Connect the exposed pad to AGND.
= V
REG
12V/5V Input Buck PWM Controller
) and provides an
V
typ) before any PWM operation can commence. The
UVLO circuitry keeps the MOSFET drivers, oscillator,
and all the internal circuitry shut down to reduce cur-
rent consumption.
Override the internal PWM UVLO divider by connecting
an external resistive divider from IN to PUVLO to AGND.
The PUVLO threshold is 1.220V with 122mV hysteresis.
The MAX5951 soft-start feature allows the load voltage
to ramp up in a controlled manner, eliminating output
voltage overshoot. Soft-start begins after V
the UVLO threshold. The soft-start circuitry gradually
ramps up the reference voltage. This controls the rate
of rise of the output voltage and reduces input surge
currents during startup. The soft-start duration is 1024
clock cycles. The output voltage is incremented
through 128 equal steps. The output reaches regulation
when soft-start is completed, regardless of output
capacitance and load.
IN
must exceed the default PWM UVLO threshold (7V
FUNCTION
Pin Description (continued)
PWM Controller
Digital Soft-Start
PWM UVLO
IN
exceeds
11