ISL78235 Datasheet, PDF (1/20 Pages) Intersil Corporation – 5A Automotive Synchronous Buck Regulator

DATASHEET
5A Automotive Synchronous Buck Regulator
ISL78235
The ISL78235 is a highly efficient, monolithic, synchronous
step-down DC/DC converter that can deliver 5A of continuous
output current from a 2.7V to 5.5V input supply. The device uses
peak current mode control architecture to achieve very low duty
cycle operation at high frequency with fast transient response and
excellent loop stability.
The ISL78235 integrates a low ON-resistance P-Channel
(35mΩ, typical) high-side FET and N-Channel (11mΩ, typical)
low-side FET to maximize efficiency and minimize external
component count. The 100% duty cycle operation allows less
than 250mV dropout voltage at 5A output current. The
operating frequency of the Pulse Width Modulator (PWM) is
adjustable from 500kHz to 4MHz. The default switching
frequency of 2MHz is set by connecting the FS pin high.
The ISL78235 can be configured for discontinuous (PFM) or
forced continuous (PWM) operation at light load. Forced
continuous operation reduces noise and RF interference, while
discontinuous mode provides higher efficiency by reducing
switching losses at light loads.
Fault protection is provided by internal hiccup mode current
limiting during short-circuit and overcurrent conditions. The
device also integrates output overvoltage and
over-temperature protections. A power-good monitor indicates
when the output is in regulation. The ISL78235 offers a 1ms
Power-good (PG) timer at power-up.
When in shutdown, the ISL78235 discharges the output
capacitor through an internal 100Ω soft-stop switch. Other
features include internal fixed or adjustable soft-start and
internal/external compensation.
The ISL78235 is available in a 3mmx3mm 16 Ld Thin Quad Flat
No-lead (TQFN) Pb-free package with an exposed pad for
improved thermal performance. The ISL78235 is rated to
operate across the temperature range of -40°C to +105°C.
Features
• 2.7 to 5.5V input voltage range
• 2MHz default switching frequency
• 100ns guaranteed phase minimum on time for wide output
regulation
• Adjustable switching frequency from 500kHz to 4MHz
• External synchronization from 1MHz to 4MHz
• Optional PFM mode for light-load efficiency improvement
• Very low ON-resistance HS/LS switches: 35mΩ/11mΩ
• Internal 1ms or adjustable external soft-start
• Soft-stop output discharge during disable
• OTP, OCP, output OVP, input UVLO protections
• 1% reference accuracy over-temperature
• Up to 95% efficiency
• AEC-Q100 qualified
• Common pinout family allows migration from 3A to 5A
without PCB change:
- ISL78233 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3A
- ISL78234 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4A
- ISL78235 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5A
Applications
• DC/DC POL modules
• μC/µP, FPGA and DSP power
• Video processor/SOC power
• Li-ion battery powered devices
• Automotive infotainment power
Related Literature
• UG015, “ISL7823xEVAL1Z Evaluation Board User Guide”
• ISL78233, ISL78234 Datasheet
L
2.7V TO 5.5V
C_OUT
C_IN
16 15 14 13
VIN ₁
VDD ₂
PG ₃
*ISL78235
PGND
12
PGND
11
SGND
10
SYNC ₄
FB
9
5
6
7
8
V_{OUT 5A LOAD}
DSP, FPGA
*Pin Compatible
ISL78233 - 3A BUCK
ISL78234 - 4A BUCK
100
90
2.5V_OUT
80
3.3V_OUT
1.8V_{OUT 1.5VOUT}
1.2V_OUT
70
60
50
T_A = +25°C
40
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
OUTPUT LOAD (A)
FIGURE 1. TYPICAL APPLICATION: 5A BUCK REGULATOR
FIGURE 2. EFFICIENCY vs LOAD (V_IN = 5V; f_sw = 2MHz; SYNC = GND)
July 1, 2015
1
FN8713.2
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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