OneTech Integration · DC/DC Converters · Quarter Brick

COQ Series

Name: COQ Series Quarter Brick DC/DC Converter
Brand: OneTech Integration
Availability: InStock

175W / 50A isolated quarter brick DC/DC converter with Sink-Plate technology. Patented Buck Reset topology achieves 145 W/in³ at greater than 91% peak efficiency — the highest power density available in a standard quarter brick open-frame package.

Quarter Brick >91% Efficiency 2:1 Input Range Sink-Plate Options OCP · OVP · OTP RoHS · CE · UL 4.41M hrs MTBF

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175W

Max Output Power

145

W/in³ Power Density

>91%

Peak Efficiency

COQ Series Quarter Brick DC/DC Converter

Why COQ Series

Maximum Power,
Minimum Footprint

The COQ Series pushes quarter brick performance to 175W / 50A with 145 W/in³ power density — nearly 20% higher than comparable quarter bricks. Sink-Plate base-plate options enable direct chassis conduction cooling for demanding thermal environments.

145 W/in³ Power Density

Patented Buck Reset topology combined with synchronous rectification achieves the highest power density available in a standard quarter brick open-frame package — enabling higher power in the same PCB footprint.

Sink-Plate Technology

Four base-plate options (1.0mm Metal, 3.0mm Metal, 3.0mm Sink-Plate, 5.0mm Sink-Plate) allow direct conduction cooling to the chassis wall or cold plate — eliminating external heatsinks in thermally constrained enclosures.

SR + Buck Reset Dual Optimization

Synchronous rectification eliminates output diode loss. Buck Reset topology minimizes switching loss. Combined, these two innovations deliver >91% efficiency — directly reducing thermal dissipation at the system level.

Full Protection Suite

OCP (108–125%), OVP (115–130%), and OTP (110°C Tc) operate simultaneously. PC pin supports positive and negative remote on/off logic for clean multi-rail power sequencing.

Industry-Standard Quarter Brick

Same footprint and pin assignment as the CBQ Series. Drop-in upgrade path for existing quarter brick designs — same PCB, higher current, more power without layout changes.

4.41M Hours MTBF

Bellcore TR-332 Issue 6 verified at GB/25°C. Multi-layer single-sided PCB minimizes solder joint count and thermal hot spots — directly addressing the two leading causes of DC/DC field failures.

Package Options

Choose Your Base-Plate

Open Frame — Metal

1.0mm Metal Plate

29 g

Open Frame — Metal

3.0mm Metal Plate

43 g

Sink-Plate

3.0mm Sink-Plate

Conduction cooling

Sink-Plate

5.0mm Sink-Plate

Enhanced conduction

Complete Model List

Available Configurations

All models share the same quarter brick footprint. Specify base-plate code (d) to select package type. Contact OneTech Integration for custom voltages or current ratings beyond the standard range.

Part Number	Input Range	Max Input	Output Voltage	Output Current	Max Output	Efficiency
COQ48120abcd-14XXX	36–75V	184W	12.0V	14A	168W	91%
COQ48070abcd-21XXX	36–75V	163W	7.0V	21A	147W	90%
COQ48050abcd-35XXX	36–75V	195W	5.0V	35A	175W	90%
COQ48033abcd-35XXX	36–75V	131W	3.3V	35A	116W	89%
COQ48025abcd-50XXX	36–75V	146W	2.5V	50A	125W	86%
COQ48018abcd-50XXX	36–75V	106W	1.8V	50A	90W	86%
COQ48015abcd-50XXX	36–75V	90W	1.5V	50A	75W	84%

Part Number	Input Range	Max Input	Output Voltage	Output Current	Max Output	Efficiency
COQ24120abcd-12XXX	18–36V	160W	12.0V	12A	144W	91%
COQ24050abcd-30XXX	18–36V	168W	5.0V	30A	150W	90%
COQ24033abcd-35XXX	18–36V	131W	3.3V	35A	116W	89%
COQ24025abcd-40XXX	18–36V	146W	2.5V	40A	100W	86%
COQ24018abcd-50XXX	18–36V	106W	1.8V	50A	90W	86%
COQ24015abcd-50XXX	18–36V	90W	1.5V	50A	75W	84%

* Contact OneTech Integration for special input/output configurations or custom current ratings.

Electrical Specifications

Complete Technical Parameters

All specifications typical at nominal input, full load, 25°C unless otherwise noted.

Input

48V Operating Range	+36V to +75V DC
24V Operating Range	+18V to +36V DC
48V Transient (100ms)	100V Maximum
24V Transient (100ms)	50V Maximum
48V Power-ON Threshold	+34.0V to +36.0V
24V Power-ON Threshold	+17.0V to +18.0V
48V Power-OFF Threshold	+31.2V to +33.2V
24V Power-OFF Threshold	+15.6V to +16.6V
Off-State Input Current	6 mA Max (at Vnom)
Latch-State Input Current	8 mA Max (at Vnom)
Reflected Ripple Current	30 mA rms / 100 mA p-p (Lext=10µH)
Input Cap. 48V Models	10.0 µF Max
Input Cap. 24V Models	22.0 µF Max
Ripple Rejection (<1kHz)	−50 dB (Vnom, Full Load)

Remote Control

Logic High (Enable)	+3.0V to +6.5V
Logic Low (Disable)	0V to +1.0V
PC Pin Voltage Range	−0.5V to +12V DC
PC Pin Input Current	−0.5 mA to +1.5 mA

Isolation Voltage

Input to Output	2.0 kV Minimum
Input to Case	1.0 kV Minimum
Output to Case	0.5 kV Minimum

Output

Voltage Accuracy	±1.0% typical
Line Regulation	±0.2% (full input range)
Load Regulation	±0.2% (0% to 100% load)
Temperature Drift	±0.03%/°C (−40°C to 100°C)
Output Tolerance Band	±4% (all conditions)
Ripple & Noise (20 MHz)	3% p-p / 1% RMS of Vo
Over-Voltage Protection	115–130% Vo
Over-Current Limit	108–125% Io (at Vnom)
Voltage Trim Range	±10% Vo (Vnom, 10% load)
Step Load (2.5 A/µS)	±6% Vo / 500 µS
Start-Up Delay	20 ms / 250 ms (Vnom, full load)

General

Switching Frequency	330 kHz typical
MTBF (Bellcore TR-332 #6)	4.41 × 10⁶ hrs @ GB/25°C
OTP Trip Point	110°C (Tc) ±5°C
Operating Temperature	−40°C to +110°C
Storage Temperature	−55°C to +125°C

Weight by Package

1.0mm Metal Plate (code M)	29 g
3.0mm Metal Plate (code S)	43 g
3.0mm Sink-Plate (code A)	Contact factory
5.0mm Sink-Plate (code B)	Contact factory

⚠ Absolute Maximum Ratings — Do Not Exceed

Input voltage: −0.5V to +40V DC (24V models) / −0.5V to +80V DC (48V models). Remote Control: −0.5V to +12V DC. Exceeding limits may permanently damage the device and void warranty. Always protect input with a fuse.

Physical & Mechanical

Package & Pin Definitions

Industry-standard quarter brick pin assignment — identical to CBQ Series. Golden over Nickel plated copper alloy or brass pins. M3×0.5 stainless steel mounting inserts (4 places).

Input Side

−IN

Negative Input

Remote On/Off Control

+IN

Positive Input

COQ Series

Quarter Brick · Open Frame

2.30" × 1.45" (58.42 × 36.83 mm)
Base plate: Aluminum alloy with anode oxide

Output Side

+Vo

Positive Output

Positive Remote Sense

TRIM

Output Voltage Trim ±10%

−S

Negative Remote Sense

−Vo

Negative Output

Pin Length Options (b-code)

0.12" / 3.05mm

0.16" / 4.06mm

0.20" / 5.08mm

0.24" / 6.10mm

TOLERANCESStandard dimensional tolerances apply to all package dimensions unless otherwise specified.

Notation .xx (2 decimal)	±0.02 in (±0.5 mm)
Notation .xxx (3 decimal)	±0.01 in (±0.25 mm)
Unit system	Inches (millimeters)
Base plate	Aluminum alloy with anode oxide
Mounting inserts	M3 × 0.5 stainless steel (4 plcs)
Max torque	3.9 in‑lb (0.44 Nm)
Pin material	Copper alloy or Brass
Pin plating	Golden over Nickel

Weight

29g / 43g

1.0mm / 3.0mm metal plate

Footprint

2.300" × 1.450"

(58.42 × 36.83 mm)

Open Frame Package — Mechanical Drawing

All dimensions in inches (millimeters) · Tolerances: .xx ±0.02 in (±0.5mm) · .xxx ±0.01 in (±0.25mm)

Performance Data

Efficiency, Waveforms &
Thermal Derating

All measurements at nominal input and 25°C unless noted. The COQ48033 achieves 92.07% peak at 48V/17.5A — exceptionally flat from 10A through 35A.

Typical Waveforms — COQ48033abcd-35XXX (V_IN: 50V, Load: 35A)

Start-Up Waveform

V_IN: 50V · Load: 35A

Ch1: Output VoltageCh1 High: 1.26V

Transient Response

V_IN: 48V · Load: 18A → 9A @ 2.5A/μS

Recovery within 500 μS±6% Vo

Input / Output Ripple

V_IN: 50V · Load: 35A · L_IN=10μH

Output p-p: 162mVRMS: 8.007mV

COQ48033abcd-35XXX — Efficiency vs. Load Current (A)

36V input

48V input (nominal)

75V input

Thermal Derating Curves — Load (A) vs Ambient Temperature (Tc = 110°C)

COQ48033abcd-35XXX — 400/300/200/100/20 LFM

Max 35A @ 48V input

COQ48120abcd-14XXX — 400/300/200/100/20 LFM

Max 14A @ 48V input

Thermal Summary — COQ48033 (Open Frame)

20 LFMFull 35A to ~60°C ambient

100 LFMFull 35A to ~80°C ambient

200 LFMFull 35A to ~90°C ambient

400 LFMFull 35A to ~100°C ambient

OTP TriggerTc = 110°C ±5°C

Key Waveform Parameters

Start-Up Delay20 ms (Vnom, full load)

Step Load Recovery±6% Vo / 500 µS

Output Ripple p-p3% Vo max

Output Ripple RMS1% Vo max

Switching Frequency330 kHz typical

Target Markets

Where COQ Series Works Best

The COQ's 50A output capability, 145 W/in³ density, and Sink-Plate options make it ideal for high-current point-of-load applications where space, efficiency, and thermal management all matter.

📡

Telecom Base Stations

48V bus in BTS, RRU, C-RAN. 50A output drives high-current ASICs and FPGAs directly from the 48V bus.

🖥️

Servers & ASIC Power

50A capability for high-current processor rails. Sink-Plate enables conduction cooling in sealed chassis.

🔌

Networking Equipment

High-density switching platforms. Multiple COQ modules in parallel deliver scalable current.

🏭

Industrial & Defense

−40°C cold-start, Sink-Plate for chassis-mounted conduction cooling in sealed or unpressurized enclosures.

Part Number Builder

Configure Your Part Number

Build a valid COQ part number. Note: Base-Plate code (d) selects the package type and determines Sink-Plate vs metal plate.

Series

Input Voltage Bus

Output Voltage

Enable Logic (a)

Pin Dimension (b)

Standoff Height (c)

Base-Plate / Package (d)

Output Current Rating

Generated Part Number

COQ48120P00M-14XXXX

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COQ Series

Maximum Power,Minimum Footprint

Choose Your Base-Plate

Available Configurations

Complete Technical Parameters

Package & Pin Definitions

Efficiency, Waveforms &Thermal Derating

Where COQ Series Works Best

Ready to Specify the COQ Series?

Maximum Power,
Minimum Footprint

Efficiency, Waveforms &
Thermal Derating